Cat Allergies: Cats, like humans, can suffer from a wide range of allergies. The most common allergy among cats is flea allergy. As cats get older, their sensitivity to flea bites increases. Food allergies account for another 5-10% of cat allergies. Food allergies might manifest themselves as dermatitis and severe itching, or vomiting and diarrhea, but may take up to 10 years to show up.

Vomiting: Some cats vomit all the time, while others rarely do. One of the most common reasons for vomiting is hairballs. All cats benefit from regular brushing to help minimize shedding and ingestion of hair. To check to see if your cat has vomited as a result of hairballs, examine the vomit carefully for small grayish pellets or lumps, regardless of your cat's hair color. Hairballs can occur even with shorthair cats. Another reason for vomiting might be that your cat is allergic to its food. Try switching to another brand with substantially different ingredients and no food colorings to see if that helps. Sometimes cats vomit when they have worms. Consult your vet for a worming appointment. Periodic throwing-up can also be a sign of an overactive thyroid or kidney infection. This is particularly common in older cats. Your vet can do a blood test to find out about either. You know your cat's habits. If it vomits more than usual or in some way demonstrates a departure from its normal habits, take it to the vet. The main thing is to give it plenty of fluids so it does not become dehydrated.

Diarrhea: If your cat has persistent diarrhea, you can try changing its diet. You can try boiled rice, cottage cheese, bread, plain yogurt, boiled chicken, chicken broth or strained meat. Choose the ones your cat prefers. If symptoms continue for more than two days, take your cat to the vet with a stool sample. You should also call your vet immediately if your kitten is weak or listless, or refuses to take fluids.

Feline Urinary Syndrome: (FUS) Feline urinary syndrome, or FUS, is an inflammation, irritation, and/or obstruction of the lower urinary tract. The inability to pass urine can become a life and death situation if not treated quickly. FUS is far more common among male cats than females. Your cat might have FUS if it strains to urinate, has blood in the urine, makes frequent trips to the litter box with only small amounts voided, or forgets how to use the litterbox.

Diabetes: Diabetes occurs in cats who cannot properly regulate their blood sugar level. Symptoms may include excessive thirst and urination; loss of weight or obesity. Older cats are more likely to develop diabetes than younger ones. Diabetic cats should be kept indoors to prevent accidental feeding that could elevate its blood sugar.

Feline Immunodeficiency Virus: (FIV) Though this disease is related to HIV, it is NOT possible to contract AIDS from a cat with FIV. FIV is passed through open wounds such as cat bites, resulting in an impaired immune system. As there is currently no vaccine for this disease, FIV-positive cats should be kept inside and away from other cats.

Upper Respiratory Disease Upper respiratory disease will manifest itself in your cat by cold or flu-like symptoms, like a runny nose and sneezing combined with reddened, runny eyes.

Feline Herpes Virus: Don't worry, you can't get herpes from your cat! FHV affects only cats.

Chlamydia Psittaci: Chlamydia is a bacteria-like organism that inhabits the tissues around the eyes. The most common symptom is conjunctivitis, which is generally seen in one eye at first, then spreads to both eyes.