Housebroken Horses and Flying Asses

How did we end up here? Discussing the elimination habits of herbivores vs carnivores/omnivores?
We're dog trainers, thats how, and things quickly slipped out of control and down into a rabbit hole. And even though my conversation with Maggie, a wonderful dog trainer that I am desperately trying to lure back into town so that we can team up and conquer the world, quickly got mired in the weeds of insanity (as they so often do), there is a kernel of relevance to where we ended up - hunkered down with our rabbit.
How we got to donkeys living in the house is mostly irrelevant, but that's where we landed. And that was when we began tracking the path of trainability of members of the equid family vs that of farm animals such as goats and sheep, and the behaviors that we can expect because they are biologically present to begin with.
I made, as I often do, a blanket statement based on a hunch and nothing more, that horses and other herbivores would be nearly impossible to house train.
Did you see a rabbit run past? Lets follow it!

First, the question arises, can we train horses and other farm animals to defecate outside?
Most any behavior within an animal's behavioral capability is trainable (this is important, we'll revisit this deeper in the hole). Certain species are, of course more intrinsically trainable than others. Horses have been domesticated for between 5 and 7 thousand years, and were trained for much of that time (Dogs, current thinking believes have been domesticated roughly twice as long). Domestication is the act of choosing animals that better fit our needs, and trainability, to some extent is part of the overall picture.
Horses and dogs are not the same, however. Their evolutionary histories are completely unrelated. Horses form hierarchies led by a mare and a stallion, the mare leads and the stallion drives and protects. Cooperation is not necessary for survival (grass being relatively easy to acquire), whereas in wolves, cooperation is absolutely imperative to survival.
This is just one example of the vast behavioral toolkit that moves have that horses and herbivores do not. Food sharing is necessary in wolves. It is nonexistent in horses. Patience and delayed gratification are imperative in animals that must hunt for a living and absent or nearly so in herbivores. The innate biological animal that was the wolf, and is now the dog is the reason that dogs are far easier to train than are horses. Horses are still very much flight or fight animals, and trust is not a given. Every foal is born willing to flee our touch and must be tamed anew, unlike puppies who will scamper up to most humans from the moment scampering is possible.

In spite of all of these challenges,we have worked for thousands of years to make the horse (and donkeys) biddable and willing to acquiesce to our training and handling. Horses can be trained to do an astonishing number of intricate and complex behaviors with only the slightest of work on the part of the rider.
Food animals (cows, sheep, goats, etc...) do not have this carefully selected history. These animals have been bred for docility and food production, fecundity, and the lack of intellectual curiosity necessary to live in a barn all day without tearing down the walls (one of the by products of domestication is smaller brain size).

So, if we are to tackle the idea of bringing Maggie's racing donkey (or a cute fuzzy goat) into the house to housebreak it, we must keep all of this in mind.
But, how trainable an animal is isn't the end of the story. The carnivores and omnivores that we have domesticated and brought indoors (cats and dogs) come from wild ancestors that live in dens. Many animals that live in dens have a natural - inborn inclination to not defile their living area with feces and urine. Cats bury their elimination, dogs make a production out of where and when they should eliminate.
The herbivores that we are discussing do none of these things. Horses defecate where they stand (there is a small caveat to this and we will revisit it later), and are so unconcerned about the act that they will do so while moving. Sheep, cattle, goats, and horses will all eat and defecate at the same time, something that a cat or dog will not do.
So, to house break a sheep or goat, not only must you overcome the large uphill battle of simple trainability, but you must also teach it to be aware that it is defecating. Think of that. You would have to take a biological action that the animal is likely barely aware of in the first place, show it that it is doing it, and then teach it to do it only in a certain place.
