Types
Autocoprophagia
Autocoprophagia deals with an animal eating its own feces.
Interspecific Coprophagia
Interspecific coprophagia deals with an animal eating feces from another species (dog eating cat, deer, rabbit, etc feces).
Several behavioral explanations are:
Attention-seeking behavior: When the dog engages in coprophagia, their owner tends to reprimand them and, therefore, pay attention to the animal. This may be a sequel to a medical condition, which brought about the coprophagia initially and, now that the medical condition has cleared, the animal continues to engage in coprophagia in order to get attention from the owner. This is unlikely in well-treated animals, however, because they will likely get all the attention they need without having to draw negative attention to themselves.
Allelomimetic behavior: The dog observes the owner picking up the feces and learns from them to do so as well.
Learned behavior: The dog observes other dogs engaging in coprophagia and mimics their activity, thus "learning" it from other dogs within the household or those living nearby. This begs the question as to what started the first dog to engage in coprophagia.
Maternal behavior: A bitch with puppies will often engage in coprophagia, and this behavior is normal. There are many theories as to why the bitch does this, including keeping the den clean and preventing the scent of the feces from attracting predators.
Dominance behavior: There have been reports of a submissive dog consuming the feces of one or more dominant dogs in the same household. There are other examples in nature where the submissive members of a group participate in apparently bizarre behaviors.
Reinforcement: Something about eating the feces itself reinforces the behavior. Things such as taste may be a factor in this. It's simply appealing to the dog to eat the feces, so it does so. This is the likely mechanism in interspecific coprophagia such as eating cat feces.
Feeding behavior: Many people feed their dogs only once per day. Some postulate that dogs naturally want to have multiple meals throughout the day, hence they use coprophagia to supplement their feeding schedule and fulfil this need.
Some veterinarians recommend adding meat tenderizer to dog food, as this makes the feces taste excessively bad to dogs. Several companies produce food additives that can also be added to the animal's food to make feces taste bad. Often, these food additives will contain Capsicum Oleoresin which gives off a repugnant odor making the fecal matter undesirable to the dog.
Causes
Coprophagia may result due to various medical problems. Primary among them are exocrine pancreatic insufficiency, pancreatitis, intestinal infections, malabsorptive syndromes, and over-feeding (especially high fat content diets). However, with the majority of these conditions, many other signs beside the coprophagia will be prominent, particularly diarrhea. Coprophagia is usually only a small aspect of these medical conditions. There have been a variety of behavioral theories put forth as to why canines engage in coprophagia. It is important at this time to define different kinds of coprophagia.
Treatment Options
Here are some suggestions:
Meat tenderizer: Some people theorize that adding various enzymes to the diet of a coprophagic animal may help. The suspicion is that these enzymes break down more of the nutrients in a dog's diet so that it gets adequate nutrition and need not ingest its feces to get a proper influx of nutrients. There are some reports of this treatment working.
Scolding/Punishment: This is a common method of trying to have an animal stop a behavior. Barking is a good example- owners think if they scold their pet for barking, it will cease to bark. WRONG, Punishment almost never works as well as reinforcement, however, and should only be used as a last resort. This may actually lead to more coprophagia as the dog learns that it gets attention (being scolded) if it eats its feces.
Ignoring: This is often used by owners because they have figured out that their dogs may want attention from eating the feces, so they ignore the dog when it's engaging in coprophagia. This is likely better than scolding and punishment, but probably not as effective as reinforcing a good behavior (such as coming when called).
Pickup: This is a treatment strategy by preventing access to the feces by the animal. In extreme cases of coprophagia, a muzzle may have to be administered when the dog is let outside to prevent it from eating the feces. Usually simply picking up shortly after the dog and preventing the dog from eating feces during walks is sufficient. Often this may break the cycle of behavior as described above under scolding/punishment.
Other chemicals: There are no less than several dozen purported chemical treatments for coprophagia, including homeopathic remedies. Of course, only anecdotal information is available about these compounds.
Muzzle: If the dog engages in this behavior when unattended, or consumes the feces directly when it comes out, a muzzle may be a practical solution to the problem. If it is well tolerated and the dog does not have to have it on for extended periods of time, this may be one of the more practical ways to deal with a dog who is coprophagic and unsupervisable.
Wait: Anecdotally, this seems to be a behavior most often occurring in younger dogs. Many owners report that their dog eventually grows out of it. While not exactly treatment, it is possible that the dog will stop being coprophagic as it ages.
Positive Reinforcement: This is the process of reinforcing another behavior instead of the coprophagia. When the dog is about to begin eating feces, the owner can use any variety of commands. "leave it", "come", "sit", etc. can all be used. The idea here is to distract the dog long enough to allow the owner to pick the feces up and make the dog forget about the coprophagia behavior.
Combination: It is almost impossible to recommend a single best treatment for coprophagia for all dogs. Because the mechanism and reasons why dogs engage in this behavior are unknown, it is not known which behavior modification therapies will be most effective.
Health Implications
Most of the time, coprophagia is merely a habit which is disgusting to owners but causes no real problems for the dog who is eating it. There are some important exceptions to this, however. The most critical is the possibility of ingesting internal parasites. Usually this will happen if your dog eats the feces of unfamiliar, infested dogs or the feces of wild life (such as deer). If you keep your animals properly de-wormed, the dog eating the feces of these animals is usually not at risk for internal parasites. However, the possibility of picking up a parasite from a strange animal (especially wild life) is very real, and the dog should be prevented from eating such feces as much as possible.
In addition to internal parasites, organisms such as Toxoplasma gondii is transmitted in some cat feces. This can cause a dog a variety of problems, including CNS and muscle damage. Try to keep the dog away from cat feces as much as possible because of this.
It's also possible that the feces, if left to sit too long, can become infested with fly larvae, foreign bacteria, fungus, etc. It is best to make sure your dog avoids these sources of disease as much as possible. Be sure to keep your dog away from strange feces when on a walk and clean up any old feces in your yard as soon as possible.
Some important canine viral diseases can also be transmitted by the focal-oral route and infection could result from coprophagia of infected dogs' feces. Hepatitis and canine parvovirus are two important diseases which can be transmitted in this manner. Fortunately, vaccinated dogs are at little risk.
