Symptoms of Cat Diseases

Appetite

• The most prevalent sign that something is wrong with your feline is a sudden loss or change in her appetite. In order to diagnose this, you must be fairly familiar with the animal's eating habits---some cats regularly eat more or less than others. However, if you notice that your cat is suddenly refusing to eat at all, something may be wrong.
  If your cat appears to be in pain when chewing and lets her food dribble onto the floor, when she is normally fastidious, this may be a sign of a mouth infection or ulcer.
  If your cat is suddenly eating twice as much as she normally does, but does not appear to be gaining any weight, this can be a sign of a stomach ulcer, or a build-up of hair in your cat's stomach that will need removal.

Hiding

• If your cat is usually friendly and outgoing, a sudden change in temper may be indicative that she is ill. If she hides in unusual places in the house, does not let you pet or hold her as normal and refuses to go outside if she is an outdoor cat, this may be a problem. Be on the lookout for other symptoms to find out what the problem may be.

Third Eyelid

• Protrusion of your cat's third eyelid when she is awake can be a sign of an eye infection, dehydration, or weight loss. This can also, in more severe cases, be an indication of a tumor or cyst forming behind the eye. Watch for discoloration of the third eyelid, squinting and tearing in your cat's eyes, or frequent changes in your cat's pupil size that do not appear to be caused by light alterations.

Urination

• If your cat howls while urinating, this may be a sign of a urinary tract infection or, if your cat is older, it could be an early sign of kidney failure. If your cat is urinating around the house or in unusual locations, when he has always used the litter box in the past, this may be a sign that your cat's stress level has increased. If something has changed in the household recently (addition of another pet or human) this could be the cause. Otherwise, it may be a symptom of illness.

Vomiting

• Cats vomit regularly as a way to clean hairballs from their stomach. He also may vomit if he has eaten a meal too quickly, if he has tried to play or run directly after eating, or if he has recently consumed plant-life such as grass or leaves (cats do this as a way of regulating their digestion). However, if the vomiting occurs frequently and not always necessarily right after meals or play, this may be a symptom of a problem with your cat's digestive tract.

Discharge

• If your cat is sneezing frequently, suffering from a runny nose, and has patches of ulceration in his mouth, he may have the flu. If this is accompanied by a lack of appetite and extreme lethargy, it may be a more severe variation of feline flu, or an upper respiratory tract infection. Use cotton wool in warm water to wipe fluid discharge from his nose and eyes, and encourage him to drink lots of water.

Diarrhea

• Diarrhea is generally uncommon in cats unless they are suffering from an internal problem. One cause may simply be that your cat has eaten something that does not agree with it. Keep in mind that adult cats are mildly lactose-intolerant. If you give your adult cat a saucer of milk or a large piece of cheese, diarrhea may be the result.
  However, if you know your cat has not eaten anything unusual, and his symptoms persist, you should take a sample of the diarrhea to your vet for testing. It could be a sign of parasites in his stomach or gut, or an intestinal infection.