When your dog starts to eat his own stool, the cause may not always be obvious. While it may be a deficiency in his food--consult your vet to find out whether your dog is getting enough B vitamins in his diet and whether he might be getting too many carbohydrates--the problem is more likely to be behavioral. Your dog may be responding to anxiety, boredom or other stress, and he may well have learned the behavior from watching other animals.
Instructions
Pick up any pet feces in your yard regularly. If feces isn't available, your dog cannot eat it.
Feed your dog the same amount of the same food, but in smaller, more frequent portions spaced throughout the day. This helps eliminate the feces-eating urge in some dogs.
Keep your dog active by providing lots of exercise and consider making toys available to help keep her entertained. Some dogs eat stool as a negative behavior associated with boredom or anxiety; keeping your dog well-entertained can ease all of these stressors.
While walking, keep your dog on a leash. Correct him with a firm "no" if you see him approaching animal feces or his own leavings. You can also take him into the yard for his own potty breaks while still on the leash and, as before, correct him with a firm "no" if he shows any interest in his own leavings or any other stool that might be present.
Use a commercial product, such as Dis-Taste or For-Bid, to make the feces unpalatable to the dog. These products should be fed to the animal that produces the feces. If the dog is eating her own stool you'd feed her the product, or if she's eating stool produced by another pet you'd feed the product to that other pet.