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Saddle Thrombus In Cats

The largest artery in the body that is the main “highway” for the propagation of oxygenated blood from thr heart to the tissues is the aorta. The feline aorta leaves the heart with oxygen rich blood and courses through the chest and ultimately through the abdomen heading toward the tail. At the level of the pelvis, the aorta splits into two smaller arteries that ultimately supply blood to the tissues of each leg. It is at this split where formed clots can get lodged, leading to a severe medical emergency called a saddle thrombus.

Saddle thrombus is exclusively a feline phenomena, causing a severe situation where the lodged clot cuts off blood supply to the legs. The lack of nutrient rich, oxygen rich blood reaching the tissues of the legs leads to severe pain, disuse of the legs and severe damage to the tissues, blood vessels, and nerves.

Typically, cats that are predisposed to saddle thrombus have underlying cardiac disease that increases turbulence to the flow of blood through the heart. This increased turbulence makes these patients more prone to the formation of clots. Cats with hyper-thyroidism are prone to a cardiac condition called hypertrophic cardiomyopathy. Therefore, saddle thrombus tends to be associated with cats that have hyperthyroidism.

Cats that have formed a saddle thrombus typically appear paralyzed, unable to move the rear legs. They are often vocalizing due to severe pain. When touched, the back legs are often cold and stiff, and sometimes there is panting and trouble breathing.

Due to the time sensitive nature of the irreversible consequences of saddle thrombus, as well as the severe pain that saddle thrombus causes, it is strongly recommended that one seek immediate veterinary care for one’s cat if saddle thrombus is suspected.

Saddle thrombus is diagnosed by a combination of history, presentation, cold/stiff rear legs, and lack of any palpable pulses in the rear legs. Chest x-rays will often indicate evidence of cardiac disease, and even congestive heart failure.

Prognosis is poor for saddle thrombus, even when found early. Treatment is geared toward managing pain and re-establishing blood supply to the legs through the use of IV clot busters such as heparin, or surgical removal of the clot. In many cases, however, the damage to the tissues, blood vessels, and nerves of the rear limbs is too severe and irreversible for treatment to offer a return quality of life, leaving euthanasia the most humane option for the patient.


Roger L. Welton, DVM
Founder and Chief Editor,
President, Maybeck Animal Hospital

CEO, Dr Roger’s Holistic Veterinary Care

Article updated 6/3/2014

26 thoughts on “Saddle Thrombus In Cats

  1. Lillie Taylor says:

    This week I had to make the horrible decision on what to do for one of my kitties. After being told that his heart was enlarged (not sure if that was from the beginning of his life or something that happened recently…I’m not a medical professional so I don’t know how that happens) and had a small amount fluid on his lungs along with the diagnosis of saddle thrombus we chose to humanely let him go. I could not imagine letting him live in pain since pets can not vocalize to us when something is wrong or risking him having another clot or some worse heart condition while we were at work and leaving him to suffer alone for hours. We were fortunate to be home when it happened this time and got him to the vet immediately. Sorry for the long story to get to the point of my post, but he is one from a litter that we fostered from kittens and decided to keep 3 of them. His sister passed away 3 years ago from some kind of unknown neurological issue. At least this is the only answer our vet could find. We now have only 1 of this litter left and he is 12 years old. It makes me very apprehensive that there is something in all the kittens from that litter (paranoid fur-mommy). Would a pre-emptive x-ray tell us anything that would help if the remaining kitty has a similar heart issue? Is there a medication he could take that might prevent a clot or is that even too dangerous to give them?

  2. Laurie says:

    This evening, I lost my beloved Odysseus to saddle thrombus. We made the decision to end his pain and it was so very hard to let him go. He was my very special cat friend and I will miss him dearly. He was 10 years old. This article is a spot on description of the symptoms and helps me to understand what happened to my little love. It also reassured me that we made the right decision. Thank you

  3. Cherie says:

    Saddle Thrombus is not necessarily only for cats. Ferrets will also be afflicted by this. It’s just as horrific for them. I just had one go through this two nights ago.

