Causes of Weight Loss in Cats

Weight loss in cats may be caused by different factors, ranging from a change in diet to parasites or diabetes. Anxiety and stress may also cause weight loss. If your cat loses more than 10% of his body weight, you need to call the vet.

Change in Diet

Cats are very sensitive and if you make any minor changes in their diet they may refuse to eat, causing weight loss. Consult your vet to get a few dietary supplements to increase your pet's appetite.

Intestinal Parasites

Intestinal parasites irritate the stomach and the intestinal lining, and will cause chronic vomiting and diarrhea. This will lead to weight loss, if the parasites are not eliminated. Also, if the cat is infected with a tapeworm, this will feed on the food the cat receives, so the cat will be deprived of essential nutrients.

Other feline parasites that are located in the intestines include hookworms, giardia or coccidia. All these can be treated with dewormers.


Diabetes is an endocrine condition; the body has an insulin deficiency or cannot metabolize properly the sugar in the blood.

If undiagnosed, diabetes will cause sudden weight loss in your cat. Other symptoms that you should look out for include increased thirst, frequent urination, bad breath and lethargy.

A diabetic cat should receive insulin shots for life and the cat should gain back the lost weight.


The feline leukemia virus disease (FeLV) is a fatal condition in cats. Symptoms of the FeLV include fever, weight loss, lethargy, enlarged lymphatic nodes, difficulty in breathing and pale gums and mucous membranes.

The leukemia virus can be contracted through saliva, urine and other bodily secretions from infected cats, but can be prevented by FeLV vaccination.

Irritable Bowel Disease

Irritable bowel disease (IBD) may cause lack of appetite, frequent vomiting, diarrhea and weight loss.

IBD is a disease that affects the upper part of the lower intestines; these are swollen and irritated. IBD can be treated with diet food and by eliminating possible stress factors.

Liver Problems

The liver is a vital organ that helps in the digestion process. If the liver is affected by diseases such as hepatitis, cancer or increased toxicity, the cat may lose weight.

Liver disease is signaled by yellow eyes, vomiting, diarrhea, depression and foul odor breath.

Kidney Disease

Kidney disease may cause weight loss; the cat's body is not able to filter nutrients. Kidney disease is caused by infections or cysts and can be reversible with wet diet and medication. However, if the disease develops into kidney failure, the condition is permanent.

Dental Problems

If a cat has dental problems such as injuries or lesions in the mouth, eating can be painful. The cat will refuse to eat and therefore lose weight.

Anxiety and Stress

Cats suffering from anxiety and stress will eat less. Stress may be caused by changes, separation, jealousy or diseases.

Stress may be cured by offering more attention to your pet or in more serious cases, by administering tranquilizers and therapy.