What Causes Weight Loss in Dogs?

Weight loss occurs when your dog's body uses or expels more calories than he is eating or absorbing. Your dog may lose weight for any number of benign reasons: the stress of a new home or a new pet, or perhaps he just doesn't like his food. However, weight loss is considered to be a problem if it exceeds 10 percent of your dog's normal body weight. Clinically dangerous weight loss can occur if your dog's appetite is decreased, which is often one of the first indicators of illness.

Malabsorption Disorder

Malabsorption disorders are characterized by the disruption of the normal absorption of calories and nutrients. Your dog will begin to lose weight because these vital elements are not properly delivered to her body, but rather expelled through her feces.

Digestive Disorder

Disorders that interfere with proper digestion, like exocrine pancreatic insufficiency or chronic diarrhea, cause the rapid or improper movement of nutrients and/or feces through the gastrointestinal tract, resulting in weight loss.

Metabolic Disorder

Metabolic disorders such as Addison's disease, Cushing's disease and diabetes can cause weight loss in your dog if not properly managed.

Neuromuscular Disorder

Depending on the specific neuromuscular disorder, your dog may lose weight due to loss of muscle mass, the inability to exercise or difficulty swallowing or holding down food.

Cancer

Severe weight loss is common in dogs with cancer. Your veterinarian should be able to prescribe a specialized diet for your dog to help her maintain optimal weight during cancer treatment.

Heart Disease

Dogs with severe or unmanaged heart disease will experience loss of appetite and weight loss.

Internal Parasites

Internal parasites like intestinal worms, heart worms, giardia or coccidia will cause weight loss in your dog if left untreated. Yearly physicals and monthly preventatives will easily prevent these problems.