  4. Hannah mae says:

    I lost my dear tabby cat Joey to this this morning. At first I thought he had been hit by a car until I sadly found out the severity of it at the vets. I made the decision to put him down he was only 3 years old and I shall miss him dearly.this gives me understanding of what has happened and has been such an awful shock for us. Didn’t expect to loose him this soon it’s such a sad thing to happen and so rapidly. He seemed fine last night and then by morning couldn’t my little man ,x

  5. Lee says:

    Lost my lovely cat max on Sunday to saddle thrombus . I’d taken him to vets both previous days ( he was also on thyroid medication) because he’d been sick and breathing wasn’t quite right. He was given antisickness injection and steroid . He woke up Sunday I thought he was looking and feeling better when he was suddenly sick then howling and could not walk .Had to wait for an hour for vet to get to surgery . It was terrible . Nothing could be done so he was put to sleep . I can’t get over the shock miss him terribly . R I p max love you x

  6. Janice says:

    Just lost my little Belle (13) to saddle thrombus. Her brother, jasper(11), had it two years earlier. In both case I was woken up in the wee hours of the night by a screaming cat. The male was completely paralyzed in the hind end and Belle partially. Both had to be euthanized.

  7. Sue says:

    I lost my beloved 13 year old kitty, Sammy, to saddle thrombus on Saturday, October 10, 2015. He was the light of my life, a joyful purr kitty with a big personality. He had a heart murmur that we have been treating with medication since he was a kitten. He work us up at 7 a.m. on Friday howling in pain and we realized his back legs were paralyzed. We got him to the vet within 30 minutes. However, by Saturday morning he was in severe kidney failure and his temperature was dropping. We had to say goodbye to my sweet little buddy, the toughest day of my life. My husband and I are thankful that we were both home when it happened so that we could quickly get Sammy help. It’s a terrible thing…moments before he seemed perfectly fine.

  8. Lynda says:

    I lost my Mr. Pretty Boy from Saddle Thrombus on Friday morning. I had no idea that he was sick. It came so quickly.

  9. Lorrie says:

    I have tears in my eyes reading all the posts regarding saddle thrombus. I had never even heard of this condition until last night. My cat was eating, walking and breathing fine and in the blink of an eye, I heard this loud howling. I thought Jelly was locked in a closet and I checked all the closets and found him lying in a doorway on his side, gasping for breath and howling the loudest howl I ever heard. We immediately wrapped him in a blanket and took him to an ER vet. He was diagnosed with saddle thrombus and had to be euthanized. I can’t even put into words how heartbroken my husband and I are over Jelly’s demise. It would be different if we knew he was ill, but to be fine one minute and incapacitated the next is beyond my comprehension. Jelly was ten years old. We rescued from the woods when he was two years old and was the joy of our lives. RIP Jelly and all the other cats whom have been taken by this condition.

    • Kim says:

      Lorrie, I’m so sorry for your loss of Jelly! I lost my 11 1/2 year old cat, Rocky, early Saturday morning. Likewise, he seemed fine. He had come in to lie on the floor and started panting a few times. I knew this wasn’t normal, so I started talking to him. He stopped panting and seemed ok. He rolled over on his back and then back to his stomach. Suddenly, he tried to get up, but his rear legs were paralyzed. I was alarmed! Fearing a clot, I took him to an emergency vet clinic. I figured they’d put him on an IV and he’d be ok. I was so totally devastated by the Saddle Thrombus diagnosis! I had never heard of it. After some discussion, the vet said the most humane solution was euthanasia. While it killed me to have to do that, I knew it was the best thing to do. I too am stunned and so broken-hearted. He was a sweet boy, who’d been very clingy lately. Maybe he was trying to tell me something? Prayers for you and all of us who’ve lost a pet to this devastating condition. The emergency vet said there was nothing I could’ve done to prevent this, nor was there anything I did to cause it.

      • Lorrie says:


        I am so very sorry to hear about Rocky. It may be a coincidence, but Jelly, too was very clingy a couple weeks before this devastating condition caused his demise. I cannot stop hearing his howling in pain and reliving this horrific experience. I hope time will heal for all of us here.

