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11 Warning Signs of Cancer in Cats That Every Owner Should Know

Cancer is the number-one disease-related killer of cats and dogs. Many cancer symptoms in cats are subtle and can be caused by another condition, but if you notice any of the following potential cancer warning signs, it's a good idea to talk to your vet.

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cute ginger kitten peeking out of a wicker podAlexandra King/Shutterstock

Excessive hiding

Cats love a good hiding spot, but if you notice your kitty is spending more time under the bed or in hard-to-reach places, it could signal that something’s wrong. “Owners often tell me they notice when their cat is ill if they’re usually social but have been spending more time in new hiding spots, or that they stop coming out at feeding time,” says Jake Zaidel, DVM, founder of Malta Animal Hospital in upstate New York and a member of the American Veterinary Medical Association. While excessive hiding is a general sign that something is off with your cat—not necessarily cat cancer—it’s still a good idea to see a vet, he says. This is what your cat is secretly trying to tell you.

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A skinny Cat image.Aun25/Shutterstock

Weight loss

Weight loss is the number-one cat cancer symptom Dr. Zaidel says he sees. It’s often the sign of a gastrointestinal tumor. “When cats are usually food-motivated but start to turn up their nose and don’t want to eat, that’s very concerning,” he says. Cancer can also cause cats to lose weight while maintaining their regular appetite. If you notice your cat shedding pounds, either rapidly or slowly, make an appointment with your vet. This is why your cat loves your laptop so much.

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Checking the mouth of a catViktoriia Hnatiuk/Shutterstock

Mouth changes

Sores, lumps, a strange odor, bleeding, or a change in gum color can be a sign of oral cat cancer, particularly in older cats. This cancer sign in cats often goes unnoticed for too long. “We commonly find visible oral tumors because people don’t examine their pet’s mouth,” says Zaidel. “Many oral tumors can be really devastating because people don’t find them until it’s really advanced.” He also suggests brushing on a regular basis. It’s a good idea to watch when your pet yawns or eats, advises Timothy Rocha, DVM, an oncology specialist in New York City. See a vet if you notice something out of the ordinary. Find out the 50 secrets your pet is keeping from you.

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Cat nosewiroj Roudkhlay/Shutterstock


Nosebleeds are never normal, says Dr. Rocha. “With an older cat, a nosebleed is particularly worrisome. It can be a sign of cat cancer in the nose,” he says. “With younger cats, I would worry more about something like a foreign object stuck up there before cancer.”

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Cat sitting in a cat litter box or tray.Sharaf Maksumov/Shutterstock

Diarrhea or changes in bathroom habits

Occasional diarrhea usually isn’t a sign of cat cancer, says Dr. Rocha, but if it persists or gets worse, bring your cat to the vet. Excessive litter box use, difficulty peeing/moving bowels, or blood in urine or stool are also potential signs of cancer, according to Pay attention to frequent vomiting—it could just be hairballs or upset stomach, but it’s also a presenting sign of GI tumors, says Dr. Zaidel. This is why cats do that weird kneading thing.

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British Shorthair Cat lying downbloomcloud/Shutterstock


Persistent discharge from the nose or eyes is cause for concern, says Dr. Zaidel. Nasal discharge is a common sign of facial tumors, and eye discharge can signal an eye tumor.

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sleeping catKovanko yevhenii/Shutterstock


Seizures can be a sign of brain tumors in cats, most often seen in older cats with cancer, says Dr. Zaidel. If you start to notice sudden and uncontrolled bursts of activity, like champing and chewing, jerking of the legs, or foaming at the mouth, your cat could be experiencing seizures and you should see a vet immediately, according to Cats can also suffer atypical seizures, which aren’t classic convulsions but instead manifest as fits of strange behavior, like sudden rage or hysteria, excessive licking or chewing, or scratching or biting their owner. If your cat displays these 4 signs, it means that they trust you.

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The white cat sitting and then itching so much that it took the foot to scratch his throat and look like a man who is having a rash as well.Phensri Ngamsommitr/Shutterstock

Skin changes

“Every lump, bump, or skin change should be checked,” says Dr. Zaidel. “It could be benign or cancerous, but it’s always easier to treat the earlier it’s caught.” Feel for bumps, lumps, or swelling as you pet your cat. If you notice something iffy, don’t delay—there’s no way to distinguish between a lump that’s benign or malignant without taking a sample. Also pay attention to any sores that won’t heal or lesions that seem itchy or painful.

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Funny Fat Cat Sitting in the Kitchen and Probably Waiting for some more FoodBenoit Daoust/Shutterstock

Weight gain

Sudden weight gain or bloating can be a sign of cat cancer, specifically GI, in cats. If your cat is eating less but seems to be bulking up, take a trip to the vet, says Rocha. A sudden spike in appetite also warrants a visit.

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tired sick catNatata/Shutterstock

General pain or discomfort

“Pain is a rather substantial sign of cat cancer,” says Dr. Zaidel. If your cat is normally a snuggler but starts to cry out when you pick him up, a doctor’s visit is in order. These are the 17 things your cat would love to tell you.

Reader's Digest
Originally Published in Reader's Digest