There are many causes of diarrhea in dogs. The most common are intestinal parasites (e.g., roundworms, hookworms, Giardia), bacterial infections or overgrowth, dietary indiscretion (e.g., garbage ingestion or an abrupt diet change), and inflammatory diseases (e.g., diet intolerances or allergies). Many of these diseases are easily diagnosed and cured with proper treatment. However, some disorders are not curable and must be managed with medication and/or dietary modification.
Diet plays a large role in the management of most cases of chronic diarrhea in dogs. For example, symptoms of food intolerance or allergy may completely resolve with a hypoallergenic or novel protein diet. Dogs with exocrine pancreatic insufficiency (caused by a lack of digestive enzymes produced by the pancreas) should eat an easily-digestible diet that is either very low fat or sometimes high in fat, depending on the animal’s response. Inflammatory Bowel Disease (IBD) is a disorder of unknown cause that is characterized by inflammation in the digestive tract. Some dogs with IBD benefit from hypoallergenic diets due to an underlying allergy.
Sometimes the diet is not the primary cause of digestive tract dysfunction, but when diarrhea occurs over a prolonged period of time, it can lead to nutrient deficiencies or exacerbate the underlying disorder. Most dogs with chronic diarrhea benefit from switching to a diet that can improve their ability to digest and absorb nutrients, thereby optimizing the overall health of the animal.
Characteristics of a diet that may improve digestive tract health include:
- Good quality protein that has high digestibility (exceeding 85%), which requires less gastric, pancreatic, biliary and intestinal secretions for more complete digestion and absorption. Protein loss through the gut is common with chronic diarrhea. An easily-digestible diet is recommended because the lining of the intestines is often damaged and this can impair digestion and absorption.
- Fat is a tricky nutrient. It is a good source of energy, so a high fat diet is beneficial in some diseases. However, other conditions result in altered fat transport or metabolism, so a low fat diet is better. It may be necessary to try different diets to see which one works best.
- Both soluble and insoluble fiber have beneficial effects, so a diet with moderate fermentation and solubility is recommended to get the benefit of both types.
- Carbohydrates should also be highly digestible. White rice is considered to be the best source of carbs for digestive tract disorders.
Other ingredients that may be important to digestive health are:
- Glutamine — a non-essential amino acid that has many supportive functions for the digestive tract. Supplementation can improve digestive health and optimize immune system function.
- Prebiotics — dietary substances that help beneficial bacteria in the gut and deter harmful bacteria. These are often found in commercially-prepared diets for digestive tract health.
- Probiotics — live microorganisms that are added to the diet to improve the balance of bacteria in the gut.
The diet must also be palatable so the dog will want to eat it, and nutritionally balanced so the dog does not suffer from nutritional deficiencies or excesses.
While it is possible to prepare a homemade diet to meet these recommendations, I recommend you consult a veterinary nutritionist for help in formulating an appropriate recipe. Alternatively, many prescription and even a few over the counter diets are available that meet these criteria and have been used successfully for years. Ask your veterinarian for a recommendation appropriate to the particulars of your dog’s situation.
Dr. Jennifer Coates