The Digestive Tract
From the mouth to the bowel, a healthy digestive tract is the foundation of health. The "best" diet is only as good as what the dog can digest well so that nutrients are absorbed. In some cases, the digestive tract is compromised by disease, quality of foods and supplements, or genetic predisposition. The good news is that most dogs benefit and respond well to a dietary approach that considers individual needs.
Allergy or Intolerance?
A food allergy is an immune system response to an otherwise harmless food. Antibodies identify the food every time it's consumed. Histamine and chemicals are released. Allery can be the cause of excessive scratching, chewing paws, yeast overgrowth, skin eruptions, sloppy stool and other symptoms.
A food intolerance is a physiological response that does not affect the immune system and may not have any apparent reason. While diagnosing the difference between allergy and intolerance has clinical relevance, relief is the goal!
Finding The Problem
Things are not always as they seem. Parasites can cause gastrointestinal problems. Some parasites shed in cycles so that one fecal check may be perfectly clear while another, just 1-2 weeks later may show something quite different. To make this a little more challenging, other diseases can manifest as gastrointestinal problems and bacterial overgrowths are not as uncommon as you may have heard. As always, your first stop, and perhaps second and third, should be to visit your vet. Once the more serious issues been ruled out, there are steps you can take to make life better for your dog.
What You Can Do
Your first step is to make a diet change. Use one novel protein and one novel carbohydrate (grain or vegetable) for 8 weeks. These must be foods that your dog has never eaten before - not even one bite. Nothing else is fed during this time. No supplements and no treats that contain anything other than the two new foods.
Acidophilus helps to strengthen the digestive tract by adding "good-guy" bacteria to the existing, healthy bacteria population in the dog's gut. B-Complex vitamins play important roles for most body functions, including cells in the digestive tract and are helpful in improving appetite. Be sure that the diet provides enough zinc because zinc responsive diarrhea can be associated with a poor diet.
Tannins (found in Antioxidant Booster) helps some cases of diarrhea. Digestive Enzymes or Plant Digestive Enzymes can benefit some dogs and may be a good adjunct to the correct diet. Remember that "correct" needs to be based on what a dog tolerates rather than on a certain belief system of what the dog "should" tolerate.
L-Glutamine is a supplement that can help to rebuild healthy tissues in the digestive tract and some dogs benefit from it immensely.
For Further Reading
Optimal Nutrition: This book provides extended discussion, explanations and walks the reader through diet plans.
The Allergy Problem: Solutions for dogs that suffer from food-related allergies.
Acidophilus Treatments for Persistent Diarrhea by Dr. D Gaon - Acidophilus can help control problem diarrhea
The Probiotic E. faecium Causes Problems by Dr. W Vahjen et al Not all probiotics help. In fact, E. faecium (found in several probiotics) increases salmonella and campylobacter in healthy dogs
Bacteria in the Gut by Dr. RA Rastall Acidophilus probiotics improve immune function
Diagnosis of Infectious Diarrhea in Dogs and Cats by Stanley Marks- A review of three bacteria that cause infectious diarrhea