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Unsubstantiated Mass Hysteria Targets Trifexis

I don’t know what it is about the psyche of certain people. They yearn to choose conspiracy over the obvious, somehow garner security from their own distrust of everyone and live their lives looking for the next professional expert to expose as incompetent, unscrupulous and in league against them. In the face of difficult circumstances, these same people often feel the need to blame someone or something for their misfortune, that somehow pinpointing and targeting the reason for their problems, makes tough situations more easily accepted.

Atlanta-based consumer investigative reporter Jim Strickland was contacted by a so-called “victim” of the flea, heartworm and parasite preventive Trifexis, and was pointed to a Facebook page called “Trifexis Kills Dog.” The alleged canine victim had died within two days of taking the product according to its owner. It did not matter that dog was 12 years old, was under treatment for a serious endocrine disease called Cushings Disease and that Elanco (the animal division of Ely Lilly, the pharmaceutical that manufactures the product) paid to have a post mortem examination that found heart failure to be the cause of death, with no link to Trifexis. Heart failure is, however, linked to Cushings Disease, the aforementioned endocrine disorder this dog was under treatment for.

Nonetheless, this reporter saw an angle and remained undeterred, playing on the emotions of the type of people that are ripe for such news, regardless of lack of objective evidence to substantiate the story. The story came to my attention initially because a colleague of mine was quoted out of context for the report and follow-up article on the Trifexis story. My veterinary colleague, who has some experience in dealing with media, forgot the golden rule of talking to reporters, and that is to never answer them with one thought broken up in separate sentences.   Here is how it went down.

The reporter asked my colleague in light of the negative publicity of Trifexis, if he has ever seen reactions after administration of Trifexis to a dog. My colleague answered, “I sometimes see reactions. Reactions are not very common and it has never been anything beyond minor GI upset.”  The reporter printed, “I sometimes see reactions.”

The truth about Trifexis is that it is a very safe product for use in the prevention of heartworm disease, fleas and the three of the most common types of intestinal worm parasites in dogs. Where fleas and heartworm disease are serious year-round issues, such as here in Florida and other southeast states, Trifexis has been a life sustaining preventive product for some patients. 

I have been carrying Trifexis for the past two years, during which time I have sold thousands of doses for hundreds of canine patients. It is very popular for its all-in-one preventive approach, but in Florida where there is flea resistance to long-standing veterinary grade topical flea preventives; it has been especially successful in controlling flea outbreaks.  I have not seen one single serious reaction to Trifexis, just the occasional canine patient (about 1 in 40-50) whose gastrointestinal system cannot tolerate the product and experienced vomiting or diarrhea.  It is otherwise a good product for the vast majority of dogs who take it.

This situation is dismaying to me, not because I have pity for the multibillion dollar pharmaceutical company that makes Trifexis, but because it is yet another example of sensational, unethical reporting to a certain segment of people all too eager to buy it hook, line and sinker.  Some of the posts on the article, as well as the Facebook page, are difficult for veterinarians to stomach, with people accusing us of peddling this product, knowingly intoxicating countless dogs, thinking more about our revenue stream from the product than for our patients. One person wrote, “…I don’t know if I can ever trust another veterinarian ever again.”

To set the record straight, veterinarians recommend products like Trifexis because they safely prevent disease. While we earn a profit for the sale or medications, supplements, immunizations and medical services, the vast majority of us make our recommendations based on the well-being of the patient’s we treat. I would strongly discourage denying your dog the disease preventive benefits of a product like Trifexis on the basis of unethical reporting and certain types of people who choose to believe it over the judgment of their veterinarian.

Dr. Roger Welton is the President of Maybeck Animal Hospital and CEO/Chief Editor of the veterinary information and blog online community, Web-DVM.

112 thoughts on “Unsubstantiated Mass Hysteria Targets Trifexis

  1. T. Williams, Ph.D. says:

    I am a biologist and did a some internet research following an incident with my dog following Trifexis administration. A common thread in some of the complaints by dog owners seems to be excessive drinking, extreme lethargy, abdominal bloating, and old age of the dog often with the complication of Cushing’s disease. This is exactly what I observed in my dog, a 15 year old corgi newly diagnosed with Cushing’s. Given the involvement of the adrenal glands and impaired ability to respond appropriately to stressors associated with the disease is it possible that older dogs with this condition would have a more difficult time with processing Trifexis? Admittedly, this is likely to be a very small population of dogs and my other younger dogs have never had a problem with this product. But given the timing and resolution of the symptoms and well as the similarity in cases it would be worth further research and perhaps some guarded caution with the elder dog community.

    • Dr. Roger says:

      Dr. Williams,

      Thank you for your thoughtful commentary. No direct link has currently been established between age, adrenal disease, and and increase in complication; certainly not death. However, one cannot discount your observations, especially if your observations are substantiated across a wider spectrum of geriatric and/or cushinoid cases than we or Elanco (the company that manufactures Trifexis) is aware of. I certainly warrants a closer look at there statistically being a correlation. I plan to explore this further with my the Elanco veterinary practice liaison. Again, I thank you for the constructive and reasonably stated input.

      Best regards,

      Dr. Roger

      • Alexei says:

        this product also just killed our 6 month old puppy. It caused him to go into anaphylaxis and into shock.

        This company has no idea how to write warning labels and it doesn’t want to because there are many more side effects except for “occasional vomiting after intake”.

        i am sorry that you are so apologetic and dismissive of information coming from many owners who lost their dog but its true. The only vet that has told me that this stuff is horrible and should be pulled is the one who is NOT vested, did not sign a gag agreement and is not the one pushing it to pet owners. Let that sink in.

        my vet didn’t even tell me about necropsy as an option when i asked if i can have more details of result of death (even though we already knew it but i needed proof).

        so what is it? “mass-hysteria”? or paid articles by Elanco?

        • Alexei says:

          go to ER animal clinic and talk to ER vets that actually see the effects of Triflexis and not the people who sell them and simply don’t care.

          yea any medication can have adverse effects so why dont you put on the label and INFORM the pet owner BEFORE they make a call, thinking you have their interest at heart, to use this poison.

          it literally like chemo.

  2. Greetings Dr. Welton:

    I only recently became aware of your article about my November story on Trifexis. I would very much appreciate hearing your feedback directly if you would be so kind as to call.

    I am a bit puzzled by your blog post, as I can find no quotation “I sometimes see reactions.” in any of my material. I’d love to know whom you believe I interviewed to have heard that quotation. Maybe I’m missing it in my notes.

    I know I didn’t print it. I work in television and write electronically for our website. I don’t print anything.

    • Dr. Roger says:

      Mr. Strickland,

      I will have to contact my colleague who was interviewed to re-confirm…it has been a while. I will my due diligence and get back to you ASAP. If I was mistaken, then I will make the correction…I take my own blogging seriously and I do not wish to wrongfully accuse anyone of stating some he did not. I will post here as soon as I confirm or refute this claim. However, this one comment notwithstanding, I remain undeterred in the main premise of my post, that your reporting of this so called deadly connection to Trifexis despite all of the evidence to the contrary. The FDA data clearly shows that its safety matches statistically with other heartworm preventives in its class. From a clinical standpoint, having offered it as an option for my own patients for now three years, I have not observed this so called deadly connection.

      I am so confident in the safety of the product, that I have my own 8 year old Yellow Lab on it.

      I will return shortly once I connect with my colleague.


      Roger Welton, DVM

      • Alexei says:

        killed my dog on Friday. third usage, allergic reaction and shock and following death. 6 month old healthy puppy.

    • Jessica says:

      Good Day Jim Strickland,

      This product just killed our dog.
      Please feel free to contact me.

  3. Claire says:

    It’s not mass hysteria, this killed my dog and many others. I am absolutely certain it killed my Peaches, and I started the so called “mass hysteria”. Yes I am the founder of the Facebook page and the petition, and you have personally offended me. It’s a good thing I believe in karma. After all, what goes around will one day come back around.

    • Dr. Roger says:


      I am truly sorry for the loss of your dog, but the data and clinical evidence does not support you notion that Trfexis is deadly. Aside from an occasional case of diarrhea or vomiting, Trifexis has proven itself to not only be an effective product, but a safe one for the past three years that we have carried it. If you took the time to look at the FDA data on Trifexis, you would clearly see that the safety statistics are in line the other preventives in its class. All Trifexis is, is a combination of two active ingredients, each of which have been around a long time. The heartworm preventive in Trifexis is milbemycin oxime, the same active ingredient in older generation heartworm preventives Sentinel and Interceptor. The flea preventive in Trifexis is spinosad, the same active ingredient in Comfortis, an oral flea preventive that predates Trifexis by three years. If Trifexis is so deadly, then why do we not see the same claims about Sentinel, Comfortis, and Interceptor?

      On the other hand, with no seasonal kill offs, fleas and mosquitoes are a year round problem here. Flea directly irritate the dog’s skin, spread disease, cause infections, and pose a health risk to people, especially small children and the elderly. Mosquitoes spread deadly heartworm disease. Thus, when I see people being scared away from a product that can help maximize quality of life and prevent serious, even deadly disease, through nothing more than sensationalism and assumptions that all of the data refutes; it is troubling. Do you know that there is a member of your Facebook page who had a 12 year old Schnauzer that died after being on Trifexis for four years? It does not matter that at 12 years of age, within the average life expectancy of a Schnauzer that any number of things cause illness and death. It does not matter that the dog did fine on Trifexis for 4 years. The bottom line is that the dog died while on Trifexis, so that must be the cause of death.