  10. Debra says:

    I lost my cat on 25th October to Saddle thrombus too. Scully was fine no health problems at all she still looked like a little kitten even though she was almost 18 years old she even had perfectly healthy teeth. She was with me constantly and it’s hard to accept that she was perfectly fine then I had to make the decision to put her to sleep but I know I couldn’t have watched her suffer. This is the most horrific thing to happen It’s just so sudden and unforgiving.

  11. Pete says:

    We lost our Tux man this past Thursday October 29,2015. I put him outside that morning before going to work and he seemed fine. When I got home that evening he was laying next to the house. When I went to check on him I noticed he had defacated on himself and had flies and maggots on him. I picked him up to clean him and noticed his rear legs were not working. We took him to the vet and they informed us he had saddle thrombus. After reading of this medical issue and where the animal is in severe pain my heart was broken realizing this most likely occurred early in the morning and he suffered all day and I wasn’t there for him. Tux was only four and he had just been treated for ear mites with steroids and was given his rabies shot two weeks prior. I thought he was under weight but the vet didn’t seem concerned about his weight. He will be truly missed.

  12. Sheila says:

    I just lost my 4 year old rescue cat Smokey this past weekend from this horrible condition. He woke me up in the middle of the night howling and unable to move his back legs. I took him to the animal ER immediately. After pain meds the X ray showed he had an enlarged heart and was in CHF. Because of the severity of his condition his long term prognosis was poor. I patted his head and talked to him while he was put to sleep. My heart is broken, but I feel I gave him a final act of love by letting him go before he suffered further.

  13. Lorrie says:

    Pete, I’m so sorry. You can’t feel guilty that you were away. This could have happened at any time. I was just fortunate that I was home when it happened but I still cannot get it out of my head. It will take a long time for us to heal.

  14. Kevin says:

    2 nights ago we lost our beloved Mozart to saddle thrombus. Mozart was my buddy for 15 years, and the loss is devastating. Mozart seemed his normal, happy self when we got home in the evening after work. He showed no signs of trouble or anything wrong. Shortly before bed, I was in my home office and Mozart walked down the hallway past the door. He seemed fine, and then he walked back and plopped down in the doorway, not a place he normally rests. Throughout his life, Mozart always had a way of telling me that something wasn’t right, and him laying there, and looking up at me was his sign. I started talking to him, asking if everything was okay, and when I walked over to him and he tried get up, and that’s when I noticed he had very limited use his hind legs. Mozart had a history of urinary tract problems, but this was something new. He started to make his way, dragging his feet, down the stairs, and I grabbed him. He then vomited more than I had ever seen him do before. My wife called the emergency animal hospital who said to bring him in immediately. At no point right before it happened, and during the ~25 minute car ride to the animal hospital did he ever scream out in pain. He was meowing and clearly distressed, but no loud cries. When we got to the hospital the vet told us the news that is was saddle thrombus and the prognosis was poor. Devastating. They put him on pain medication, and we were able to spend some time with him before they put him down. When he was on the table, he would try and stand up, but unlike only one hour before, he had no use of his back legs, and they were so cold, it was truly heart breaking. When they put him down, we both were there, and we held him, and talked to him, and we shared some final moments together. Mozart was always so loving, and loyal, and we were truly the lucky ones that he chose us to be his owners. It all happened so fast that it has been difficult to process. Like other people have mentioned on this forum, he seemed fine one minute and just over an hour later or so later we were saying our goodbyes. My heart goes out to all the loving cat owners on this forum whose beloved kitties were taken away from them because of saddle thrombus, hang in there.

    • Lorrie says:

      My heart goes out to you. My Jelly laid in the doorway as well, as he always did waiting for his Dad to come out of the shower. That is when he began a howling that I will never forget. This happened three weeks ago and although I can accept his passing, I can’t get the torture he was going through out of my head. It gets a little easier each day but never goes away. Think of all the good memories you had with Mozart and that you gave him the best home he could have ever had. That is what keeps me going.

