Weight Loss in Dogs
Weight loss in dogs can be the result of a lot of possible health problems, from worm infestations to organ failure. This page looks at the possible causes dog weight loss.

A dog losing weight, either suddenly or over a period of time, is a sign indicating that there is some underlying health problem.

Significant weight loss of over 10 percent of the normal body weight is considered serious enough for veterinary intervention.

Weight loss in dogs usually occurs when the dog’s body loses nutrients faster than it can consume them due to some physical health problems, which may or may not be caused by a loss of appetite.

If your dog seems to be losing weight, measure his weight daily and keep a record of his weight over a period of one week or so.

In the meantime, observe your dog and watch out for other possible illness symptoms, in particular:

  • Chronic vomiting
  • Chronic diarrhea
  • Appetite loss
  • Difficult swallowing
  • Regurgitation
  • Stool eating
  • Weakness and lethargy

Make a note of any symptoms that accompany the weight loss – this will be very helpful for the vet in making a diagnosis.

There are many health problems that can cause a dog to lose weight. Below is a list of some possible causes.

Weight Loss in Dogs – Problems with Digestive System

Very often, dog weight loss is caused by a problem in the gastrointestinal tract, in which case, the weight loss is often accompanied by diarrhea or vomiting. For example:

Inflammatory Bowel Disease

In serious cases of IBD where the upper GI tract is inflamed, the dog will have diarrhea and vomiting, as well as weight loss.


Gastritis is the irritation and inflammation or infection of the stomach lining. Chronic gastritis causes chronic vomiting and appetite loss, which results in weight loss.

Stomach Ulcers

Dogs suffering from stomach ulcers also have chronic vomiting, sometimes even with an empty stomach. Ulcers lead to appetite loss as well as weight loss in dogs.

Gastric Outflow Obstruction

This is a condition in which the stomach contents cannot be emptied due to such problems as chronic gastritis, gastric tumors, or foreign bodies in the GI tract.

Dogs with a complete obstruction usually vomit immediately after eating, and will suffer from appetite loss, bloating, belching, and weight loss.

Problems with the Esophagus

Problems with the esophagus (e.g. mega-esophagus, esophageal blockage by foreign body, esophageal tumors) lead to difficulty eating and subsequent appetite and weight loss.

Intestinal Parasites

: Intestinal parasites such as hookworms, roundwormswhipworms, and giardia can also cause weight loss in dogs.

These parasites are most common in puppies and younger adults or in those boarded in crowded kennels.

Infectious Diseases Causing Weight Loss in Dogs

Infections caused by different microorganisms such as bacteria, fungi, and viruses can wreak havoc in a dog’s body and immune system.

Some examples of infectious diseases that cause dog weight loss include Lyme disease, blastomycosis, and valley fever.

Hormonal Disorders Causing Weight Loss in Dogs

Weight loss can be a symptom of some hormonal disorders, such as:

Diabetes mellitus

Diabetes mellitus, or sugar diabetes, is a result of insufficient production of insulin by the pancreas. The symptoms of early stages in diabetes include drinking a lot of water and frequent urination, appetite gain but weight loss.

Addison’s disease

Addison’s disease is characterized by an insufficient production of corticosteroids and mineralocorticoids, which regulate important body functions.

Dogs suffering from this disease have intermittent vomiting and diarrhea and gradual weight loss. They are lethargic and have weak muscles and slow pulse.


This hormonal disease is the opposite of hypothyroidism. Hyperthyroidism is characterized by increased metabolism as a result of an over-production of the thyroid hormones.

Because of increased metabolism, dogs with hyperthyroidism lose weight over time. Fortunately, hyperthyroidism is rare in dogs.

Other Problems Causing Weight Loss in Dogs

Sometimes, a dog losing weight is as a result of an organ failure, such as kidney failureliver failure, and heart failure.

Other problems that can lead to dog weight loss include situations in which excessive energy (calories) is needed for the body, either to fight a chronic disease such as cancer, or some form of inflammation or infection, or to perform demanding physical activities.

Dog Losing Weight – What To Do?

As you can see, there are a lot of possible causes of dog weight loss. If your dog is losing weight and/or is not eating, a thorough medical check-up is necessary to find out the underlying cause.

Treatment involves identifying and dealing with the underlying cause.

In the meantime, you can do your dog a great service if you switch his diet to a natural, high-quality diet if you have not already done so.

Adding supplements and vitamins to the diet helps significantly.

Digestive enzymes can be given to help the dog with better food digestion and nutrient absorption. Multiple vitamins should also be given especially if your dog is on a commercial dry food diet (kibbles). Probiotics can strengthen the digestive health and immune system of a dog.

If your dog is not eating, try to warm his food to bring out the aroma or trying adding spices such as peppermint, fennel, ginger, alfalfa, and dill to his food.