By Jennifer Copley (Last Updated 21 November 2011)
In some cases feline weight loss is desirable. Many overweight cats must be placed on special diets to reduce their likelihood of suffering obesity-related illnesses. However, weight loss in cats that are not on restricted diets may signify a medical problem, particularly when accompanied by symptoms such as:
- Breathing difficulties
- Difficulty swallowing
- Dull coat
- Increased thirst
- Persistent sores
- Ravenous appetite
Illnesses That Can Cause Weight Loss in Cats
Medical problems that may cause weight loss include:
- Cancer – Cancer can cause increased calorie burning, appetite loss, or tumours in the intestines. Additional cancer symptoms may include lethargy, difficulty breathing, and persistent sores.
- Chronic Renal Failure (CRF) – Also known as Chronic Kidney Disease (CKD) and Chronic Renal Insufficiency (CRI), kidney disease is a common problem afflicting older cats. Symptoms include increased thirst and urination.
- Conditions That Cause Nutrient Loss or Interfere with Digestion or Absorption – These include protein-losing enteropathy and nephropathy, haemorrhaging from the intestinal tract or skin, inflammatory bowel disease, irritable bowel syndrome, chronic infections, exocrine pancreatic insufficiency, and gall bladder disease.
- Dental Infections or Injuries – A sore tooth or mouth can cause a cat to stop eating.
- Diabetes – This is an increasingly common problem among cats that many experts attribute to cheap high-carbohydrate cat foods.
- Feline Infectious Peritonitis – Additional symptoms of this viral disease include a persistent fever and lethargy.
- Gastrointestinal Obstructions – Common obstructions include hairballs and swallowed objects.
- Heart Disease – Unexplained weight loss, lethargy, and difficulty breathing (wheezing, asthmatic sounds) are symptoms of heart failure in cats.
- Hyperthyroidism – This is a common disease among older cats. Primary symptoms are increased hunger, weight loss, and hyperactivity. Many experts have attributed the increased prevalence of hyperthyroidism in cats to feeding from pop-top cans and the poor quality fish used in some cat foods.
- Infections That Depress the Appetite – These include cat flu, feline leukemia, and a variety of other medical conditions.
- Intestinal Parasites – Common parasites afflicting cats include roundworms, tapeworms, hookworms, and heartworms.
- Neuromuscular Diseases – Disorders of the central nervous system may cause appetite loss or inability to eat if they physically interfere with picking food up or swallowing it.
- Symptoms That Burn Extra Calories – Fever and inflammation may cause rapid calorie burning.
Other Causes of Weight Loss in Cats
Weight loss doesn’t always indicate a serious medical problem. Other causes of weight loss include the following:
- Anxiety or Depression – Cats may lose their appetites due to major changes such as moving house or the arrival of a new pet, other pets bothering the cat while he tries to eat, or the loss of a beloved human or animal. In such cases, reducing the stressor whenever possible, spending more quality time with the cat, engaging in play therapy, using natural anxiety remedies, and offering healthy treats (assuming that the cat is not overweight) can be beneficial.
- Bad Location of Food Dishes – Cats may avoid food dishes that are placed in high-traffic areas of the home or near litter boxes. Also, if the dishes are located upstairs, an older or mobility-challenged cat may have difficulty getting to them.
- Dislike of the Food – Food that is spoiled, stale, cold, or served in dirty dishes will be unappealing. Cats may also go off a previously liked brand of food or be averse to a new brand. Cats hate change, so when introducing a new food, it should be mixed gradually with the old food, increasing the amount each day.
- Food Allergies – A food allergy or intolerance can interfere with digestion or absorption of food. Symptoms of food allergies may include itchy skin and digestive upsets such as vomiting or diarrhea. Cats may also develop an allergy to plastic food bowls that makes them reluctant to eat.
- Poor Quality Food – Many cheap cat foods and foods not formulated for cats (such as dog food or human food) will not meet a cat’s nutritional requirements even when he eats full meals. Also, good quality cat food may lose nutrients when stored for a long time.
- Starvation – Starvation may be caused by not being fed enough; lack of appetite; having other pets steal food from the cat’s dish; or a higher rate of calorie burning due to intense exercise, cold environments, pregnancy, or nursing (see How Much Food Do Cats Need? for information on calorie requirements at various life stages).
Treatment for Weight Loss in Cats
Treatment for unexplained weight loss will vary depending on the reason. After doing a series of diagnostic tests to determine the cause, a veterinarian may prescribe:
- Treatment of underlying illnesses
- Dietary changes (better quality food, more easily digested food, a hypo-allergenic diet, etc.)
- Vitamin and mineral supplements
- Appetite stimulants
- Syringe, tube, or intravenous feeding
- Stress-reduction measures
It’s important to take action immediately if a cat stops eating. Cats that go without food for a couple of days or eat very little food for a longer span of time can develop hepatic lipidosis (fatty liver disease), a very serious and frequently fatal condition. Overweight cats that suddenly stop eating are at greatest risk for this disease.
Although the cause of weight loss may simply be a problem with the cat food or bowl location, when in doubt, consult a veterinarian, particularly if there are additional symptoms.
See The Cat Food Page for information on high-quality diets and foods that should never be fed to cats and kittens.
This article is not intended as a substitute for veterinary care and consultation. Medical concerns should be referred to a qualified veterinarian.
- Bower, J., & Bower, C. (1998). The Cat Owner’s Problem Solver. Pleasantville, NY: Reader’s digest Association, Inc./Andromeda Oxford Limited.
- Brooks, W.C., Veterinary Information Network. (Reviewed 6 September 2007). “Anorexia.” VeterinaryPartner.com.
- Fairview Drive Pet Hospital. (2009). “Weight Loss in Cats.” FairviewPet.ca.
- Hines, R. (2009). “Heart Disease in Dogs and Cats.”
- Martinez, E.A. (Reviewer). (28 September 2009). “Weight Loss in Cats.” WebMD.com.
- Pierson, L.A. (July 2010). “Feeding Your Cat: Know the Basics of Feline Nutrition.” CatInfo.org.
- Spielman, B. (2010). “Weight Loss in Cats.” PetPlace.com.