I might eat another horse’s manure.

This is a pretty gross topic, but it is one I contacted my veterinarian a year ago for a reason as to why my horse would be eating manure all of a sudden.  Now one year later, it happened again while riding Bailey, she stopped to smell Cheyenne’s fresh manure pile in the snow in front of us and started to eat it!  I am told not to worry by my veterinarian, and that it is not uncommon.  Really?  I know my dog enjoys a hot meal of horse manure when he gets the chance and I never was worried about him eating it, I just thought it was gross.

But there must be some logical explanation or not?

Last year when this happened I thought I might have a reasonable answer.  It was right after Cheyenne had split Bailey’s lip with a kick which resulted in Bailey was not eating properly.  Since she was not chewing correctly, her digestion was compromised, and she was seeking out digested manure for nutrition from Cheyenne’s manure.  That seemed to make sense to me, and I actually found that quite remarkable that an animal would figure that out, if she did indeed figure it out.  I was told by my vet not to worry about it either way, plus I was in the process of separating the horses permanently because of their fighting.  I did ask my vet if Bailey was getting nutrition from Cheyenne’s manure and if I separate her from the manure, would Bailey need anything to supplement her deficiency?  I was told no, and so I separated them and really didn’t think about it.  I never saw Bailey eat her own manure.  Now, a year later, Bailey does it again, but why this time?

When an animal eats manure, it is termed coprophagia, derived from the Greek “kopros” for feces and “phagein” for eat.  It is fairly common behavior in foals starting at about two to three weeks old. The foal knows that it needs to populate its digestive system with the bacteria from the mother’s manure and that will help the foal’s intestines break down its new diet which includes roughage.  Foals may also eat manure to take advantage of the rich source of B-vitamins and vitamin K that are found in manure.  Adult horses might be doing the same thing.

With adult horses, eating warm manure might appear like a mash or a comfort meal on a cold day.  Some have suggested that a horse will eat manure because he lacks fiber, protein, and energy in his diet, or certain minerals or salt, or it’s the high moisture content.  Some professionals believe it could be from being bored or kept in a stall too long, or stress.

All these suggested reasons appear to be not much more than theories.  There really aren’t any studies on this subject.  Since manure contains undigested fiber and grains, as well as moisture, it normally doesn’t pose a hazard to a horse’s health.  There really isn’t any harm in the horse eating manure other than the potential for consuming parasite larvae if the horse isn’t properly dewormed. Adult horses are less likely to participate in this act, but if they do, it is considered normal in small doses. Beyond that, in adult horses, there may be some underlying problems.  If you are concerned, keep a log every time you see the action done so you have information to provide to your veterinarian.  For me, it was a total of 2x, one last year and one this year.

This quiz below came from the Star milling Co. site prepared by Dr. Bray, a consulting nutritionist for the company.  Dr. Bray is a retired professor and associate chair of the Animal & Veterinary Sciences Department at California State Polytechnic University – Pomona. He received his Ph.D. in Animal Nutrition from the University of Maryland and conducted his Ph.D. research at USDA. 

Fact or Fiction Quiz

1. Foals are more likely to learn about food selection if they eat their mother’s feces.
2. Coprophagy may serve to “immunize” the newborn against parasites.
3. The mare’s feces contain a pheromone that encourages foal to eat feces.
4. Coprophagy may serve to strengthen the social bond of mother and foal.
5. Coprophagy in adult horses means that something is lacking in their diet.
6. Horses that eat feces receive many vitamins & minerals that may be lacking in the diet.
7. Feces from animals that eat plants for food contain many of the B vitamins.
8. Coprophagy will populate the foal’s gut with “good” bacteria.
9. Exercise reduces coprophagy.
10. Coprophagy is normal, but if practice frequently, the horse’s diet should be evaluated for deficiencies in protein, fiber, and other nutrients.
11. Adult horses in a research environment have eaten feces when dietary protein is deficient, but stopped when a protein supplement was fed and the deficiency corrected. 

How did you do?

1. False
2. False
3. False – There are pheromones associated with waste products but no evidence to support that it “encourages the foal to eat feces”.
4. False
5. False
6. False – While this is the case with rabbits, it is not the case with horses.
7. False
8. True – Foal’s exploration and muzzling of his/her environment will expose the foal in the beginning days of life to bacteria, including from waste products. The influence of type of bacteria has not been documented.
9. True
10. False – Coprophagy is not related to nutrient deficiencies. It is, however, more common with confined horses when compared to pasture horses.
11. False – For adult horses that appear obsessive with the behavior, the addition of fiber (not protein) by adding roughage’s to the diet appears to reduce the frequency of the behavior. Feeding a balanced formula high in soluble fiber (beet pulp & soy hulls) to complement the forage portion of the diet is one way to ensure adequate nutrients and fiber favorable to gut health are being supplied. Feeding a low calorie, no grain, high soluble fiber balanced formula, is one option to ensure that the daily diet is balanced.

Ingestion of fecal material frequently raises concerns with horse owners.  Coprophagy is a natural exploration by all equids and the primary benefit is inoculating the gut with bacteria that are necessary for hindgut digestion in the herbivore gut. The habit or practice is more likely behavioral and probably in domestic management is accentuated through boredom. There are biological mechanisms with all animals that tell us when we are hungry, thirsty, or a desire for a “taste for salt”. However a horse cannot process the thought,  …oh, I need a little more iron, or riboflavin, or copper and thus randomly start to seek out a food source that hopefully supplies that nutrient(s). For all practical purposes coprophagy has absolutely nothing to do with nutrition unless the horse is unhealthy and in very poor condition. During my early training in animal nutrition, I recall a professor rationalizing that since microorganisms produce B-vitamins and vitamin K in the gut, coprophagy is a method of retrieving those nutrients so that they will enter the small intestine for processing and absorption. That concept has not been demonstrated and one needs to understand that microorganism live through out the gut and in non–ruminants, such as the horse, there is a significant population of micros in the distal (end) section of the small intestine and there is an opportunity for absorption of those nutrients generated by the micros.

Since I know my horses aren’t bored, have 24 hour pasture access, have a complete nutritious and balanced diet, have plenty of water, have salt and mineral blocks, I guess it was just one of those moments Bailey couldn’t pass up.  Luckily I have peppermints to give her!