Most cats are more likely to be obese than underweight, especially if they live indoors. When a cat begins losing weight without any special effort on the part of the owner, it usually signals a serious health problem that must be addressed. Weight loss can be caused by a number of issues, some easily remedied and others more complicated chronic conditions.
A low-quality cat food may not give your cat the proper nutrition to support his activity level. Even if you feed your cat a premium cat food, he may still be nutritionally deficient if a large percentage of his calories come from other sources, such as scavenging outside or in the garbage.
Intestinal parasites can frequently make their home in a cat’s digestive tract, causing diarrhea, vomiting and a loss of appetite. Luckily, these pests can be eliminated with deworming medications.
If your cat has undergone a major change recently, such as a new home, new pet or new baby, stress could be causing her to lose her appetite. Spend time reassuring your cat in a comforting tone that everything is all right, and go out of your way to spend one-on-one quality time with her every day.
Inflammatory Bowel Disease
Inflammatory bowel disease (IBD) is a chronic condition that can affect the small or large intestine and cause vomiting and diarrhea. This prevents your cat from reaping the nutritional benefits of the food he eats. IBD can usually be controlled through a change in diet and limiting exposure to certain irritants and allergens. Sometimes cats may also need corticosteroid treatment.
Diabetes in cats is caused by an overactive thyroid gland that can interfere with the proper metabolism of sugars and is characterized by excessive thirst and urination. The cat begins to excrete the nutrients from her food before her body has a chance to absorb them, so she loses weight despite being extremely hungry. There is no cure for diabetes, but daily insulin injections can keep blood sugar levels in check. Dietary modifications may also help.
Liver or Kidney Disease
Older cats are especially prone to liver and kidney disorders. Because these organs are responsible for removing waste and toxins from the body, when they cease to work properly, toxins can build up in the bloodstream, causing vomiting and diarrhea. Liver disease will also cause a yellowing of the eyes, ears and gums, and kidney disease may cause a change in urinary habits. These conditions are irreversible, but a diet change along with daily medication and fluid administration can keep the symptoms under control.
Feline Leukemia Virus/Feline Immunodeficiency Virus
Cats who spend time outdoors are exposed to unvaccinated strays that may carry feline leukemia virus (FeLV) or feline immunodeficiency virus (FIV). These two incurable diseases are transmitted through blood and saliva, usually during a fight, and are eventually fatal. That said, there are many cats who live long, comfortable lives despite being infected, although they are more susceptible to other infections.