      This manufactured Trifexis controversy reminds me of the Swiffer controversy that erupted in 2007. A woman had a 12 year old German Shepherd – a very old dog by that breed standard – who took ill and died of liver failure a few days after she used a Swiffer in her home. Although her veterinarians never insinuated the connection, this person hit the internet with reckless abandon, shouting from the roof tops that the Swiffer killed her dog. It did not matter that her dog was 12 years old, beyond the life expectancy of a German Shepherd, and that the most common causes for liver failure in a patient this age are inflammatory, infectious, or cancer. It did not matter that the ingredients in the Swiffer were no different that common household cleaners that have been around for decades and not linked to liver failure in dogs. This person was convinced the at the Swiffer killed her dog, and she ran with it to the point that I began to get questions about it from clients of my clinic.

      In the case of the Swiffer, I really did not care much; given that there was no negative consequence to my patients if people avoided the Swiffer, even if avoided for no good reason. However, in the case of the a preventive that is an integral modality to protect dogs and their human families, I take issue with unsubstantiated claims of its danger, as well as reporters all too willing to stoke the emotions of devastated owners seeking a reason for the loss of their pet.

      I will leave you with this – my own 8 year old yellow Labrador Retriever, Bernie, is maintained on Trifexis. Bernie is a vital member of my family and means the world to us. I would never knowingly put him in harm’s way. If I saw any data that substantiated the notion that Trifexis is deadly; or saw evidence of this in clinical practice, not only would I cease and desist its use and sale for my patients, I would most certainly not keep my own dog on it. Upon examination of FDA data, not one single post mortem examination of a dog supposedly killed by Trifexis confirming any connection to Trifexis and cause of death, that evidence simply is not there.

      You made mention of your wish to have Karma come back around at me…I am not sure what you are referring to. If advocating for my patients as a biochemist and practicing veterinarian – with the unique understanding of pharmacology, physiology and medicine that provides me – is creating Karma I may face in the future, I welcome it.

      Thanks for taking the time to comment. Again, I am sorry for your loss.

      Best regards,

      Roger Welton, DVM

      • Jewels Berg says:

        I just stumbled across this and thought I would share with you some information. After the story regarding Trifexis originally aired, many of us in the Industry went to the Gallo’s page and tried commenting. We were cursed, threatened and called murderers. So I started the Facebook Group called Trifexis Does Not Kill Dogs. Shortly after I recieved a message in private from Claire apologizing for the way we were treated. She claimed they did not know if Trifexis even killed their dog. She states it was started as a memorial and that her grief stricken Father took over the site and turned it into the Trifexis Kills Dogs. Originally when he takes over if you go back and look all his posts are encouraging people to band together and start a class action lawsuit. I have screen shots of these messages and what her intentions were and what her Father had done to the site. So in light of the messages I have from Claire they have been copied and saved. I also have more information regarding this reporters source that I would share in an email but not in a comment. I just felt after reading the comment Claire left she is very confused and has changed her story several times. It is sad how many people this story has frightened and I have proof that they had other intentions.

        • Claire says:

          Oh shut up, you piece of shit. It is true that I am not positive, but I am pretty sure. You completely twisted what I said to your own advantage. I am positive that you work for Elanco and you don’t give a flying fuck about people’s beloved pets. I hope you get yours one day.

          • Claire says:

            It is true that my father twisted the page for my dog into something different that I didn’t want, and that is what I was trying to explain to you. He was saying crazy things to people and I never wanted that. I just wanted to warn pet owners and create a memorial to my dog. My dad ruined everything and I agree with you on that, but I think you misunderstood what I said. I am sorry about my previous message, I let my emotions get the best of me. It’s been 6 years, let’s move on.

      • Sarah Caffery says:

        I enjoyed reading both of these comments. Why has no one mentioned the Neurological Side Effects that Trifexis causes? Bc it does cause those things and several Trifexis advocates told me that “Neurological side effects” are listed on the label.

        Let me put it this way: If you give your dog Trifexis and 3-5 hours later he has lethargy or neurological side effects that lead to seizures which lead to further damage resulting in death, then yes, Trifexis is the cause. If you give it to your dog and two weeks later something happens, it is probably NOT trifexis.

        Don’t knock those of use who don’t lie to news reporters. Don’t knock those of us who administered the drug and found negative reactions in our dogs within the next 12 hour window.

        • Dr. Roger says:

          I would agree there is a direct correlation, as there is no other explanation. I have seen exactly what you are describing in one patient and when I called Elanco about it, they conceded that this is a rare but documented side effect. Thus, while not common, your observations have been documented. You are wise to avoid Trifexis.

      • Dr. I have looked at the FDA data, and it would seem to me that the majority of testing only occurred over a 30 day period.
        My dog has been taking Trifexis for over a year, and within the initial year she had slight reactions, mostly being bloated and gassy, and slightly lethargic.

        Well, this has now changed, the last 2 doses have left her with violent diarrhea, and on the last treatment which was given Friday, she is now also vomiting green bile 3 days after the dosage administration.

        The first time that this happened, I did not attribute it directly to the Trifexis, but at this point in time, there is no doubt in my mind that this is the cause of her maladies, as this is a recurring pattern.

        Your insistence that this is a safe product may be somewhat unwarranted, and perhaps the FDA needs to go back to the drawing board and see what the long term effects of this drug are doing to the livers of the dogs that are taking this.

        • Dr. Roger says:

          I have been clear that Trifexis occasionally does not agree with the GI causing vomiting and/or diarrhea. From my experience, this occurs in about 1 in 50 patients, roughly the same many other preventives on the market. For these patients, like for your dog, I would not use Trifexis or any preventive that does not agree with an individual’s GI system. If you are concerned about long term side effects of Trifexis specifically, then you should logically have the same concerns about long time favorites, Sentinel or Interceptor…their HW preventive active ingredient is Milbemycin Oxime, the same as Trifexis. I would logically also avoid the popular monthly oral flea preventive, Comfortis, as its active ingredient is spinosad, the same active flea preventive ingredient in Trifexis. All Trifexis is, is a combination of the active ingredients of popular older flea preventives that no one has written scathing written about or posted frightening stories about…yet. Hope your dog is well, and good luck!

        • RUTH NELSON says:

          Trifexis is a killer and the conmpany know it. I lost my collie to it and maimed another. The company were rude and vulger in their manner when I complained.

      • Gary Shaw says:

        Dear Dr. Welton, I’ve read your posts and your responses and appreciate your medical and personal opinions. You come across with intelligence and calmness and make a lot of sense. I think all of us think “Oh my God, I’m consciously giving my dog mass toxic poison! How could that be good for him?” But now I get it. It is good for them and spares them from high risk resulting in pain & suffering. Thank you again for your well presented thoughts and researched presentation. Seems there’s always mass hysteria when an animal dies unexpectedly. It’s very difficult as we love them dearly like our children and try our best to protect and save them from harms way. Trefexis is with doubt a very strong medicine but then again we immunize our very own children to protect them from fatal diseases and that somehow is ok. Again, thank you for sharing your professional thoughts.

    • yeney says:

      Im with you…because of Trifexis my beautiful Mia cocker spaniel is currently in the hospital with severe pancreatitis very very sick 🙁 I hope she comes out of these I would due anything so that they stop prescribing Trifexis

    • J. Kutche says:

      Claire, Our Chihuahua was given Trifexis when he was 3 years old. A very loving, well behaved, potty trained lovable dog. FIrst does he got all upset and vomiting. Vet said I did not feed him enough food before giving trifexis to try it again the following Month. I fed him half a can of wet dog feed same thing only this time he could not get off floor on his own. Never gave it to him again. He had immediately after second does, Skin problems, Severe sore spots, anger issues, could not always tell who we were and often attacked and asked questions later.. I complained to my VET his response was.. “My Sales Person says that is all hype.” I said really your sales person.. I call BULLSHIT its all the kick back and BULLSHIT that left mny dog in a living hell.. He could still play and be a good dog at times.. Others he seemed like he knew he was not the same.. Now at 6 years old I have to put him down. I am convinced all his issues are due to Trifexis.. And someone needs to stop this shit… I say ssue the hell out of Trifexis and vets blindly listening to their SALES MEN.. lol


      Bye Tucker RIP on 5-12-1965 10 am That is tomorrow by the way Trifexis..

  4. Sarah Caffery says:

    I am surprised that this blog was posted to Web-DVM. I thought they held higher standards for writing blogs but the opening statement of “I don’t know what it is about the psyche of certain people. They yearn to choose conspiracy over the obvious…” is heart breaking. What makes this Vet better then Jim Stricklands bogus article? There is nothing wrong with my psyche and i didn’t choose conspiracy; I saw the reaction. The title, opening, and other statements that basically call me crazy for seeing the neurological side effects Trifexis had on my dog is offensive. This article is an insult to those of us that don’t lie to news reporters about our pets.

    Why can’t someone write a good article without calling either side, who is for or against trifexis, stupid? My dog does NOT have Cushings or any other condition and he had to be rushed to the hospital (Trifexis told us to take him immediately) because he was having neurological side effects. My swift actions saved my dog and he is still with me today. I would be happy to send an email with the video footage of my pet.

    Why can’t people realize that recalls can and will happen with lots of medications. Yes, recalls do happen! How many people drove toyota cars before they had their big break recall a few years ago? It takes quite a few complaints to prove that something is not safe. I think a lot of us that DO see the dangers in Trifexis are just worried that it will get to that point, however, I know that hundreds and thousands of more dogs will need to have adverse reactions/deaths before it is recalled. Has anyone given thought to this?

    Why do people feel the need to defend Trifexis and try to tell us that it 100% didn’t cause adverse reactions when we saw it with our own eyes? Recalls can happen, it is a safety thing. Cigarettes were considered safe at one point but not anymore and now they have age requirements and such. do you see what I am saying??

