I bet you were horrified when you saw your beloved horse eating horse poop. I know the feeling. I was shocked to see our beautiful healthy mare nibbling, no not nibbling...it was more like chowing down on a semi fresh pile!
You have to ask... why? There are a number of reasons why, but more importantly is how to stop it, which I discovered quite by accident. The means to stop your horse from eating poop will make a lot more sense when you understand why they are doing it in the first place.
Let's address them one by one. It is instinct for foals to eat manure to seed their gut with bacterial flora to aid in digestion. Horses aren't the only animals to do this. Baby rabbits do it too.
This is perfectly normal and healthy behavior and is short lived. In this case there is nothing to do about it, but let the foal do what nature has intended. If your horse is an adult, give them a dose or two of a probiotic to replenish the good bacterial flora in the gut.
Even if your horse does not need any probiotics, it will not harm them to get it. It's akin to you eating yogurt. You can safely give them to your horse and thereby rule out gut bacteria as a reason for copraphagia.
It comes in a tube paste much like a horse wormer. Probiotics for horses are sold at feed stores and large animal vet clinics. The same probiotics that are used on cattle can be used for horses as well. Just add it to the grain.
Boredom. This is more often seen with horses that are stall bound and begin to develop vices. Much like a prisoner trapped in solitary confinement the horse will begin to go a little crazy. They try to cope with the stress by developing odd behaviors: cribbing, weaving or eating their own horse poop.
In the case of boredom...for heaven sake get that horse out of the stall. Find a pasture with pasture mates and do your best to find more time to ride with plenty of variety.
Nutritional deficiency. A horse that is lacking in a needed nutrient or mineral may eat horse poop in an effort to replenish the missing nutrient. Make sure that you horse has a balanced diet.
Do they have a mineralized free choice salt block? If they are on grass hay are they getting enough grain in their diet for calcium? Is your horse getting enough food to eat? Are they a healthy weight?
Now I know what you are thinking, "My horse is not in a stall, I have already given probiotics, my horse has a perfectly balanced diet, if anything she's overweight and still she eats her own horse poop!"
Let me tell you my story. The above paragraph describes our mare to a tee. I gave probiotics at our veterinarians suggestion. I wormed her. She was up to date on all vaccines. She was/is on a very balanced diet, is ridden regularly and lives in a small tight knit herd of horses with plenty of room to play and socialize. Yet...she continued to eat horse poop.
Why? I was stumped. My friend suggested that she was simply hungry. I laughed. Not this horse. If anything she was overweight. Then it happened.
We had a terrible unusually frigid cold snap in the dead of winter. Immediately I increased the amount of hay the horses were getting. It was so cold I knew they needed those extra calories to keep warm. I was feeding them so much hay that they were not cleaning it all up between meals.
Normally I would not do that, as our little poop eating mare is also a VERY easy keeper. I really have to keep an eye on her to prevent obesity. She is always in the stalls rummaging around and pulling up the heavy rubber mats looking for leftovers.
This cold snap lasted for several weeks. So for several weeks my little fatty had plenty of roughage to rummage through between meals. It was then that I noticed that nasty little horse poop eating habit of hers had completely stopped!
So had my friend been right all along? Was it simply because she was hungry? How could she be hungry when she was clearly getting plenty of calories and then some? Then it hit me.
She wasn't hungry, but she did have a stomach ache because she had an empty stomach. Let me explain. Horses have very small stomachs. They are grazers that are meant to eat tiny amounts of food ALL DAY LONG. Nature made them that way.
When a horse has an empty stomach they produce stomach acid and that in turn produces stress. In order to reduce the acid and relieve the stress our poor little mare was reduced to eating her own horse poop to fill the void. She didn't need more calories, but she did need something in her empty stomach!
Most horse owners feed their horses twice a day because that is what is most convenient for us. The horses would be happier if they received 4 or 5 small meals instead. But that is not very practical.
The solution? Offer free choice grass hay if you can. At first a piggish horse will over eat. Once they realize the food will always be available, they calm down and self regulate just like the wild horses do.
If given the choice between horse poop or hay, I'm pretty sure your horse will choose the hay.