Depending on the reason for your cat’s weight loss, you may notice that your cat’s appetite is reduced or entirely gone, a condition known as anorexia. This is dangerous for cats, because they are prone to something called hepatic lipidosis, or fatty liver syndrome, a life-threatening condition that can develop when the liver must process large amounts of stored fat to provide energy to the body.
But there are other medical situations that will cause your cat to lose weight, even if they continue to eat their normal amount of food.
Whether your cat is eating or not, if you notice your cat is losing weight, it is important to consult your veterinarian. If you are not sure what your cat’s ideal weight should be, your veterinarian will be able to provide guidance and a suggested feeding regimen to meet your cat’s nutritional needs.
Causes of Cat Weight Loss
Anxiety, stress, or depression. Cats under psychological stress may go off their food, which can result in weight loss. Situations that may upset your cat include excessive noise, other animals in the feeding area, dirty food dishes, or proximity of the food dish to the litter box. Cats can also be upset by the disappearance of another pet or by a change in a routine.
Cancer. Although not all cat weight loss is caused by cancer, it is a relatively common culprit. Other symptoms that commonly appear include loss of appetite, lethargy, and hiding.
Diabetes. This disease, which may be caused by a failure to produce the hormone insulin or an impaired ability to respond to it, commonly causes weight loss in cats, often with a change in appetite. Cats with diabetes may also drink excessive amounts of water, urinate more than usual, act sluggish, develop urinary tract infections, and have sweetly scented breath.
Feline infectious peritonitis. This virus, which most commonly occurs in cats raised in catteries, is known to cause wasting. Cats with FIP will seem sick, often with a fever that doesn’t respond to antibiotics.
Gastrointestinal problems. There are a variety of different conditions in the gastrointestinal tract that may cause cat weight loss. When this is the case, other symptoms may include diarrhea, lack of appetite, and vomiting. Common GI problems that produce weight loss in cats include inflammatory bowel disease, food allergies, or certain infections.
Intestinal parasites. Also known as worms, intestinal parasites may be the cause of your cat’s unintentional weight loss. Although symptoms are not always present, these parasites also may cause diarrhea, bloating, vomiting, and trouble breathing.
Organ failure. Many elderly cats exhibit weight loss, and it can be difficult to determine the precise cause of the problem, especially because metabolism changes with age. Conditions such as kidney disease become more common as cats get older. Your veterinarian can identify these problems with simple blood and urine tests.
Hyperthyroidism. Your cat may have a good appetite; in fact, they may be eating more than usual but is still losing weight. Hyperthyroidism results from a benign hormone-producing tumor on the thyroid gland that elevates levels of thyroid hormone. In addition to weight loss, hyperthyroidism may cause increased drinking and urination, increased activity, vomiting, diarrhea, and muscle wasting. In later stages, it may even lead to heart problems or death. Older cats also are particularly prone to developing this condition.
Toothache. If your cat suddenly stops eating and begins to lose weight, but seems otherwise healthy, it could be something as simple as a sore tooth causing the problem. Drooling and pawing at the mouth may be other signs of a tooth issue. Mouth ulcers or severe gingivitis can also contribute to the problem.
Treatment and Home Care for Underweight Cats
To determine what is causing your cat’s weight loss and design the best treatment plan for you and your pet, your veterinarian will likely do a complete physical exam, blood work, and urinalysis.
Depending on the reason for your cat’s weight loss, a variety of treatments and dietary changes to treat the underlying condition and restore weight may be prescribed. Fortunately, even in older cats, weight loss can often be treated, if not cured.
The weight loss caused by certain conditions of the gastrointestinal tract may be addressed, either solely or in part, by making appropriate changes to your cat’s diet. If your cat is suffering from inflammatory bowel disease or other conditions that make food absorption difficult, an easily digested diet may be recommended. Cats that lose weight because of food allergies may recover completely when the offending foods are removed from their diet.
In situations where lack of appetite is contributing to weight loss, appetite-stimulating medications or feeding tubes may be used to maintain adequate nutrition while the cause of anorexia is being addressed.