    • Dr. Roger says:

      Ms. Caffery,

      Perhaps my use of words were not the best choice; but I have seen time and again not only with Trifexis, but with other circumstances where owners distraught with emotion at the loss of a pet, will always seek someone or something to blame, no matter how unscientific or even against common sense reason. I was had a lady bring her 14 year old cat to me, seeking a third opinion that her cat had lymphoma. I advised an ultrasound, a diagnostic that had not yet been done by any previous veterinarian, yet one that may give her the definitive answers she was seeking. With pancreatic, gut, spleen and liver lesions sen on ultrasound all being supportive of a diagnosis of lymphoma, I gave her the likely diagnosis. I made a treatment recommendation that she declined while she took time to think about it, and in the process, her cat died a week later. She came to my office enraged that I killed her cat, convinced that the ultrasound is what killed her (despite the fact that the cat was 14 and was sick with lymphoma, the treatment for which she declined; and despite the fact that ultrasound is so safe it is used routinely on pregnant women). This lady went to the Florida State Veterinary Board to submit a grievance, went to a law firm to file a suit, and wrote the Better Business Bureau. When she failed to succeed in getting any of the above to take action, she even went to a local news station consumer reports whistle blower reporter to “expose” me. She failed there as well; lucky for me, she did not come across Mr. Strictland. This is the kind of “psyche” I am referring to in my article, the ilk of which is all too prevalent in the Trifexis controversy.

      If my wording was less than eloquent, I recognize that and I thank you for pointing out that I may have chosen my words better. I am not one to make excuses, but my choice of words may have been influenced by my own frustration with the sensationalism I have witnessed with all of this. In the case of your dog, you are seeing a direct correlation between administration of the preventive and a subsequent neurological presentation. On the FDA label for Trifexis (and its sister flea preventive Comfortis), it is clearly contraindicated for any dog suspected to have any level of seizure disorder, as it has been occasionally documented to lower the seizure threshold and precipitate seizures in these patients. Thus, for patients with known seizure disorders, we flag their account that they are not to ever be treated with Trifexis or Comfortis. This is likely the case with your dog, and you are being wise, proactive, and advocating for your dog by choosing not to use Trifexis. There is nothing sensational about that.

      Where I get frustrated is in cases where pet owners have been affected by the sensationalists and draw a sharp line at using a product because of it. Here is Florida, where fleas are a year round nuisance and even serious health hazard, refusing to treat otherwise healthy dogs with Trifexis because this media frenzy has scared people, is not only troubling, but hampering our ability to optimally maintain the health of our patients.

      That is not to say that Trifexis is for every patient, nor is any medication for that matter. There are occasional patients whose GI systems cannot tolerate the drug, and thus vomit or get diarrhea from it. Others have documented neurological issues that it is not worth risking medicating with Trifexis, so we avoid it in these cases, no differently than we avoid certain vaccines or antibiotics that particular patients proved to be allergic to.

      ANY drug has a list of side effects that have been documented, no matter how rare or uncommon. Just looking up the possible side effects of Advil (that includes sudden death from acute liver failure) can be terrifying. However, in the greater context, these side effects have to be listed because they have occurred, but we hardly expect them to happen as they are so rare.

      If my article offended you, you have my sincere apologies. Please know that based on your posts, you are most certainly not the type of pet owner that I was eluding to. In hind site, my choice of words could have carried more sensitivity, but I stand by the general content of the article. Because of our year round flea issues in Florida, as a Florida practitioner, I have a much higher number of patients on Trifexis than veterinarians in other areas of the country. Thus for 3 years, I have a great deal of experience with the product, and have had few issues with it. For a handful of cases that cannot tolerate it GI-wise, for patients with known neurological disease, and for dogs like yours that show neurological signs post administration, I simply advise choosing another product. But the people convinced that it kills dogs and that veterinarians are complicit in this knowledge and ignore it to protect our financial bottom lines, those sentiments are both untrue and unfair.

      Thank you for taking the time to post.

      Best regards,

      Roger Welton, DVM

      • J. Kutche says:

        Youa re full of it… We knew what was happening to Tucker long before I knew others were having issues with Trifexis.. You are a abomination to your profession.. Take a pill called Groacet and maybe you will see the truth and stop living behind the pay offs..

        • Robert shoemaker says:

          I love how people always seek to blame somebody for there issues…. whoever think that a person goes to vet school to make money really needs to re-examine there thinking. When was the last time you looked at a vets salary! They make shit, bottom line. And no they don’t get money from the big “pharmaceutical companies”. People go through vet school knowing they will be in debt for life most likely, it’s not about the money. We go through school because our love and compassion for animals. As dr roger has stated if you show me SCIENTIFIC proof of trifexs and these so called related deaths not only will I take my pets off of it but stand with you. It’s still gets me how people think they know everything! Unless you went to school to not only specialize in animal medicine but pharmacology, then please don’t state facts that have no scientific facts. I’m deeply sorry for your loss, I do understand what it’s like, but for god sake look at at the medical facts. Also as dr roger has explained no matter what medication we’re talking about there will be side effects. Just like medication effects is differently it will be the same for animals.

    • ruth newsome says:

      Thank you I could not have said it better.

  5. June says:

    My dog was put on Trifexis by my vet when Interceptor was not available. My vet was well aware of my dog having pre-existing epilepsy. When I got home, I read the label and immediately called her and she assured me that it was safe to give to my boy. I told her I was concerned with the warning label but since I am not a vet, I gave my dog the pill. When I first gave it to him, he immediately spit it out. I wrap it around some wet food but had to force it down his throat. Within an hour he started acting strange. He became lethargic, started stretching his neck towards the ceiling and would not respond to me. Soon the diarrhea started. The next day he would not eat AT ALL, which is very unusual for him. I called the vet, she said just to watch him and since it was a Saturday to call if he was not better by Monday. I called again on Sunday and they prescribed an anti-diarrhea med. On Monday, he still would not eat so I took him in. My vet would not admit that it could be the Trifexis and suggested that I split the dosage in half. She could not explain his neck stretching behavior or why he would not eat. I decided that day to fire her, find a new vet and a new heartworm med. What irritates me is that it seems as if vets are not knowledgeable on the effects of this drug. All they want to do is to defend it even though many pet owners have experienced similar of not worse reactions to this drug. I put my trust in my vet (by the way, this way a huge animal hospital AAHA National Award finalist) and it is very discouraging that no one listened to my concerns. I feel that most of the veterinary community is turning a blind eye to it’s patients and putting all their trust in a multi-million dollar drug company.

    • Dr. Roger says:

      Ms. Weeten,

      In this case, your veterinarian recommended a product whose primary contraindication for use is for patients with a known history of neurological disease. For any new patient about to go on Trifexis, my technicians are all trained to ask if there is any history of seizures or other known neurological disease. Our Elanco representative puts on what are called “lunch and learn” sessions where she sets up a lunch time seminar for the doctors and medical team of my hospital. From the launch of the product, through each session she has put on for introduction to new products and updates on Trifexis and other lines of products Elanco has, she has warned time and again of this neurological contraindication of the product. This warning is also clearly listed in the product’s label.

      Thus, in your case, if everything you have written is accurate, it appears that this veterinarian, and/or hospital as a whole, were not paying attention to information that is constantly offered to our industry, both directly from the manufacturer, on the product label, and through routine continuing education. If that is truly the circumstance, that is very disappointing for me to hear. I will tell you that your experience is the exception to the standards of our industry. The last thing a veterinarian wants is for a patient to become ill or die because of our decisions, most commonly due to a higher sense of duty to our patients and their families, or at the very least, to avoid a stain on our record. Thus, “turning a blind eye” is not something I would expect any veterinarian would do.

      Thank you for taking the time to share your story. I hope all works out well for your dog.

      Best regards,

      Roger Welton, DVM

      • J. Kutche says:

        If anyone gives their pet Trifexis they are giving a live in hell penalty.. Stop giving this large dose pesticide to your vets.. These So called VETS are full of shit .

      • Kathryn says:

        I would like to preface this by explaining, I am not a “hysterical” person and desire to base my decisions on sound logic, reason, and scientific evidence. I say this to clarify before I am automatically thrown into the mob mentality and mass hysteria you speak of. My question is in regard to the potential danger of the combination of the two active ingredients. You continue to repeat as evidence of the safety of Trifexis, the historical and, current safe and successful use of medications with one of the two ingredients found in Trifexis. As a healthcare professional myself, working with the human population as opposed to animals I truly and simply have no axe to grind but merely, a desire for more information regarding this subject in general.
        I haven’t researched the ‘studies’ and scientific background of the medication, as I am just now becoming aware of this topic specifically, but was curious about potential contraindications and adverse effects of the medication that I was never informed of by my vet.
        I understand fully that causation cannot be determined in many of these cases where there are a multitude of variables that cannot be controlled as they would ideally be in a clinical/ research trial, but my curiosity is in regard to research conducted before and after this medication was brought to market. As someone who identifies as an active pro-vaccination individual who seeks to end these episodes of mass hysteria that potentially cause more harm than good, especially when the people who tend to start such wild fires have no formal education, training, and/or experience with which to be speaking about, let alone propagating such dangerous incendiary ideologies such as that of “anti-vaxxers”. That being said, I hope you understand that my intention is not to approach this topic with emotion and pseudo-science. I am not opposing what you are saying but merely would like more information, as I respect you and your expertise in the profession and study of veterinary medicine. I am not familiar with the FDA guidelines and processes involved with veterinary medicine and am humble enough to admit although I may be privy to human healthcare processes I am less so with veterinary and animal healthcare processes, which is why I would just like more information on the topic. I understand your anger at people jumping to conclusions and hope you are able to look at my inquiry objectively and not take a defensive tone.
        I look forward to hearing from you.

  6. June says:

    Thank you Dr. Welton for your response. Yes, everything I said was exactly the truth and I have it documented. This happened nearly 3 years ago when the drug first came out. It is my understanding that Elanco has made amendments to the label adding more warnings. I called Elanco and reported my dog’s reactions to the drug and they gave me a full refund on Trifexis. I am still quite upset with my previous vets reaction to my concerns. I really liked her and had put all my trust in her. Maybe since it was a new drug, she was not familiar with the effects of the drug; I don’t know but when I questioned what I read on the warning label about the pre-existing epilepsy, she said in a condescending tone that “only 1 dog in the testing had a seizure so they had to put that on the warning label, not to worry” I just wonder if Trifexis will be one of those drugs that eventually gets recalled but not after many pets are adversely affected.

