How to desensitize a horse to Cows??

I think your best bet is to borrow a cow or two! Turn them in the field at your yard and gradually introduce your horse to them.

Failing that, turn his head away from the cows when you see them, shoulder in or leg yield past them a few times. Get off and lead him if this will help. Praise him when he's good and reassure him when he's frightened. Don't be too soft with him though, he needs to learn that its not acceptable to bolt at anything. For example, I had a horse a while ago who was terrified of going in the trailer after a bad experience. I spent hours stood with him, he learnt that to go backwards or sideways was wrong and got him into trouble. He also knew that he could stand still for as long as he wanted, and that going forwards was good, just so long as he wasn't evasive (backwards/sideways).

Take trail rides often near the cows with the other horses that are used to them. Get off your horse before you reach them, as the your horse will probably think that he'll have more time to get away as the cows will eat your first. Talk nicely to your horse. Maybe if you can even show your horse that the cow is fine by petting the cow. If it comes to this distract your horse with a treat.

The fact that he has this habit, and that you know it and are anticipating it, is probably telegraphed to him each time that you approach any cows. So, when you are desensitizing him (go back and forth, back and forth, exposing both sides of him to the cows), remember to keep yourself as relaxed as possible so that he picks up your confidence at the same time. I like the idea of talk to a neighbor that may have cows and see if they would allow you to put all of the horses in a safe corral next to their cows for a couple of hrs a day so that they can get used to the sight, movements and smell of the cows. Our horses grew up used to cows, but pigs was their nemesis.

P.S. One other thing that you can do is to just have someone with a good, stout horse pony you by them so that he isn't able to bolt, that he has to just stay side by side and walk quietly and get over it that way. You may just have to try all of these methods before you find the one that works for this particular horse.

Just make it a point to ALWAYS go by cows on trail rides, and make him get as close to them as you can. Eventually he will get over it. Or, If you could get him into a pen next to cattle, that might help. Don't put your horse in a pasture with cattle,even though it may be the quickest way, or if you do don't leave him unattended. I know that many people mix their horses and cattle successfully, but there is always the risk that your horse could get hurt, and for something so trivial it would be a shame to have a huge vet bill or have to euthanize your horse.

I have an Anglo-Arab that does this exact thing. Even when he hears a cow, he flips. What's helped him the most is being in a pasture with horses who don't care, or at least it seems like it. I'm not completely sure he'll ever get over it, he even freaks when he sees one of those bull heads people use to practice roping on. Best of luck to you!

Can you borrow a cow?