Unlike a kid who can cry or whine if he’s feeling lousy, your cat can’t tell you if something hurts or he’s sick. So how can you know when you should take a trip to the vet?

For starters, if you have trouble finding your kitty, he most likely should visit the vet. “Cats generally hide when they’re not feeling well,” says Krista Vernaleken, DVM, medical director at Bulger Veterinary Hospital in North Andover, Massachusetts.

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Besides hiding, keep an eye out for other behavior changes — especially the 13 symptoms that follow:

1. Peeing problems. If Tabby’s peeing outside the box, it’s likely he’s sick, says Vernaleken. Take him to the vet. He might have a urinary tract infection or other condition.

If you’re constantly refilling your cat’s water bowl and notice that he’s spending a lot of time in the litter-box, see the vet. Excessive thirst and peeing can be signs of something that should get immediate treatment, such as kidney failure, diabetes or liver or hormonal issues.

If your cat has trouble relieving himself or doesn’t seem able to pee at all, it could be a serious emergency, says Greg Wolfus, DVM, director of Tufts at Tech Veterinary Clinic at Tufts University’s Cummings School of Veterinary Medicine. This is especially true if he’s a male: He may be obstructed — a life-threatening condition that requires immediate treatment.

2. Runny eyes and nose. Secretions from your cat’s eyes and nose should be checked by a vet. Even if she’s not sneezing, it’s likely your kitty has an upper respiratory infection, says Wolfus.

3. Sudden changes in eating habits. If Fluffy generally is a hearty eater, but suddenly refuses to eat, take him to the vet. He could be suffering from dental disease, a kidney, liver or pancreas problem, a hormonal imbalance or even cancer.

A check-in with the vet is also in order if your cat suddenly seems voracious. Many owners of older cats are thrilled when their pets’ appetites perk up. But it could mean they have diabetes, intestinal problems, parasites or cancer to name a few, says Wolfus.

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4. Breathing problems. Struggling for air, wheezing and making other weird sounds while breathing can signal a life-threatening emergency, including respiratory infection, asthma, bronchitis or heart disease.

5. Diarrhea. Visit the vet if your cat has the runs, advises Vernaleken. Diarrhea can cause dehydration. Also, along with other symptoms such as vomiting, not eating or acting lethargic, diarrhea may be a sign something’s wrong with your cat’s tummy or other organs.

6. Vomiting. Don’t be alarmed by a single upchuck, says Vernaleken, especially if your cat seems fine otherwise. She may have eaten too fast or coughed up a hairball.

But if you kitty throws up more than once in a day, or if she’s vomiting and acting lethargic, get her to the vet. These symptoms could mean a gastrointestinal obstruction, hormonal imbalance, electrolyte abnormality, poisoning, liver or kidney dysfunction, pancreatitis and even cancer.

7. Lethargy or unresponsiveness. Cats sleep a lot and love basking in the sun. But if it seems like Fluffy’s spending more time catnapping than usual, take him to the vet, advises Vernaleken.If your cat collapses or is unresponsive, you have an emergency.

8. A bulging belly. A distended abdomen could be a sign of internal bleeding, a gastrointestinal obstruction or a hormonal disease — all emergencies, warns Vernaleken.

9. Limping. If your cat is having trouble walking, it means she’s in pain. Get her to the vet, advises Vernaleken. Despite their fancy-footed agility, felines can still tear ligaments or fracture bones. Arthritis is another possibility.

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10. Eye problems. If the whites of your cat’s eyes look red or he’s blinking a lot or pawing at his face, have him checked right away. He may have a scratch or an ulcer on her cornea, a detached retina or glaucoma, among other things. “Any eye issue is an emergency," says Wolfus.

11. Ear problems. If your cat is scratching her ears or you notice redness, swelling or discharge in her ear canal, it could be a sign of yeast, ear mites, bacteria or allergies, says Vernaleken. See the vet.

12. Skin issues. If you cat is scratching, licking or biting himself or he’s losing hair in a discreet area of his body, have him checked out, advises Vernaleken. It could be one of a number of skin conditions, allergies, an infection, ear mites, acne or even fleas.

13. Weight loss. Take your cat to the vet right away if she’s losing weight. It could be a sign of cancer, kidney or liver problems, heart disease, diabetes, among other things, says Wolfus.

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In addition to single symptoms, always report combinations of symptoms to the vet. “For example, a middle-aged or older cat who’s rapidly losing weight but has a voracious appetite and kitten-like behavior could be suffering from hyperthyroidism,” says Wolfus.

In general, the best thing you can do for your cat is to get to know him well. Monitor his eating behavior so you’ll notice when there’s a change.

“Watch the litter box and make sure there are feces and urine each day,” adds Wolfus. If you don’t think you can keep this information in your head, create a simple chart so you can keep up. It also can help to put one person in charge of feeding and changing the litter box.

If you feel something’s wrong and it’s after hours, don’t hesitate to call an emergency vet hospital. Always trust your gut. Nine times out of 10, says Wolfus, pet owners are right when they think something’s wrong with their furry family members.

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Daniela Caride is a freelance writer who has four cats and two dogs. She blogs about being a pet parent at Taildom.com and founded a nonprofit called Phinney's Friends.

Daniela Caride is a freelance writer who has four cats and two dogs. She blogs about being a pet parent at Taildom.com and founded a nonprofit called Phinney's Friends.