    • Dr. Roger says:

      Ms. Weeten,

      I do not think it will be recalled any time soon, nor should it based on 3 years of data that does not justify such a move.

      However, it is incumbent upon every veterinarian to be well aware of it contraindications, as well as recognize legitimate side effects when they are reported by owners, EVEN uncommon ones.

  7. Jerri says:

    I must respectfully disagree with the concept that this is mass hysteria. In January we gave our heathy dog Trifexis, it was in the evening. When we went to bed a couple hours later he started pacing and panting. He would jump on and of the bed all night long. When daylight came, he calmed down only for it to reoccur nightly. We to our dog to the vet. She did many, many tests and found nothing physically wrong with him. We began lavender oil massages at bedtime and he has been on melatonin. That has reduced his anxiety attaks to about once or twice a night. It is October so we have been dealing with this for 10 months. To me, a healthy dog given a medicine only to go through such a change with a few hours of the dose, the medicine was directly responsible. I did not know there was an issue with Trifexis when I made the assumption that our dog had a reaction to the med. it seemed way too cut and dry. Please understand those of us posting on facebook are loving pet owners who have personally seen the effects of this drug.

    • Dr. Roger says:

      May I ask a few questions prior to replying to you? 1.) How old is your dog? 2.) Had he been on Trifexis before, and if so, for how long? 3.) What do the “anxiety attacks” look like? THanks for taking the time to engage in this discussion.

      Best regards,

      Roger Welton

  8. William Clements says:

    It is interesting that the comments seem to ignore the thousands of reports of middle aged dogs who have succumb to lymphoma and other types of cancer within relatively short time of taking this product. I realize that sites like these rely on the advertising dollars of these veterinary pharmaceutical companies however one cannot just keep saying that these folks are buying into mass hysteria. There are literally thousands of posting about dogs developing illnesses as the result of this drug. Coincidentally, or maybe not, I have never seen a drug pushed so hard by so many vets in my life.

  9. Joseph Hinkle MD says:

    Do you believe that simply because you have not observed fatal or life-threatening adverse events temporally associated with this med after prescribing it for ‘hundreds’ of pets in your practice that you can rule out a safety concern when used in tens of thousands or hundreds of thousands of pets? I don’t think so.

  10. Tracey Trosclair says:

    Yet I know two people who had major complications. 9 year old Weimaraner died and a Schit Tzu had seizures after a dose, switching to trifexus.. I asked them both after they told their stories if they had been on Trifexis. They both answered yes. I don’t need the internet to persuade me. I listen to the people I know personally. 1 person knowing two people in her town. Interesting odds.

  11. Roxan says:

    You must be making a great deal from Elanco to stand up to these statements and oppose pet owners chalking up their pets death to “mass hysteria”. Shame on you. What foolish comments you have made. I pity any animal that has you as their vet because first of all you are missing the scientific facts behind these cases and you are seriously lacking compassion.
    What would you do if you didn’t have a big drug company as your supplier? Hmm… Save lives?

    • Dr. Roger says:

      You clearly have never worked in a veterinary clinic, as you opine from a position of innuendo and assumption this refelcts no real understanding of how the veterinary industry works. The truth is that the mark up on preventives is very poor when we have to compete with online pet medication giants that get massive bulk buy discounts from the same pharmaceuticals that convince us to carry their products. I write far more prescriptions for Trifexis and other preventives than I sell from my own pharmacy, as the in-house supply of preventives that we carry continues to decrease as the online purchasing trend continues to rise. It is predicted among industry experts that within 5 years time, the veterinary in-house pharmacy will all but disappear, now that companies like Walmart and Target are getting in on the pet medication game…so even those who choose to not purchase online have a more cost effective option that veterinarians cannot compete with.

      Thus, veterinary hospitals have more of a “necessary evil” kind of relationship with veterinary pharmaceuticals than any kind of financial partnership as you erroneously insinuate in your post. Preventive sales only represent 2% of yearly gross revenue of my practice, of which Trifexis represents less than 0.5%. Although Trifexis was initially very popular because of its strong ability to kill fleas and prevent heartworm and intestinal parasites, two major problems here in Florida, its one drawback is that it does not taste very good, making it challenging for some dog owners to administer. There is a new once every three month oral flea/tick preventive made by Merck that is as effective and tastes good, so a lot of dog owners are opting instead for that in combination with monthly Heartgard to protect against heartworm and internal parasites. Since my Labrador retriever eats anything and everything, I continue to give him Trifexis, not because Elanco pays me to, but because Bernie is a beloved family member who I wish to keep healthy and free of fleas and heartworm. I also have small children I do not want exposed to fleas and intestinal parasites, so there is my added incentive to use a product that I know to be safe and effective for our family dog.

      Of course, regardless of what I state, you are probably thinking at this moment that Elanco is writing me a check for posting these sentiments. I do not know why I waste my time responding to posts like this, but I just can’t help myself. I offer Trifexis as an option to my patients simply because it works, and aside from a couple of contraindications, it is no more potentially harmful statistically than any other preventive on the market. The science is clear on this after 3 years of FDA trials pre-product launch and through monitoring after 3 plus years being on the market. When someone makes a statement after getting the results of a post-mortem examination showing no link to Trifexis being the cause of death like this: “I know the autopsy did not prove it, but I know in my heart Trifexis killed my dog”; (an actual statement from a person who came forward with a claim that Trifexis killed her dog), that is not science. In fact, after countless post mortem examinations (called necropsy in veterinary medicine, not autopsy, FYI), not one single one has been reported to confirm a link to death by Trifexis.

      I also get my children vaccinated, acknowledge that global warming is real, and accept evolution. Why? Because the science supports these assertions. Science and medicine drive my decisions for my patients, they should for any responsible medical practitioner.

  12. April says:

    Good Morning, Dr. Roger,

    Thank you for writing this article with a fairly objective perspective. I get especially irritated with the number of people sparking mass hysteria with unsubstantiated proof for the next latest “conspiracy”, as well. I just wish people would step back from their emotions in order to make a much more objective assertion. Emotions most certainly can blind our judgment, even when our intentions are good. We have to remember, though, that it goes both ways. Sometimes, our pride in certain things (say science or tradition, for example) can also blind us to facts. A case in point would be your views on evolution. Scientists declare that the closest relative to the homo sapien is the chimpanzee, which has a neo cortex three times smaller than a human. The neo cortex is responsible for logic and reasoning, which is surprisingly viewed as “coincidence”. The ape-like ancestor that the homo sapien and the chimp are descended from is non-existent, as well as the thousands of other transitional species that it would take to evolve from this “ancestor” to a human being. Every mutation would also have to add new information (mutations result in a loss of information) and evolution would have to be pretty, rather than messy and violent (not every mutation would work and therefore, we would have a large amount of fossils with deformities and/or combinations that did not sustain life).

    Anyway, I digress, as your article was about the mass hysteria targeting trifexis. I can understand the cases with some of the people above whom have indeed had legitimate issues with trifexis, as nothing is 100%; however, the cases with the older dogs who were already dying is preposterous. Those are cases where these people were clearly blinded by emotions. I’m hoping that we can all get to a point where we can take a deep breath, step back from our emotions, and look at evidence rather than the next conspiracy. Objectivity is certainly paramount, as slander affects us not just on a personal basis, but also corporately and globally. Thank you again for your information, and given that I am also in Florida, I may have to take my dog in to see you (depending on which city you are located in, of course), as he seems to be losing small patches of fur on his back and face. He is on Trifexis, but had those patches prior to dosing.

    Peace and blessings,


  13. Lisa Chestnutt says:

    Our normally healthy dog, Ace. Died of liver cancer. Ace was switched to Triflexis several years ago at the advice of our vet. Ace did have a tick borne illness, but that is not what killed him.
    After being placed on Triflexis I noticed increased thirst, lethargic behavior,loss of appetite, black tar like stools and the most strange symptom of all…eating dirt…and I mean obsessively eating dirt..digging insanely, when he never had before.

    Last year he was suspected of having ehrilichiosis. We kept Ace on Triflexis against my wishes. I finally switched him a few months ago.

    Ace was very sick a few weeks ago, and I really thought we should just have him put to sleep. We opted to have him operated on thinking perhaps a spleen tumor existed. His entire liver was eaten up with cancer.

    No one, and I mean no one will ever convince me Triflexis did not do this. I have training in animals science and a background in biology.

    I read the studies on Triflexis and the MSDS sheets on Triflexis and Comfortis. Warnings like : liver damage, kidney damage, and bone marrow damage are there. Animal organs are very much like people organs.

    Triflexis was only tested in 176 dogs for 180 days. Many of the symptoms we saw early on in Ace did exist in the dogs who were tested. Irregardless of Triflexis’ positive effects, I’ll always believe it killed my dog. I can’t bring him back, but I can fight to inform other dog owners. Elanco is in the money making business plain and simple. Triflexis is the most expensive treatment on the market…and in my opinion it is the most deadly too!

    I think my dog would be alive today, had he been given different medications for fleas and ticks. In the past, I’d used Hartguard, and Interceptor. I wish I’d stuck with Hartguard, Frontline and any other flea treatment. I’ll always blame myself for allowing Triflexis to be prescribed for my dog. I’ll fight until it is taken off of the market to tell others not to use it on their dogs.

  14. Lynn says:

    It is time for my dogs dose of trifexis. Someone told me about this concern over the weekend so I Googled the issue. I found many posts with people claiming the drug either killed or caused issues for their dogs but not one veterinary with the same concern. (Unless I missed it). I have noticed in the past that my dog seems a little sluggish for a day or so after taking the pill. but never sick. I did find when researching that it should be given with food. based on this research I’m going to give my dog her dose with food and trust that she would feel much worse if infected with fleas or heartworms.

