>>Where ever we put the hives, they would be near horse pasture

How near is near?

I was growing up on a farm with horses cows and bees, it never seemed to
be a problem.
Honeybees never bothered the animals.

Konrad

MY HIVES ARE RIGHT IN THE PASTURE .JUST SET THE HIVES SO THAT THE HORSES CAN NOT BE IN FRONT OF YOUR ENTRANCE TO YOUR HIVES,THIS WILL KEEP YOUR BEES FROM FLYING INTO YOUR HORSES AS THEIR COMING AND GOING FROM THEIR HIVE.

I asked a lady beekeeping friend of mine for her comments on this question since I know she has kept hives in relatively close proximity to horses for many years. Here is what she had to say:

I have kept bees for years with horses close by. They are across the road (barely room for two cars to pass). I have also heard that they do not get along well with horses. I have also heard of horses getting numerous stings. I have wondered how many of these problems could have been prevented if the bees were at a reasonable distance and beekeeping practices included keeping gentle strains of bees and the beekeeper maintaining the hives to lessen the late summer "robbing/aggressive" behavior that occurs. I mentored two girls that had 2-3 hives next to a fence with horses on the other side. When we worked the bees they came to the fence and we often took time to rub their head. In the year I worked with the girls there were no problems. They were keeping very gentle bees and doing a good job maintaining their hives. It is wise to remember that although all went well, bees are unpredictable.
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I find it interesting that she didn't elect to mention the period of time (perhaps a two or three year duration) when horses were kept in an adjacent field to her hives and the horses could come within about ten feet of her hives (separated by a wooden fence). As I recall, they did present a problem for her but I believe it was mostly a problem with their owner and maybe not so much with the actual horses. (He eventually sold the property so the problem resolved itself). I think she makes a good point about the bees' change to a more aggressive nature in the fall and how this could possibly not be a good situation with horses close by.

dumas did a fine job in solving hes or her problem,
good common sense!

there are many other ways, 2 examples...

I would give at least 40 feet, if that can't be done, you can erect a fence about 15 feet from the hive, so the bees have to fly almost vertical when they come and go.
Konrad