Weight Loss in Cats

Feline Weight Loss

Overview of Feline Weight Loss

Weight loss is a physical condition that results from a cat’s negative caloric balance. This usually occurs when the cat’s body uses and/or excretes essential nutrients faster than it can consume them. Essentially more calories are being burned than are being taken in. Weight loss is considered clinically important when it exceeds 10 percent of the normal body weight and is not associated with fluid loss.

In Cats, during weight loss, the appetite may be normal, increased or decreased.

What to Watch For

  • Weight loss
  • Loss of body condition
  • Loss of muscle mass
  • Poor hair coat
  • Diarrhea
  • Vomiting
  • Regurgitation
  • Difficulty swallowing

Causes of Weight Loss in Cats

There are many reasons for loss of weight in cats. Some of these include:

  • Dietary causes
  • Lack of appetite (anorexia)
  • Disorders related to poor absorption of nutrients
  • Disorders related to poor digestion
  • Metabolic disorders
  • Excessive nutrient loss
  • Neuromuscular diseases
  • Excessive use of calories
  • Cancer
  • Heart disease

Diagnostic Tests for Weight Loss in Cats

Confirmation of weight loss is necessary. A review of the cats former body weight(s) is essential. Once weight loss has been documented, a thorough history and physical examination, in addition to appropriate diagnostic tests are indicated to determine a cause of the weight loss. Initial diagnostic tests may include:

Treatment of Weight Loss in Cats

Your veterinarian may make several recommendations for the treatment of weight loss prior to instituting a full diagnostic work up. Such treatment is usually administered on an outpatient basis.

  • Sufficient calories in the form of adequate amounts of an appropriate, high-quality diet
  • Force-feeding
  • Appetite stimulants
  • Supplementation with vitamins and minerals for severely malnourished patients
  • Parenteral (intravenous) nutrition for patients who cannot take food orally
  • Comfortable and stress-free environment, especially when eating
  • An appropriate exercise regime

Home Care

Administer prescribed diets and medications precisely as directed. Periodically, weigh and record your pet’s weight. Contact your veterinarian if there is any change in body weight.


In-depth Information on Weight Loss in Cats

Weight loss is a physical condition that results from a negative caloric balance, as when metabolic utilization and excretion of essential nutrients exceed the caloric intake. Weight loss is considered clinically important when it exceeds 10 percent of the normal body weight and is not associated with fluid loss. 

Weight loss can result from many different mechanisms that share the common feature of insufficient caloric intake or availability to meet metabolic needs. Causes vary markedly from intentional restriction of calories in order to reduce weight in an obese patient, to weight loss associated with life threatening illness.

Historical information is very important, especially regarding type of diet, duration and environment of storage of diet, the patient’s daily activity and, environment, the presence of pregnancy, appetite, signs of gastrointestinal disease (vomiting, diarrhea, regurgitation), or signs of any specific illness.

Causes of Weight Loss in Cats

There are several disorders or situations that need to be considered when evaluating cats for weight loss. These include:

Dietary Causes

  • Insufficient quantity of food – not enough calories
  • Poor or inadequate quality of food
  • Decreased palatability (taste) of food
  • Spoiled food
  • Prolonged storage of food with deterioration of nutrients


    This is often seen with many disorders and diseases in cats.

Malabsorptive Disorders (poor intestinal absorption)

  • Inflammatory bowel disease (IBD) is a microscopic accumulation of inflammatory cells into the intestinal wall. The cause is unknown, although it is thought to have an immune basis. Diarrhea and weight loss are commonly seen with the disorder.
  • Lymphangiectasia is a chronic protein-losing intestinal disorder that arises from congestion and dysfunction of lymph carrying structures in the intestines. It is an uncommon disease in the cat.
  • Intestinal parasitism is most common in younger animals or animals that are housed in crowded and/or unsanitary conditions. It may involve roundworms, hookworms, coccidiosis.
  • Chronic infections of the bowel may lead to malabsorption. Examples include fungal infections and bacterial overgrowth.
  • Infiltrative tumors of the intestine may affect the intake of calories.
  • Gastrointestinal obstructions can prevent adequate absorption of nutrients and result in nutrient loss from vomiting and diarrhea.
  • Surgical resection of large segments of bowel can greatly decrease the overall absorptive surface of the intestines.



Maldigestive Disorders (inadequate break down/processing of food)

  • Exocrine pancreatic insufficiency (EPI) is a condition where the pancreas does not produce sufficient enzymes to break down food. It is a rare disease in cats.
  • A lack of bile salts due to liver or gall bladder disease affects digestion and absorption.

Metabolic Disorders

  • Various forms of organ failure (e.g. heart, liver, kidney)
  • Diabetes mellitus or sugar diabetes, which decreases the ability of the body to use sugar or glucose in the diet
  • Hyperthyroidism, where increased metabolism occurs secondary to increased out put of thyroid hormone

Excessive Nutrient Loss

  • Protein losing enteropathy (PLE), a group of diseases characterized by excessive loss of proteins into the gastrointestinal tract
  • Protein losing nephropathies, which involve protein loss through the kidneys
  • Chronic hemorrhaging from the skin or intestinal tract, which results in loss of proteins
  • Extensive skin lesions or burns that ooze serum and increase the loss of protein from the body

    Neuromuscular Diseases

  • Primarily disorders of the central nervous system (brain and spinal cord) that render the animal unable to eat or cause them to loose their appetite
  • Paralysis of the esophagus
  • Neurologic disorders that affect the ability to pick up food or swallow food

    Excessive Use of Calories

  • Increased physical activity
  • Prolonged exposure to a cold environment
  • Pregnancy or lactation (nursing)
  • Fever or inflammation
  • Cancer

    Chronic Infections

  • Bacterial infections
  • Viral infections
  • Fungal infections
  • Mixed infections



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