Loss of appetite

Your pet may skip a meal here and there, but if you notice that he's turned down several meals in a row, he may be trying to tell you something.

"A reduced or absent appetite, especially if it lasts for more than 24 hours, is a reason to bring your animal to the veterinarian," says John Randolph, DVM, diplomate of the American College of Veterinary Internal Medicine and professor of medicine at Cornell University's College of Veterinary Medicine.

Fever

When dogs and cats have elevated body temperatures, you can feel the heat on the insides of their ears. Fever can be a sign of many types of illness, so take your pet to the vet for an examination.

Vomiting or diarrhea

Vomiting and diarrhea are not always signs of illness in pets. She may have eaten something that disagreed with her -- a situation that often can be treated with simple home remedies. But prolonged episodes of vomiting or diarrhea and/or blood in the vomit or stool are serious cause for concern.

Just like toddlers, dogs and cats sometimes swallow strange household objects that irritate their stomachs. "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 and diarrhea also can signal parasitic infection. Any other changes in elimination patterns such as constipation, frequent or infrequent urination, and unusual stools should be examined immediately.

Physical appearance

You pet's physical appearance is a good indication of his overall health. A thick, shiny coat is an indication of good health, while a dull, patchy coat is usually a sign of illness. When you groom your pet, check for any bumps on the skin, which can indicate flea or tick infestation. Mucus or discharge from the eyes, nose or ears is worrisome. Check your pet's mouth. What color are his gums? They should be pink, not pale or bluish. Any change in gum color is a red flag for a more serious health concern.

Changes in behavior

If you notice that Fido is sleeping more than usual, is not as perky or is just generally lethargic, this may mean he is not feeling well. Dogs are pack animals and tend to hide signs of illness, so it is important to be particularly aware of any small changes in behavior.

"Dogs and cats can't tell us when something hurts or doesn't feel good. But the owners who see them every day realize when they're not being their regular selves," explains 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 is a reason to see your veterinarian."

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