    • J. Kutche says:

      Don’t do it if you love your dog… It is not worth the complications. Get Interceptor it is back on the market..

  15. I am stunned that you have dismissed the numerous reported illnesses and deaths of dogs given this product as unsubstantiated mass hysteria. While there is no direct ’cause’ yet determined by the manufacturer of Trifexis or veterinarians, simply because none have been undertaken, the numerous reports of illness and death reported by dog owners is certainly sufficient “correlation” to warrant further studies of the drug to determine what is causing a significant percentage of dogs to fall ill and die from its use.

    My veterinarian prescribed Trifexis for my dog. When I was told it had a “horrible smell,” so bad that I should unwrap it outside and leave it for a day prior to trying to “conceal” it in especially flavorful doggie-food so as to fool my dog into eating it and then if, quite likely I was told, she vomits it up, not to worry—just try again, and again, until she finally ingests it, I had some doubts about it. The unopened box sat on my counter for almost a month, where I would eye it uneasily. I finally decide to “google” the product to see what I learned. I learned a lot. Enough to return it to my vet, who refunded my hundred dollars but likewise stated, like you, that the internet information was unsubstantiated hysteria and even went further trying to explain it. I didn’t buy it then and I don’t buy it now.

    No dog owner would knowingly risk the well-being or life of her dog by using this product when there are many other products on the market known to be safe (enough). If nothing else, veterinarians should disclose this information, that there have been reported cases of illness and death as result of using Trifexis, and let dog owners decide whether they wish to find out if there dog may be one of the ‘casualties.’

    I don’t know what the incentive is for you and other vets to continue supporting this drug in light of all the reported deaths. I still like and trust (relatively) my veterinarian, but something stinks here, and it’s not just Trifexis.

    • Dr. Roger says:

      Indeed, any reports of averse effects warrant further study of any product, and that was exactly what has occurred, including numerous post-mortem examinations on reported cases, as well as a 3 year FDA retrospective review, which determined the safety of Trifexis to be in line with all of the other preventives on the market. Not having a taste appealing to a dog is hardly grounds for concluding that a product is toxic…most dogs don’t particularly like brussel sprouts, but I would not draw the conclusion that they are toxic because of that fact.

      If you actually smell Trifexis, it has an earthy smell to it, which contributes to its less than stellar palatability….largely because the active flea killing ingredient, spinosad, is derived from soil dwelling bacteria that naturally produce this substance that has powerful insecticide properties. Did you know that since it is naturally occurring molecule, if a commercial farm that has label claims of being organic uses spinosad as an insecticide, it may still legally be called “organic”? But don’t take my word for it, see yourself the wonderful uses of the “organic insecticide” at Mother Earth News:

      At any rate, spinosad was first introduced not as Trifexis, but as an oral flea killing agent for dogs about 3 years prior to Trifexis coming out, in a product called Comfortis. I am just wondering where all the reports of cases of toxic death from Comfortis are, since it has the same flea killing agent as Trifexis. Oh, I know, it must be the heartworm preventive agent in Trifexis, milbemycin oxime. But that does not seem to make sense either, because that is the same active ingredient in the long established heartworm preventive products Sentinel and Interceptor. Those products have been around so long that they predate my veterinary school graduation year (2002); yet in all that time there is no media frenzy over their danger.

      I will tell you why there are no no reports of immense danger of these other aforementioned products that separately have the same active ingredients in them as Trifexis…no one has yet made a Facebook page announcing that they kill dogs, nor have they gotten the attention of an unscrupulous journalist that runs with the story. I find it comical when people come into my office and have bought the Trifexis is toxic story, determined to avoid it like the plague, but then ask me for Interceptor and Comfortis for heartworm and flea control, respectively…and I have to break it to them that Trifexis is actually Interceptor and Comfortis combined in one product. But hey, if you would prefer to pay double for 2 separate products that collectively have the same active ingredients as Trifexis, that is your prerogative if it helps you sleep better at night.

      Since veterinarians increasingly are writing prescriptions for preventives, there really is no incentive to rebut sensational tales of the so called danger of Trifexis, other than wishing to facilitate our clients in making decisions for their pets’ care based conclusions derived from real science and common sense, as opposed to emotion, innuendo, and conspiracy theory (and unethical journalism).

      I will leave you with this: the first reported case of death by Trifexis was a dog that was over 12 years old, and was under treatment for congestive heart failure and Cushings Disease. He had been on Trifexis for 2 plus years prior to his death. Cause of death determined by an independent post mortem examination was complications from congestive heart failure. You seem like an intelligent person, so please just put your common sense hat on for one moment. The dog was under treatment for congestive heart failure, as well as an endocrine disease known to both cause congestive heart failure and aggravate existing congestive heart failure…patient died of complications from congestive heart failure, proven by post mortem examination and pathology. Dog was already on Trifexis for 2 plus years with no previous problems.

      If you were the owner of this dog, would you have still concluded that Trifexis killed your dog, then made a Facebook page about it and went on TV talk about it? Because that is exactly what the owner of this dog did, which was ground zero for the controversy…and now here we are still talking about it.

      Best regards,

      Dr. Roger

      • Kathryn H. says:

        I would like to preface this by explaining, I am not a “hysterical” person and desire to base my decisions on sound logic, reason, and scientific evidence. I say this to clarify before I am automatically thrown into the mob mentality and mass hysteria you speak of. My question is in regard to the potential danger of the combination of the two active ingredients. You continue to repeat as evidence of the safety of Trifexis, the historical and, current safe and successful use of medications with one of the two ingredients found in Trifexis. As a healthcare professional myself, working with the human population as opposed to animals I truly and simply have no axe to grind but merely, a desire for more information regarding this subject in general.
        I haven’t researched the ‘studies’ and scientific background of the medication, as I am just now becoming aware of this topic specifically, but was curious about potential contraindications and adverse effects of the medication that I was never informed of by my vet.
        I understand fully that causation cannot be determined in many of these cases where there are a multitude of variables that cannot be controlled as they would ideally be in a clinical/ research trial, but my curiosity is in regard to research conducted before and after this medication was brought to market. As someone who identifies as an active pro-vaccination individual who seeks to end these episodes of mass hysteria that potentially cause more harm than good, especially when the people who tend to start such wild fires have no formal education, training, and/or experience with which to be speaking about, let alone propagating such dangerous incendiary ideologies such as that of “anti-vaxxers”. That being said, I hope you understand that my intention is not to approach this topic with emotion and pseudo-science. I am not opposing what you are saying but merely would like more information, as I respect you and your expertise in the profession and study of veterinary medicine. I am not familiar with the FDA guidelines and processes involved with veterinary medicine and am humble enough to admit although I may be privy to human healthcare processes I am less so with veterinary and animal healthcare processes, which is why I would just like more information on the topic. I understand your anger at people jumping to conclusions and hope you are able to look at my inquiry objectively and not take a defensive tone.
        I look forward to hearing from you.

  16. SSantos says:

    I’ve been doing a ton of online research regarding Trifexis side effects. I have read tge arguments for and against. I’ve been to the Facebook page referenced here and read the horror stories. Here’s my story:

    Ace is 6 months old. We started him on Trifexis on February 25th. He vomited the morning after. Reading that vomiting is a common side effect, I didn’t panic, but kept a close eye on him. He seemed fine after that.

    We gave Ace is second dose on March 25th. Five days later he vomited (I keep a detailed calendar noting anything that happens with Ace). After that bout of vomiting, he seemed fine.

    Ace got his third dose on April 25th. Again, 5 days later, he vomited. After the one bout of vomiting, he seemed fine. I’m noticing a pattern here.

    This past Monday, May 25th Ave was given his 4th dose of Trifexis. Yesterday, he began vomiting after every meal. He is not keeping anything down and he is lethargic, sleeping a lot. He is definitely not his usual self and he began licking his right paw non-stop. His paw is soaking wet from the non stop licking and it’s red. His throw up has started coming up a bright yellow color. I tried giving him plain rice and boiled chicken last night. He ate everything, but it all came back up.

    Given the pattern, I am inclined to believe it’s the Trifexis. He has been perfectly healthy. Now, I am extremely concerned.

    • Dr. Roger says:

      I would have recommended ceasing treatment with Trifexis after the second vomiting episode, as it clearly does not agree with your dog. One time could be an isolated incident, twice to me is a pattern.

      Hope he is well.



  17. Mike says:

    The fact your ignoring the rest of the planet and the deaths of dogs after taking this drug astounds me. There are websites dedicated to spreading awareness from all over the world. In australia the dogs are getting sick and dying and they are reporting the deaths as “heart related deaths” the same as the USA, admitting they have no idea what caused it. You have to be pretty dense not to understand logic and see that if a dog gets sick and dies right after taking a brand new drug then it has to be the drug that caused the death. Shame on you. I thought you were scientific in thinking.

    • Dr. Roger says:


      I am scientific, which is why I follow statistical data, not Facebook pages and forum threads…I also observe effects on the 3500 dogs that frequent my clinic.

      The data and my vast experience does not support your assertions.


      Dr. Roger

    • Whitney says:

      Like your comment, Mike. The author of this blog post continually sites using scientific data to come to his conclusion that Trifexis is safe. What about HUMAN DATA? HUMAN EXPERIENCE? Tens of thousands of people are just jumping on the so-called “mass hysteria” bandwagon? To accuse as such is highly insulting. Because most of us aren’t vets or scientists, or our EXPERIENCE isn’t valid or proof enough that Trifexis CAN and often (too often for my blood) DOES cause harm? This Dr is extremely offensive in tone, and condescending in opinion.

  18. Sassy's Mom says:

    I live in a suburb just north of Atlanta and have a soon to be 10 year old female mini schnauzer that has been on Trifexis for 5 years. She gets it mixed in with her regular dry food once a month to ensure that she doesn’t have it on an empty stomach and she has never experienced any adverse reactions…not even an upset stomach.

