Abnormal Weight Loss in Dogs

My dog is losing weight and I don't understand why?

Weight loss in dogs may be associated with many normal and abnormal conditions.

"Weight loss is considered to be clinically significant when it exceeds 10% of the normal body weight."

Weight loss is considered to be clinically significant when it exceeds 10% of the normal body weight and when it is not associated with fluid loss or dehydration. For example, a healthy Golden Retriever weighing a breed-normal seventy pounds would have to lose over seven pounds before the weight loss would be considered clinically significant. Changes in diet, environment, or stress levels, including the addition of new pets, may lead to weight loss that is rarely permanent or significant.


What has caused my dog to lose weight?

Weight loss is the result of insufficient caloric intake relative to the body's requirement. This may be caused by:

  • high energy demand associated with excessive physical activity or prolonged exposure to a cold environment.
  • a hypermetabolic state during which, the body burns calories at a faster rate due to an underlying illness.
  • inadequate or poor-quality diet.
  • insufficient quantity of food intake associated with anorexia (lack of appetite), swallowing disorders, or regurgitation.
  • malabsorption and/or maldigestion disorders (a decreased ability to digest and/or absorb nutrients from food).
  • excessive loss of nutrients or fluid from vomiting, diarrhea, or excessive urination.


What other signs should I look for?

Weight loss can be caused by disorders in many of the body's organ systems, and can affect any or all organs. Questions that may provide insight into the cause of your dog's weight loss include:

  • Is your dog's appetite normal, increased, or decreased?
  • What kind, when, where, and how much dog food are you feeding your dog?
  • How and where do you store your dog food?
  • Does your dog have any trouble swallowing?
  • Have you observed any regurgitation or vomiting, diarrhea, loose stools, or changes in water consumption or urination?
  • What color and consistency are your dog's stools?
  • Is there a change in volume or frequency of stools?
  • Has your dog been spayed or neutered?
  • Does your dog have a fever?
  • How often do you administer your dog's heartworm preventive? What type of preventative do you use?
  • Is your dog on any other medications or supplements?


How can the cause of my dog's weight loss be diagnosed?

A thorough medical history and physical examination will help your veterinarian determine the most useful diagnostic tests to perform. Blood and urine tests and radiographs (X-rays) are the most commonly recommended diagnostic tests. Abdominal ultrasound may also be recommended.


What are some of the common diseases that cause weight loss?

Many diseases can cause weight loss. In fact, most chronic diseases will result in weight loss at some time during the course of the disease. However, some of the more common conditions associated with weight loss include:

  • anorexia (lack of appetite) due to a behavioral condition or disease.
  • pseudoanorexia caused by loss of smell, inability to grasp or chew food, swallowing disorders, vomiting, or or regurgitation.
  • malabsorptive disorders that inhibit the body's ability to absorb nutrients from the intestinal tract such as infiltrative and inflammatory bowel disease, lymphangiectasia, or severe intestinal parasitism.
  • maldigestion disorders such as exocrine pancreatic insufficiency, that interfere with the body's ability to break down food into usable nutrients.
  • metabolic disorders such as diabetes mellitus, hypoadrenocorticism (Addison's disease), hyperthyroidism (rare in dogs), and cancer.
  • diseases involving the major organs (heart, liver, or kidneys).
  • neuromuscular disease resulting in weakness or paralysis.
  • swallowing disorders.
  • central nervous system disease causing depression, anorexia, or pseudoanorexia.
  • increased caloric demand associated with excessive physical activity, prolonged exposure to cold, hyperthyroidism, pregnancy or lactation, fever, infection, inflammation, and cancer.


What can be done to treat my dog's weight loss?

Treatment will be determined by the specific cause of your dog's weight loss. Once a specific diagnosis is made, treatment to resolve the problem or improve your dog's quality of life will be immediately initiated.


What is the prognosis for my dog's weight loss?

The prognosis ranges from excellent to grave, depending on your dog's specific diagnosis. A thorough medical history, complete physical examination and appropriate diagnostic testing will assist your veterinarian in determining both the prognosis and the best course of treatment for your pet.
