Pet Symptoms: 6 Signs of Illness in Your Dog or Cat

What our sick pets can't say in words, they'll demonstrate through physical symptoms and behavior changes.

By Katherine Kam
WebMD Feature

Reviewed by Karl Jandrey, DVM

Monty's behavior mystified his owner, Karen Mitchell. The 7-year-old dog, a mix of pit bull, boxer, and pointer, was long housebroken and rarely had indoor accidents.

So when Monty began urinating in odd places, Mitchell, 43, at first attributed the dog's behavior to the stress of big life changes. Mitchell and her husband had recently welcomed a new baby daughter and had moved into a new house in Alameda, Calif.

But when the urinating didn't stop, a worried Mitchell finally took Monty to the veterinarian after he wet himself during sleep. "He actually slept in his pee," she says. "He wasn't acting out by peeing in the corner because he's mad that we moved. This was definitely a sickness."

Monty's vet delivered a prompt diagnosis: diabetes.

Pet Health: Pay Attention to Your Pet's Symptoms

What our sick pets can't say in words, they'll demonstrate through physical symptoms and behavior changes.

"Dogs and cats can't tell us when something hurts or doesn't feel good. But the owners that see them every day will realize when they're not just being their regular selves," says Mark Stickney, DVM, director of general surgery services at Texas A&M University College of Veterinary Medicine and Biomedical Sciences. "Any change in your pet's behavior from what it normally does is a reason to see your veterinarian."

Pay special attention to cat health, says Julie Meadows, DVM, assistant professor for clinical medicine in community practice at the University of California-Davis Veterinary Medical Teaching Hospital. Cats are less likely to show owners that they're sick, and owners may be less attentive to them because they are more independent.

To help you know what to look for, WebMD asked several experts to provide six "red flags" that should prompt a call or visit to the veterinarian about your pet's health. And as always, if you are concerned about anything at all, reach out to your vet.

Vomiting or Diarrhea

Cats and dogs vomit on occasion, often without being seriously ill. "A puppy who's eating and playful and has been outside eating leaves and junk and vomits and then goes back about his life" doesn't worry Meadows much, she says.

But a pet that vomits, especially several times in one day, acts lethargic, and lacks appetite needs a veterinarian's attention, according to experts.

Another serious pet symptom: blood in the vomit or throwing up digested blood that looks like coffee grounds. Gastric ulcers can cause bloody vomit, and so can swallowing a foreign object that irritates the stomach. Veterinarians tell WebMD that they have treated dogs and cats that have gulped down sharp bones, socks, underwear, mittens, towels, string, tinsel, corn cobs, fish hooks, and toy soldiers.

"I had a dog swallow a steak knife right off the table, like a sword swallow," says Sandra Sawchuk, DVM, clinical instructor at the University of Wisconsin-Madison School of Veterinary Medicine.

Vomiting or diarrhea can stem from many other causes, too, including gastrointestinal illnesses or parasite infections that include hookworms, roundworms, whipworms, or giardia, Stickney says.

Blood in the stool is also a warning sign that a pet needs to see the vet.

To prevent human exposure to parasites, such as hookworms and roundworms, Meadows suggests regular de-worming of pets. That's especially important if anyone in the household has a weakened immune system, such as from HIV or AIDS, or if small children play in areas where pets defecate.