    When I saw Jim Strickland’s series of stories about Trifexis causing the deaths of several local dogs, I took them with a grain of salt, realizing that as with all medications there are contraindications. As far as I know, no medication is universally tolerated by all patients.

    I love my dog dearly and would be absolutely heartbroken if something were to happen to her. However, I just do not understand the “the throw the baby out with the bath water” attitude of some of these dog owners (calls for class-action lawsuits, product recall demands, petitioning vets to remove Trifexis from their shelves, detox recipes on Facebook…) Trifexis works well for a lot of dogs, including mine. The sad reality is that our pets will eventually leave us and sometimes there’s no one or nothing to blame.

    Side note: A few years ago, the vet gave my dog the 7 in 1 vaccine, even though I requested the 5 in 1 because I was concerned about potential effects of the Lepto portion. When we got home, she went under a table and was unresponsive. The vet wanted me to bring her back immediately to start IV fluids because she was having a serious reaction to the Lepto vaccine.(Potentially fatal? She wouldn’t say.)

    I couldn’t return right then because it was lunch and nap time for my 20 month old grandson. Recalling that Benadryl might counteract the effects of the vaccine I asked the vet if she would tell me how much to give my dog until I could bring her in; after about 10 minutes of heated persistence on my part, the vet acquiesced and gave me the dosage. (By now, the baby’s crying and my dog is drooling). I gave her the Benadryl and by the time my grandson woke up from his nap, she was returning to her old self and there was no need to return to the vet.

    Needless to say, we have a new veterinarian and I now INSIST that my dog not receive the 7 in 1. It is definitely contraindicated in her case. No petitions, no recall demands, no detox potions; just no Lepto for her.

    As for Trifexis, I do not know if my dog will continue to tolerate it as she ages. She gets blood work done before her annual teeth cleanings and so far she’s healthy as a horse! But should that change and if she develops health problems that contraindicate the administration of Trifexis, we’ll find an alternative.

    My intent is to share my dog’s experience with Trifexis and to share how a “routine” vet visit had an unintended outcome. My intent is not to belittle or minimize the grief of those who have lost beloved pets.

  19. Diane says:

    A lot of lengthy info here, I will be brief. My 8 year old Aussie doodle (70 pounds) in perfect health, or so we thought, because he alwYs saw the vet and was in great health, just passed. Could it be the “heart” that is often a diagnosis after a dog dies? I don’t know and will not spend the money to find out. I’d rather just get him cremated and spread hos ashes in our backyard in Florida. Just last Saturday he was playing like a puppy with his stuffed animals. Such a wonderful dog, almost human like. Then I gave him the Trifexis. He didn’t want to take it, used a lot of peanut butter to get it down, and in 36 hours he died, just like that. He just layed down and died. I remember telling my partner that we wouldn’t ever give it to him again since he really hated it so much. After being on it for a year, he just died… I am warning my friends and thinking, “what if I had listened to my gut feelings at that time and never given it to him”. Would he be alive today? My heart is broken

    • Whitney says:

      Diane … this is HEARTBREAKING. I’m so sorry. My Penny had been on it for over a year of her 1 year-7 month life. She had a seizure after each of her last 2 doses. Obv stopping it, but I’m so worried she’s going to have residual effects months or years from now.

  20. Leighpea says:

    I am really surprised that anyone would call this “unsubstantiated” at this point. My vet reported the neurological side effects to the manufacturer after a perfectly healthy young rat terrier I was fostering experienced just a few hours after ingesting Trifexis. Like some others have commented, he would stretch his neck like he was looking up but he had his eyes closed. He shivered and shook for several hours, couldn’t walk. Fortunately he slept it off and was fine the next morning but it certainly gave us a scare. There are other, much more safe alternatives to flea and tick prevention that I would use in a heartbeat over this or similar ingested products. It’s not worth the risk of long term damage or death.

  21. Gworl says:

    “A healthy young rat terrier I was fostering” that is the statement correct? Considering you were fostering, you have no idea the dogs health background, correct? I would imagine the answer is that you did not know the dogs medical history. With that being the case there is no way of knowing if there was a pre-existing neurological disorder. If so, then yes it is possible for the drug to create or aggravate this disorder. The doctor has been very clear of this. We have three blood related boxers. Two males and a female. The males have done great on Trifexis for the span of their lives so far. The female could no take it due to upsetting her stomach. She was removed from the drug. The males are still on it. My big male of 120 pounds, does feel a little bad for the first day. He will sleep most of the day. But haven’t had any other reaction to it. This leads me to the question for the doctor. Should I continue to giving him the medication or switch him to something else? I live in the middle eastern part of Tennessee. I also use the Soresto (spelling) collar. This is a serious question and not a bait for debate. I just want to make sure he is using the right combination of things to protect him from all possible parasites.

  22. Cindy says:

    My cat developed hemangiosarcoma of the spleen & had a splenectomy due to bursting of the tumor 6 months after his first dose of Comfortis. It is 3 months later & he died this past Saturday. It had metastasized to his liver. The people who make this stuff & market it as safe are monsters. I will never get the sounds of his pitiful cries while he died those final hours out of my head.

  23. Izzy says:

    Both my dogs have been on Trifexis for the past 3 years. When it’s time to take their monthly dose, they both refuse to take it. I crush it and mix it with peanut butter. One dog seems to tolerate the medicine, but the other shows symptoms of vomiting, restlessness at night, and apathy during the day. I took her to the vet diagnosed her with pancreatitis. He prescribed antibiotics and something else I don’t remember…
    Here are my questions:
    Since the dogs refuse to take the medicine, is it a sign that it is bad for them? Are they capable to sense that there is something wrong with it?
    Is pancreatitis a side effect of Trifexis? Could some side effects appear after taking the drug over a long period of time instead of within the next days after ingesting it?

    • helloworld says:

      Listen up people. From 2013 to May, 2014 I lost 2 dogs on trifexis. My MIL lost 2 and it was only till recently that we put two and two together.

      My healthy 17yr old sheltie mix within a few months of switching from Revolution to Trifexis died. My 4lb 2 yr old Chihuahua died from HGE which if your not aware is deadly in this breed and a common problem. My MIL lost a 5 lb terrier mix after a 3 month dose pack. She was 11 and died shortly after receiving a dose. She also lost a 15 lb mini pin who began to have seizures. She was 15, so she was euthanized. At 14 lbs, I first started noticing my 17 yr old sheltie mix with upset stomach on first dose about 2-3 hrs after. Another two months goes by and he starts showing seizure like activity. One more month and he shows liver failure and dies. This was a dog who was vibrant, healthy and felt like he was 10.

      But all of my stories relate back to me and my vet. I pay my vet to keep me informed on recalls. But honestly as a pet owner, do u take the tiny print insert and read the scientific jargon or just give them and trust ur vet to do. I dont keep up on recalls either. I read about side affects and I started them on meds. So to me, I wasn’t informed enough by lack of research on my part about side affects, I could have wrote them down or the manufacturer could make print large enough to read and concentrate more on short term and long term side affects/interactions rather than the chemical chain. I dont plan on making it or think it will help figure out whats going on with med.

      I believe that that heartworm medication blood levels should be taken to determine if this drug has a build up in system capabilty. This may be reason behind slow deaths. If “no footprint” in bloodwork either, then I need to do research.

      One thing I havent read or heard regarding Trifexis is that Part of the medication is made in china. After china pet snack recall i got rid of snacks but didnt kno about this.

      And one other thing I have not seen mentioned is what if its just the fact that its too much of a dose and more potent than thought? Im upset with myself, my vet and this company. If we have to buy through vet, the
      Manufacturer needs to give a clear understanding on where to find recalls. I know most companies have a sign up program just have never done any. I relied to heavily on my vet who relied to heavily on the manufacturer who failed to report problems to vet as well as a way to have vets report. Everyone has to do their part.

  24. Dr. Roger says:

    In case anyone is interested, I posted an update on this “controversy” in my 2015 year end wrap up post:

  25. Dr. Roger says:

    Happy New Year to all! 🙂

    Dr. Roger

  26. Kelley Hilla says:

    There aren’t as many cases with Comfortis documented, because the company won’t acknowledge them. The devastating side effects were not known. I believe Spinosad is the culprit in both drugs. I say this because I went through the euthanization of one dog and three day ICU hospitalization of the other.

    I worked as a tech/receptionist for several years at high end clinics. I trusted my vet who trusted the reps who said what they were paid to say. I understand this is a giant money maker, and the fear of lawsuits if it eventually is pulled.

    Comfortis was the only newly introduced product in our home. I missed the petit mal seizures due to it being such a highly recommended product. After a dose our dogs would “see ghosts” (neurological). Then my 75 pound lab mix had a grand mal seizure and aggressively attacked my husband when the dog came out of seizure. No health issues previous. My 5 pound chihuahua mix was found not breathing and unresponsive after next dose. We almost lost her as well.

    The company had the nerve to tell us it was off label use as the chi can fluctuate between 4.5 to 5 pounds. They also stated there is an “acceptable loss rate” with any new drug.

    Pea has not had further seizures or complications since being taken off Comfortis. It is hard to pinpoint when a company refuses to acknowledge issues. Most people may not think to request bloodwork to compare to previous bloodwork. Interestingly, liver values skyrocket along with neurological issues popping up in most cases.

    Are there some pets that had underlying issues? Sure! Mine did not, and many others have been young, healthy animals. Instead of dismissing cases as “unsubstantiated mass hysteria”, more needs to be researched about the many cases. Instead of treating grieving owners as lunatics, maybe we should be interviewed by third party without money or reputations to lose. Of course the media is going to sensationalize coverage. That gets ratings.

    I don’t care about ratings. I care about the health of pets.