  15. Cheryl delos Santos says:

    My Dante’ (3 years old) was fine this morning around 7am, Then around 9am my granddaughter said Dante’ couldn’t move his legs. He doesn’t meow like most cats do, but he was meowing just meowing not crying in pain it was like he was frustrated that he couldn’t move his hind legs. Took him to the Vet partly diagnosed with Saddle Thrombus. They took X-rays and blood work. The X-rays did not show any damage whatsoever. The blood work came back normal. They gave him two shots steroid and pain. Then Plavix and Baby Aspirin. It’s along shot but it’s worth trying. He’s not in pain. If he was I would have made the decision to put him to sleep. We will try this for 3 days

  16. Britta Hardesty says:

    My 14 yr old cat is having similar, but not the same symptoms. She’s not in extreme pain as others described, but her hind legs aren’t working properly. It’s been degenerating over the last week. I took her to the vet initially because of blood in her stools and a week later she can only drag herself around. The vet thinks the two things are unrelated. Blood levels are normal, xrays are normal (well, some arthritis for my older, indoor, 6.5kg kitty). What do I do, can anyone provide any advice? The vet sent me home with her this weekend and I’ll go back on Monday and try an xray with iodine to look for subtle spinal issues that haven’t shown up yet. Any advice most appreciated. She’s in some pain if you help her move, she can void her bladder/bowels though sometimes with a bit of difficulty. She’s been on science diet metabolic or indoor or other limited food for a decade due to her weight. I don’t know what to do. thanks for any advice/feedback.

  17. Britta Hardesty says:

    Oh, and she does not have diabetes…

    • Lorrie says:

      I’m sorry you are going through this with your kitty. I do know that when my cat Peanut had acute renal disease, his back legs were very weak. However, you said the labs were negative. I would go to another vet for a second opinion. Please keep us posted!

  18. Minda says:

    We lost my husbands cat Ram who was 15 to this horrible condition in May. It was very similar circumstances to what everyone has described. The sudden collapse and howling and thrashing and rolling but no function in back legs. We rushed him to the emergency vet where he was quickly diagnosed and pts. Poor boy was so scared and in pain… Really no choice but to relieve their suffering. The main reason I came upon this post was because at the end of October my cat Dickens was pts after a couple months of unknown illness with nothing indicated in blood and urine tests but he developed sudden huge kidneys and renal failure. I have been searching and searching what could have happened to him. It is just a sick and horrible coincidence or was is related somehow even though they were completely different. Was it different manifestations of fip? I’m just lost. He was only 6 1/2 and I’m out of my mind with grief for both our boys. Bless you all in the sorrow of your losses.

  19. McKenzie says:

    My poor little Bailey (who was only 4) developed this condition on November 25th. I got home from working the overnight shift at work, to find him in his hiding space in the basement, making this horrible meow. I picked him and and he started to purr and it was then that I realized his back legs weren’t working.

    Bailey was rushed to the vet where he was diagnosed with saddle thrombus, and I was informed the only humane option was euthanasia. I found him at 9:00 am and by 10:30 he was gone. My boyfriend left for work at 7:00 am that morning, so that leaves two hours where he may have been suffering. I feel guilty that I wasn’t there, but am glad that at least he had the company of our other cat Birch. I miss and love him so much.

  20. Danielle says:

    I just lost my baby boy Frodo (5 years) this morning to Saddle. He lost complete mobility in both back legs. he seemed perfectly fine the day before. The Vet had diagnosed he and his brother with diabetes months before, and while they both were on medication, it only seemed like Sam was making progress. Frodo still could not put on weight. I wonder if he was misdiagnosed. Either way, this condition came out of nowhere, and I made the painful decision to put him down. He passed peacefully on my hand. RIP my little love. I will miss you pawing at my face in the morning <3

  21. Jenny says:

    My beloved Houdini…as I sit here in the vets office I researched the prognosis of this unknow and unfair disease. Why would this happen to us and why now? I don’t know…but I know I can’t take seeing you in pain. I’m so sorry kitty, I will forever love my Houdini, I guess this one is the last of your disappearing acts. See you soon baby

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