Do Cats Get Cancer?

Joanne Lynn Intile, DVM, MS, DACVIM
Published: September 25, 2013
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I am a self-proclaimed “Crazy Cat Lady.” Though I own only three cats, I am fairly fanatical about all things feline and would easily have several more if my husband (and apartment complex) would allow.

If you are a faithful reader of this blog, or even an occasional visitor, I’m sure you would never guess this to be the case, as the majority of the articles I write are centered on dogs.

Although many cancers occur with equal frequency in both species, most of the information I present describes dogs, and even when I use specific cases as examples, I often talk about my canine patients, leaving felines out of the discussion. Why is there such a disparity between my passion (cats!) and the topics I write about (mostly dogs)?

Truthfully, though cancer occurs as frequently in cats as in dogs, and the most common cancers we treat in dogs are the same as in cats, there is far less information available for cats as compared to dogs, and outcomes tend to be much poorer in our feline counterparts.

One reason for this is cats tend to hide visible signs of illness until their disease is significantly advanced. Compounding this is the signs cats eventually do show are incredibly non-specific. The top two signs cats with cancer will show include inappetance and hiding. Yet, cats may show either because they are seriously ill or because they are unhappy with something going on in their environment. How does the average pet owner discern the difference and know when to seek veterinary advice?

Consider a diagnosis of lymphoma, the most common cancer in both dogs and cats. Dogs tend to present with palpably enlarged external lymph nodes owners detect while petting them, where cats tend to develop lymphoma within their gastrointestinal tract, and enlargement of external lymph nodes is rare. This means dogs are typically diagnosed in a relatively asymptomatic phase, whereas cats will be showing signs related to their gastrointestinal tract.

As an example, Duke is a robust 7-year-old tabby cat who up until a week ago Saturday was behaving absolutely normally. However, on that particular weekend evening, this otherwise food motivated feline missed his evening meal, and when his owner went to look for him, she found him hiding under her bed. She recognized his signs as abnormal and brought him to the emergency service at our hospital for evaluation.

Duke’s exam was relatively unremarkable, however further diagnostics showed he had a large amount of fluid within his abdomen, multiple enlarged internal lymph nodes, and a large mass encircling a portion of his intestine. Further testing confirmed Duke had lymphoma.

Less than one week passed between Duke showing any signs of illness to me telling his owner that without treatment he would likely succumb to his signs within a few short weeks, and with treatment we would hope to see him survive anywhere from six months to two years.

Unfortunately, Duke’s diagnosis of lymphoma could easily be replaced with any number of cancers afflicting cats, including mast cell tumors, intestinal adenocarcinomas, injection site sarcomas, and even many non-cancerous conditions (e.g., diabetes mellitus, a foreign body, etc.).

With any cancer, we feel the more advanced the disease is, the less successful the treatment will be. This may be one simple reason why a diagnosis of cancer is so devastating for our felines; by the time they are diagnosed their disease tends to be extensive. For those cases where we have treatment options, there are several other hurdles particular to cats that I think are worth mentioning.

Consider the necessary literal “capturing” of cats that is required to bring them to a veterinary appointment. Dogs are typically used to going for walks and car rides, and even those anxious about visiting the vet are still initially easily duped into traveling without much protest. Cats must be caught and transported in carriers, and for some, this seemingly innocuous act may preclude the option of treatment altogether.

Next, consider that the medications prescribed to prevent or alleviate side effects from treatment, or even some of those used as chemotherapy for specific diseases, are most commonly made in oral forms. The administration of oral medications can be an impossible task for some owners, which can make treating adverse signs or certain forms of cancer impossible.

Cats undergoing treatment with chemotherapy are prone to decreases in appetite, and developing a very picky appetite. This causes a great deal of anxiety in some owners, and can even lead to premature cessation of treatment, due to the perception that the cat is not thriving while on treatment, despite the effects not being life-threatening.

Each of these factors (among many others too lengthy to record in one simple article) contributes to some of the frustrations I experience regarding cats and cancer. I’ve often joked that I should form a support group for owners of cats with cancer as their needs truly are so different from their canine-owning counterparts.

As a cat-centered person, I feel I’m more likely to embrace the challenges of treating felines. Or perhaps the challenge of the treatment is what makes me love them so much more. My goal in writing this is to stress that my lack of writing about cats represents nothing more than a bias in available information within veterinary oncology.

Fortunately, I know my feline patients will never take this personally, as so accurately stated in one of my favorite quotations about kitties: “As anyone who has ever been around a cat for any length of time well knows, cats have enormous patience with the limitations of the human kind.”

Dr. Joanne Intile

Image: Kurhan / Shutterstock