  27. Anne says:

    When people try to pull out their “scientific proof” rationale it makes me laugh. The tobacco people do it. The NFL brain injury people do it. And now I see this vet do it in defense of Trifexis and Comfortis. It seems that some people try to use this defense to put themselves on a pedestal to look down upon people who haven’t taken a statistics class. Anyone, including me who has taken a multitude of statistics classes and conducted research studies and written papers discussing the results KNOWS that EVERY research study ever done starts with a question. Yes, many times in the beginning when bad things start happening: first case, second case, third case and on, it is viewed as anecdotal, coincidental, and “Oh it couldn’t be that.” Researchers ask questions! The fact that this Rx appears to be causing illness and death raises questions that should be researched NOT ridiculed. The fact that people have suffered the loss of their family members, then to be “poo-pood” by “authority figures” into thinking that it couldn’t have been the Rx is horrendous, uncaring, shortsighted and ignorant. Also, the fact that statistics are being used to cause harm to the well-being of caring people smacks of questionable ethics. At minimum it’s not giving all the information that would allow people to fully understand the aspects of a research study and getting to say, “There is conclusive (at the .05 level of significance) scientific evidence.” These tragic stories should be rendering an immediate interest and determination to further the studies rather than having someone stand on a pedestal and hold on to being right while there are animals dying. There are times in life when anecdotal evidence is ALL that’s available and every consumer must educate themselves. Practicing an open, inquisitive, logical and reasonable approach will serve anyone well. All I know is based on my empirically derived study with a mere sample size of ONE, my dog Bella who has been taking Comfortis since last Summer will be removed from it after two consecutive bouts with pancreatitis one month apart starting 7-10 after taking the pill. I’m extremely angry at myself for not researching the Comfortis-pancreatitis connection after the first bout. That’s what moved me to put this reply on this site. Sure she’s been on it for over 6 months, but as anyone knows medication can build up in the body and cause harm without symptoms until a time that it does. (Think: cancer grows without causing pain, until it does and many times is too late) Also, the fact that I saw a study on Comfortis only took place for 90 days causes me to question the longitudinal effects of these medications. Am I going to keep giving the Rx to Bella while we wait for the manufacturer to 1) acknowledge that there is a potentially litigious liability if they admit there is a problem; 2) set up and pay for further studies; 3) be willing to forego the millions of dollars being made? That could take years, or may never materialize. I am my dogs advocate just as I am my own when it comes to our healthcare. Therefore, the Comfortis STOPS NOW. Any reasonable person would conclude the same.

    • Dr. Roger says:


      What kind of dog is Bella?

      Dr. Roger

    • Brandi says:

      Anne!! I am SO with you!. Guess what? Dr’s don’t know everything. Not only am I a patient, a diabetic patient, who went to 4 Dr’s who diagnosed me with various things until I ended up at the ER. I also call on Dr’s for my job. Dr’s/Vets do NOT know everything. I appreciate this Vet sharing his opinion based on his client population, but what matters is that this drug Trifexis has NOT been tested long term. end of story. I agree with another post above who mentioned that cancer thrives on damaged cells. Trifexis and others are systemic poison. I refuse to give anything like this to my Aussie. She is 1.5 years old and I am in the NW where heart worm is rare fortunately, so instead i will take her in for blood tests yearly. BTW for Dr. Roger, my dogs vet also refuses to give systemic trifexis to dogs, especially Aussies! she owns 3.

  28. Jeff C. says:

    I have a very healthy maltese. He was 3 years old. Very healthy. I gave it to him he acted weird. I was told later it was a seizure. The vet told me to make sure he had foof. He threw up the second dose. The 3rd dose almost killed him. Within a month his digestive system had potholes according to the internalist I had to take him to. He has to stay on steroids now for life and a prescription dog food. I cannot prove it was Trifexis but it all started with the first dose.

  29. Andrea McGhee says:

    I was just informed by a reproductive spet that I cannot breed my 3 year old female Corgi because I have given her Trifexis. She abruptly cut our meeting short and said ‘that’s it, we are done’ and basically dismissed me stating miscarriage, malformations are due to breeding dogs while being treated with Trifexis. She said it’s all over the warning label. In fact, I see that it only says consult your vet and use caution. I couldn’t find anything else to substantiate this claim. My female has had two doses for the 10-20 lb dog and she is almost 20 lbs… in the last 90 days and none before that for at least a year.
    She is now in heat and I am hoping to breed her but am now worried. My vet never warned against this and prescribed Trifexis knowing I intend to breed my dogs. Any help would be appreciated

  30. Sadie Heinlein says:

    I have had bad luck with trifexis with 2 of my dogs.
    My maltese would get sick and bloody diarrhea everytime she had it. She was only on it for a few months because we realized it would happen the next day after medicating and would last a couple of days.

    We had also began using it for my pomeranian who was going to be bred.
    At 2 1/2 years healthy bitch bred to a healthy stud.
    My vet said the product would be safe and had me give the last dose 1 week before breeding.
    I now have 2 puppies born with one eye each and one has a cleft lip.
    They are 5 months, healthy and happy beyond the deformaties (the cleft lip pup had to be tube fed until old enough to eat solid food), I had to have the bitch spayed so this did not repeat. After everything I went through after using this product I would never reccomend it.

  31. Sue says:

    I am fostering a dog I rescued. She is being adopted so took her in to have her spayed for local rescue. They gave her a comfortis on an empty stomach before her surgery. well she is not the same dog. Very nervous and projectile diarrhea. I would not have let them give it to her had I known. Dr. Roger Welton you are the fool here!

    • Robert shoemaker says:

      No the shelter is the fool, who in there right mind would give a dog comfort is before a sugrey. Have a hard time believing that. There’s a reason you don’t eat before sugrey!

  32. Violet says:

    I’m not saying this through an influence of mass hysteria. Last month I observed my healthy, sprightly young dog go overnight into a vomiting, shivering sick animal. She became afflicted with red skin, chronic and constant severe itching. This came after a dose of Trifexis. I did not search the internet. I took her to the vet who did not confirm my fears, about having given her a poisonous medicine. She was very dismissive about the possibility of Trifexis being the cause, yet that was the only new thing that had been introduced to the dogs ingestion. By the time her next Trifexis dose was due, her symptoms had subsided enough that I tried again. This time the symptoms have returned immediately and more severe, within a day of this dose. I regret very much giving Trifexis to my dog because she is miserable. I had her for one year and she was so happy go lucky. It’s really very upsetting.

  33. Zachery Klausman says:

    i gave my 6 month old Cane Corso Trifexis which we got prescribed from Banfield. We just saw them last week and he was healthy as can be and growing. I gave my poor boy Trifexis at 7PM and at 12:30AM we were playing tug a war when all of a sudden he fell on his side and started yelping I thought maybe he was having a seizure but he stopped breathing I attempted CPR it did not work. He died from fucking Trifexis.

  34. jerry says:

    Trifexis may not KILL every time.. But I believe it has and does screw up a dog sometimes as well. I would never buy recommend or talk anyway positive of Trifexis

    A note to someone I was trying to get help from. >>>

    Hi Heather.. I had never considered that he may be a mix? Possible.. I read Chihuahua’s could weigh between 3 and 15 lbs.. But that was on the internet. Could be miss information..
    Anyway let me give you some history and what we believe happened. To Cause his strange behaviour. Seeing how we observed the changes from a Happy never hostile petto a jekle and hyde..
    When we first got him and upuntil about two years old my wife not only bonded with him, they were like soul mates. She was able to completely potty train him by the time he was six months old. We all got a long great anyone comes over they were always playing with him and holding him. My sister , and our daughter in law espeically.
    Then came Tri-fexus or how ever you spell that poison.. he took one does and was acting all kinds of weird. Fo a day. Vet said we needed to feed him before we gave him that pill, we did and even mixed it with some canned dog food to make sure it did not upset his stomache and then he had this eqispode where he was unbalanced very lethargic and just plain ill.. Following the Experts opinion “our vet” we tried a second pill a month later as scheduled as he said he would probably be ok this time. Well he was worse could not walk for a day..
    Ever since this he behaviour has been bad.. He is still loving most of the time. But not all the time, my sister has actually been bite (snapped at) and my daughter in law as well nolonger attempt to hold him.
    He nolonger does perfect on the potty training often going inside the house. Reading up on this pill seems we are notthe only ones who had trouble.. When we refused to buy it and informed our vet about it they all got very hostile. The vet said he never had an issue.. and ssid his SALESMAN said all that is hype there is nothing wrong with Tri-Fexis. His Salesman.. I said.. really of course your SALESMAN would defend his product.. He has my wife convinced that when we are ready we can bring him in and have him put down..

    So really I do not know what to do.> I either find him a home or I have to come home one day and find out my wife has taken him in… I know this is not your problem.. but thanks for listening…
    My Dog to this day when he is not acting like he has no recolection of us.. is very loving to both of us.. And would jump infront of an intruder for us.. We both know that.. Its just he is unpredictable..
    He is always happy to see us when we have been gone just do not really understand what has happened. But we are convienced it was thr tri-fexis…

    I guess I know what I need to do to keep the peace. Being off work tomorrow.. I may have to and just chalk it up to another death by Tri-fexis. I do not want to isolate him to the garage this winter and how is that living…

    Thanks Jerry

    • J. Kutche says:

      My Chihuahua weighed as much as 7.3Lbs and his death today he weighed 16.8 He took Trifexis 5 years ago immediately started suffering both physical and emotional issues..
      I was convinced that Trifexis was the instrument of his decline. He years since have been difficult, he still enjoyed being around us. But you could clearly see if was not and never would be the same.
      I saw some postings about necessary evil.. Why the hell do we even need Trifexis.. Fleas.. Fleas my ass The major reason for heart worm meds is mostly heartworms.. There are other things to take care of fleas other issues. Which make giving Trifexis a joke and not needed at all..
      DO NOT DO IT.. No reason too…

  35. Mark says:


    Last night, I administers the recommended dosage, with food, to my 2 standard poodles. Each dog is around 60 – 62 lbs both are healthy with no disease. One is a 2 y/o neutered female, the other is a 4 y/o in-tact male. Following the dose they had GI upset and one or both vomited. I did not see who vomited; I only saw vomit on the carpet after the fact.
    Today, they are both sleepy and lazy. Is drowsiness a known side effect of this drug?
    How long should the drowsiness last?
    What else should I watch for?
    A family member has a 7 y/o standard poodle female who has taken Trifexis for years with no problems.
    Thanks for any reply.


