Causes of Rapid Weight Loss in Older Cats

A lack of appetite can indicate serious issues for your kitty.
i white angora cat eating from food bowl image by Stephen Orsillo from

As your kitty ages she can develop a variety of health issues, some of which can cause rapid weight loss. Rapid weight loss can lead to other, potentially fatal conditions, so it's important you bring your furbaby in for a check with her veterinarian for a proper diagnosis and treatment.

Dental Disease

Over time, plaque and tartar accumulate on your kitty's teeth. Without regular veterinary dental cleanings, this buildup can lead to the inflammation and infection of your cat's gums. This causes pain in your cat's mouth, which discourages her from eating. While this, in itself, can cause weight loss, when a cat doesn't eat for a prolonged period of time -- around two weeks -- a condition called hepatic lipidosis develops, according to the Animal Health Care Center of Hershey. This condition results from the buildup of fat in the cat's liver, leading to more serious symptoms like rapid weight loss, which can be fatal. Both the dental disease and the hepatic lipidosis require treatment by a veterinarian to prevent continuing problems with eating and weight loss.

Kidney Disease

One of the most common issues that older cats experience is the degradation of their kidney function, leading to kidney failure, according to the Cornell University College of Veterinary Medicine. Symptoms of kidney disease include rapid weight loss, a decrease in appetite, lethargy and trouble urinating. Because the kidneys filter toxins out of the body, when they don't function properly, these toxins build up in the cat's body, leading to death. To treat kidney disease in senior kitties, change to a prescription food lower in protein, sodium and phosphorus to put less stress on their kidneys, the American Society for the Prevention of Cruelty to Animals advises. Your vet may recommend other medications and special care like subcutaneous fluids.


Another disease common in cats older than 10 years old is hyperthyroidism. This disease results from an overproduction of the hormone that controls your cat's metabolism. This hormone, thyroxine, is produced by the thyroid gland. Excess amounts of thyroxine increases the cat's metabolism, resulting in hyperactivity and the rapid processing of the foods she ingests. Even though your cat eats normally, the calories burn at a faster rate, which leads to rapid weight loss. Her appetite may increase even as she continues to lose weight. Other health conditions such as high blood pressure and kidney problems can accompany hyperthyroidism, also resulting in weight loss. Surgery, medication or radio-iodine therapy are used to treat hyperthyroidism; consult your veterinarian to see which treatment might work for your cat.


Many forms of cancer affect older cats resulting in weight loss. Cancers that affect your cat's internal organs can lead to gastrointestinal issues that result in vomiting, loss of appetite or diarrhea, according to VetInfo. There are many forms of cancer that your senior kitty can suffer from, including cancerous tumors or skin cancers. This condition can spread rapidly and needs immediate care. Cancer causes death in half of pets older than 10 years old, according to "The Older Cat: Recognizing Decline & Extending Life." Surgery, chemotherapy or radiation therapy can treat cancer in older cats.


Older cats, especially obese older kitties, can develop type 2 diabetes, a condition that can lead to rapid weight loss. Diabetes results when your cat's body fails to respond to the hormone insulin, produced by the pancreas, or the pancreas doesn't produce enough of it, according to WebMD. This hormone is involved in the metabolizing of glucose in the body to produce energy. Without it, your cat's blood sugar rises, sometimes to dangerous levels. This can temporarily increase your kitty's appetite as her body tries to get the glucose it needs by prompting her to ingest more food. Because she can't properly metabolize the food, this will result in weight loss. Your cat will eventually lose her appetite, drink an increased amount of water and become lethargic. Cats with diabetes may require medication, dietary changes or insulin injections.


Elderly felines have reduced mobility due to arthritis, dementia and a variety of other conditions. Place your kitty's food and water dishes within close proximity to her favorite resting spot so she can easily access them. Some older cats fail to eat when they can't get to their food, leading to hepatic lipidosis and weight loss. To tempt your older kitty to eat, feed her soft canned cat food. Softer foods are easier for cats with dental problems to eat. Heat the food in the microwave for a few seconds to enhance its aroma, making it more appetizing.

Some older cats have a reduced sense of smell, which can cause them to stop eating; heating the food helps your kitty smell it and may tempt her to eat it. Always consult with your veterinarian at the first signs of weight loss in your elderly cat.

Always check with your veterinarian before changing your pet’s diet, medication, or physical activity routines. This information is not a substitute for a vet’s opinion.

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