I was chatting with an owner at the cats-only boarding facility about various health issues, and the topic of cancer came up. “How do you know if a cat has cancer?” he asked me. I was stumped for a moment, then managed to say that it was probably the same way we figure it out in humans. Biopsies and blood tests.
Just to be sure, I did some research. Yeah, I’m the sort of person where if I don’t know the answer to a question, I’ll find it.
Cancers that present as tumors on or near the surface of the body are the easiest to notice — and often the least invasive to diagnose. You see a weird growth, you go to the vet, the vet checks it out. Easy to find, easy to diagnose. But not all cancers are that obvious.
Other types of cancer often have symptoms related to the affected parts of the body. A pet with intestinal cancer, for example, may show digestive issues — blood in the stool, or problems pottying. A brain tumor may cause dramatic changes in behavior.
There are some types of cancer that come with rather vague, generalized symptoms like loss of appetite, a bloated stomach, and weakness (all symptoms of liver cancer in dogs). Symptoms like this can come from a wide variety of health issues — not just cancer.
If your vet does suspect cancer, there are a number of tests that can be used to confirm a diagnosis. Some are similar to tests used to confirm cancer in humans!
- X-rays are often used on pets where MRI or CT (computed tomography) scans are used in humans. More advanced imaging is not widely available for veterinary medicine right now.
- Ultrasound imaging is often used to look at organs — and as a guide for extracting fluids for testing.
- Lab analysis of tissue and fluid samples can look for cancer cells — ones that are different from cells the body produces normally. Molecules called tumor markers can help determine how far along a cancer is.
Cancer staging — figuring out how far along the cancer is — is an important step in determining treatment. Early-stage cancers may be treated differently from late-stage cancers, depending on the type of cancer, location of the tumor, and other factors.