  36. Regan says:

    This article is not only offensive, it shows an utter leacknof understanding of Autism as well. Autism doesn’t kill you dumbass, Trifexis does. I have a son with Autism (and no, it wasn’t caused by vaccines, moron) and a dog that died from that nasty poison. She was a beautiful, sweet, loving 2 year old Bichon mix WITH ZERO HEALTH PROBLEMS. She had a clean bill of health in February of 2016. First dose of Trifexis was March 15, 2016. We started to notice she wasn’t eating as much, but she was drinking, so we assumed it was because we were having unseasonably hot weather. Gave her a second, third, and forth dose in April, May, and June. We had difficulties getting her to take it after the second dose, and by June, she was hardly eating anything. Then, not connecting her behavior to this nasty drug, we have her the fifth and final dose on July 15, 2016. She stopped eating completely after this dose. She became lethargic and began running a fever. We took her to the vet and was told she had a “blood infection” and was given steroids and antibiotics to give her. She seemed to improve slightly for a couple days, then just went straight downhill. We took her back to the vet to find out her organs were failing and she had severe internal bleeding. She went from a healthy, happy puppy to dead in 2 weeks after the last dose. I believe the eating less was a result of The Trifexis and we just didn’t know it. Kind of like a lot of my sons Autism symptoms showed FROM THE WOMB and we didn’t know it. For you to compare this poison to vaccines and Autism just shows me you are a complete and total moron.

    • Regan says:

      I apologize, apparently I linked your article to another one that said something about Trifexis being no different then vaccines and sometime vaccines can cause death by Autism. I can’t edit my post or I would take those statements out. I still disagree that Trifexis doesn’t kill, because I’ve seen first hand that it does.

      • Mary Jean says:

        Yes, my dog was on Trifexis 2yrs. And he died from kidney failure. I blame it on the drug and nothing more. I would demand strongly that every pet parent that used Trifexis and had their pet die, please every vet dr. and clinics be notified of the pets that where on Trifexis and died, and a Law Suit should be conducted of the manufacture. Let the World know this drug KILLS!

  37. Terri Glasser says:

    My dog is 13 Large mixed breed. Last night i gave him his 3/4 of dose trifexis and was going to give remainder today to avoid stomach issues. At 5 am he was whimpering and breathing and his back legs (which are week because he is large and elderly) were stretched out behind him and he couldn’t move, reposition himself, or get up. I used a towel to get him out but his back legs kept splaying out, he was yelping in pain and scared. I went to vet concerned it was time to euthanize if couldn’t walk and staff had dr call me. I told her of trifexis dose and she said it may have caused neurological issue. Tonight he is up and walking like normal. As i think back to other times his legs splayed out with yelping and him distraught was after trifexis.

    • Robert shoemaker says:

      3/4 dose? What exactly does that mean. Did you give him his 3rd out of 4 dose or did you cut the pill. As Dr. Roger has stated trifexis is strong meaning if you are giving your pet the doses above his weight range and cutting it into 3/4 then yes i would expect side effects. As I don’t know the entire issues going on…..but I’d love to understand more.

  38. Laurie Mitchener says:

    I have a perfectly healthy black lab aged 8 years old who gets regular vet visits and normal innoculations. After much PRESSURE from our vet I finally caved to monthly Trifexis dosing a year ago. My healthy active lab now has regular seizures nearly every month lasting up to two minutes in duration, no other disease or pathological reason whatsoever other than the introduction of the Trifexis. Her environment did not change, her food did not change, her health did not change, her age is not outrageous and she is otherwise healthy and active. I am a well read and educated individual. I am not prone to mass hysteria and I do my research. I do not trust big pharma and for my own medicines I tend to go the homeopathic route Why didn’t I trust this route for my beloved fur baby. Now I have subjected her to this awful neuro toxin poison and God knows what life from now on. Don’t tell me all these people are crazy and their animals just died from natural causes or became sick for no reason! I call bull hockey.

  39. Lagniappe says:

    As far as I’m concerned, I’m going to stop the administration of Trifexis for my 2 dogs and sytart them on some other kind of heart worm medicine that’s palatable. THEY HATE THE TRIFEXIS.

    One of my dogs experienced vomiting once after one of her doses. I was told to administer after feeding. I haven’t seen her vomit since or experienced any other side effects.

    My problem is that she absolutely refuses to take the stuff. It must taste awful. I’m sick and tired of having to shove it down her throat. I’ve tried sneaking it in peanut butter and every other kind of her favorite foods. She spits the Trifexis out every time. I have to literally shove it down her throat. It’s really upsetting.

    When I shove it down her throat, she clamps down as hard as she can and I usually come out of it with bite scratches on my hand. I’m sick of this medicine and this is the last time I will be using it. Trifexis has lost my faith and my money. Thanks guys.

  40. Susan Standley says:

    My dogs heart was damaged by this drug!!!!!!!!!!!!!!!! I breed and show boxers and I do holter monitors on my dogs as a health screening prior to breeding. Dallas at 17 months (5 months after Trifexis almost killed him) had 17,000 vpcs (with lots of runs) on his holter monitor. Echo was perfect, heart function was normal. 3 more holter monitors were done over the next years span. On meds his vpcs went down to 4,000 with no runs. I hadn’t done a holter in almost 3 years and when I finally did at 6.5 years old his holter showed NO VPCs… I contacted cardiologist and he said to take him off his sotalol, and re holter in a week. I waited two weeks and Dallas had ONE VPC at 6.5 years old! How do you explain this other than the dogs heart was affected by something OTHER than genetics???????? LIKE A DRUG that has KILLED THOUSANDS of dogs and almost killed mine! Elanco needs to be held accountable for this BS! They have made BILLIONS of dollars off of this poison and refuse to do anything to fix it!

  41. Michael says:

    I guess I experienced mass hysteria this morning after I administered my dog it’s first dose of Trifexis. 2 hours later we were in the ER. She experienced trembling/shaking, ataxia, seizure, and hypersalivation. Those symptoms should be familiar to Elanco. It’s in their fine print. She is now recovering after IV and care, and hopefully she has no permanent damage. This is not an isolated case it would seem. Perhaps our dog had a unique reaction to Trifexis, but after talking to our ER doctor I got the impression this is a common experience. A final thought. As a motorcycle mechanic I can advise you which models to avoid, common problems certain models have, proper maintenance to follow, etc. You rarely, if ever, hear this info from the sales people.

  42. Can Trifexus raise my dogs liver enzyme and do you feel it is safe

  43. L S Lewis says:


    We gave our 13 week old Aussie her second Trifexis treatment a few days ago; we accepted the treatment as safe without question since our vet gave it to us. The night after we gave her the pill she was acting strangely, distant and more “bitey” than before, also with some aggression which she had never demonstrated and a frantic fascination to throw the water from her dish everywhere. I did not make a connection to the pill until after researching the consumer reviews of the medicine and am now certain the sudden shift in her personality is due to the Trifexis. Needless to say we will not continue with this treatment. We hope she will return to normal once the drug works out of her system as a full blood transfusion seems the only way to remove it immediately. Hopefully she will not exhibit any additional negative reactions in the meantime. Hopefully.

    Interestingly, we love Comfortis which is made by the same company with zero complaints/accusations online of pet sickness or death caused by the drug. Both our cats react wonderfully to Comfortis, fleas are gone within 24 hours with no apparent side effects.

    My question: Why the drastic difference in two drugs from the same manufacturer? How is due diligence met for one but not the other? Is it pure luck of the draw? I would love to rely on Elanco for my pet medication needs but there is no constant available to create a comfortable relationship with this company. Quality continues to fall behind profitability. Very sad.

  44. Kathryn H. says:

    I would like to preface this by explaining, I am not a “hysterical” person and desire to base my decisions on sound logic, reason, and scientific evidence. I say this to clarify before I am automatically thrown into the mob mentality and mass hysteria you speak of. My question is in regard to the potential danger of the combination of the two active ingredients. You continue to repeat as evidence of the safety of Trifexis, the historical and, current safe and successful use of medications with one of the two ingredients found in Trifexis. As a healthcare professional myself, working with the human population as opposed to animals I truly and simply have no axe to grind but merely, a desire for more information regarding this subject in general.
    I haven’t researched the ‘studies’ and scientific background of the medication, as I am just now becoming aware of this topic specifically, but was curious about potential contraindications and adverse effects of the medication that I was never informed of by my vet.
    I understand fully that causation cannot be determined in many of these cases where there are a multitude of variables that cannot be controlled as they would ideally be in a clinical/ research trial, but my curiosity is in regard to research conducted before and after this medication was brought to market. As someone who identifies as an active pro-vaccination individual who seeks to end these episodes of mass hysteria that potentially cause more harm than good, especially when the people who tend to start such wild fires have no formal education, training, and/or experience with which to be speaking about, let alone propagating such dangerous incendiary ideologies such as that of “anti-vaxxers”. That being said, I hope you understand that my intention is not to approach this topic with emotion and pseudo-science. I am not opposing what you are saying but merely would like more information, as I respect you and your expertise in the profession and study of veterinary medicine. I am not familiar with the FDA guidelines and processes involved with veterinary medicine and am humble enough to admit although I may be privy to human healthcare processes I am less so with veterinary and animal healthcare processes, which is why I would just like more information on the topic. I understand your anger at people jumping to conclusions and hope you are able to look at my inquiry objectively and not take a defensive tone.
    I look forward to hearing from you.

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