Having a litter box that never needs to be scooped sounds like every cat owner's dream. But finding Fido with his mouth stuffed full of cat poop is every dog owner's nightmare. Coprophagia, or the deliberate ingestion of fecal matter, is a problem that almost every dog owner will face at some point, particularly if there are cats present in the household. There may be one reason for the behavior, or several, depending on each dog's individual circumstances.
One of the main reasons dogs eat fecal matter from the litter box is that it contains a fairly large amount of undigested protein. Humans and dogs are able to use carbohydrates as well as protein as a source of energy. Cats cannot use nutrients other than protein as a form of energy, and so their diet has to be very high in protein. To digest this protein, the cat must get 10 essential amino acids. If any of these acids are lacking, a portion of the protein will go undigested. Extra protein will also be present in feline fecal matter if the cat is consuming more protein than it expends in energy.
Dogs may find this extra protein appealing because they are not receiving enough protein in their own diets, or may simply view it as an extra "treat."
If you find your dog eating cat poop, he may be acting on instinct. Dogs, who are descended from wolves, are predisposed towards cleanliness. Wolves, as well as mother dogs, will eat the fecal matter of their young to keep the den clean. Your dog may be acting on the instinct to keep the house, or what he considers to be his den, clean. This behavior stems from the desire to keep den mates and weaker dogs safe. If fecal matter is left around in the wild, other animals may pick up on the scent and track down the den.
Your dog sees you pick up poop on a regular basis, be it her own or your cat's. Your dog may be acting in a mimicry of you. This behavior, known as allelomimetic behavior, is your dog trying to do the same things you do. This can be particularly true if you have trained your dog to see you as the "pack leader" of the household. Your canine sees you picking up fecal matter and is trying to perform the same duty to lessen the burden of the pack leader.
If dogs are not given a proper outlet for their energy, they may get into things that you would rather they leave alone. The garbage can is one example of this, and so is the litter box. When dogs are anxious or bored, they will instinctively chew on things. The texture of the cat poop may be appealing to them as an outlet to relieve tension, or it may be reminiscent in taste or texture to canine wet foods.
Dogs may also eat cat droppings if he feels that, in doing so, he will prevent himself or the cat from being scolded. Dogs who have been severely punished for having accidents inside of the house may, on occasion, eat their own feces as well as the cat's.
Physical and Medical Causes
A dog may eat cat poop as an indication of hunger. If your dog is not receiving enough food, she may resort to other outlets to get the nutrients he needs. This behavior can also be indicative of intestinal parasites, which sap the nutrients from your dog as she digests them, leading her to the litter box as an additional source of key nutrients.
Pica, a condition that is characterized by eating non-food items, is another medical cause that may drive Fifi to the litter box in search of a snack. Gorging, a condition in which the dog will eat more than is necessary, may be another cause.
Observe your dog when he goes to the litter box. Does he do it after meals, or if his food bowl is empty? Are there any other signs that something may be wrong? Does he only do it when you are out of the house? Make a list of times and circumstances under which the poop eating occurs. You may need to consult your veterinarian, dog trainer or canine behavior specialist to determine if a deeper medical or psychological problem is the root cause of the poop eating and will help you form a plan to prevent or eliminate this problematic behavior.