Dog or Cat Having a Tumor Removed? Don’t Make the Mistake of Refusing to Send it off for Analysis.

I diagnose tumors almost daily, some which I determine to likely be benign (not cancerous), some which I determine to likely be malignant (cancerous). For cases that I recommend surgical removal of the tumor, as I hand the client the treatment plan (which also itemizes cost), I am commonly asked to not send it off to the lab for analysis as a cost saving measure. Although saving cost is the main drive for this request, the client commonly rationalizes that if it came back cancer, there is nothing that can be done about it anyway, right? While there may be some merit to this sentiment in cases of highly aggressively malignant cancers, in most cases, the pet owner that declines the biopsy analysis usually lives to regret it.

Here are the itemized reasons why I would recommend sending off any tumor that is surgically removed from your dog’s or cat’s body:

1.) Potential Peace of Mind – If the tumor comes back reported completely excised and it is either benign or a minimally aggressive cancer, the prognosis is good to excellent. The case is put to rest, and the owner may live in peace, not having to walk on egg shells with the fear that a cancer may spread, grow back, or resurface elsewhere in the body.

2.) In many cases when tumors are removed and determined to be cancer, follow up treatment may significant prevent the recurrence of the cancer, or at least provide significant remission period with minimal side effects.

3.) Some dogs are tumor prone, but the tumors they form may not be related. In the case of tumors found to be benign or minimally aggressive cancer, future tumors may not be related. Without knowing the identity of past surgically removed tumors, it is impossible to even hypothesize whether there is a correlation. Thus, removal of future new tumors may be justified, but on the other hand, they may not be.

4.) If a tumor is determined to be aggressively malignant and the prognosis is poor to grave, the pet owner may know this to prepare for what is to come, which organ systems will be the most likely to be compromised first, and how they may monitor their furry companion to know when metastasis (spread of a primary cancer to other regions of the body and organ systems) may be occurring. As a team, the veterinarian and the pet owner can better monitor the patient and predict when it is time to step in to engage in palliative treatment to possibly slow the spread of the cancer or at least maintain comfort and quality of life for as long as possible. We may also better know when it is time to elect humane euthanasia.

I will leave you with a recent example, the very case that prompted me to write this post. An 8 year old female Spitz mix had a tumor removed from her upper arm at another veterinarian in town. She had declined the lab analysis of the mass, using the rationale that I discussed earlier in this post.
After a new tumor formed 8 months after the original surgery somewhat further down the arm, the owner brought the dog to see me, and through fine needle aspirate and microscopic analysis of the aspirate smear on a slide, it was determined that the mass was a soft tissue sarcoma. These types of tumors are malignant and locally destructive, but more often than not, are curative with surgery, if complete surgical resection is anatomically feasible.
The problem was that without previous surgical margin analysis, nor the identity of the previous mass being known, it could not be known if there was a relation between the previous tumor and this new one.

As such, I had to treat the scar from the previous surgery as a potential source of malignant cells, and extend my incision to resect not only the tumor, but that region as well. At 8 plus years of age, I determined that risking a more aggressive surgery than necessary would be a better option than being less aggressive, and potentially putting the dog through a second surgery.

In the end, I resected the mass and previous surgery scar site successfully with clean margins. The old scar tissue was free of cancer cells. The prognosis is good of this dog, but in the end, it seems that the old tumor and this new one were not related. I ultimately did not need to get as aggressive as I did. The end result is still good, but had the owner had the previous mass sent off for analysis, she may have saved significant cost and unnecessary discomfort for her dog.

Dr. Roger Welton is the President of Maybeck Animal Hospital in West Melbourne, FL, Chief Editor of the Veterinary Advice and Information Website, Web-DVM, and founder/CEO of Dr. Roger’s Holistic Veterinary Care.