horses and garden lime question

I was told to put garden lime down around in the pasture to cut down on the odor and flies, which it does work. My question is: Is garden Lime toxic to horses? I know I should have ask this a long time ago, but I just read somewhere that it is toxic to horses, but it has never bothered mine.

We use limestone screenings in our dry lot to keep the mud under control. We keep the horses out of it until it gets a good rain on it.
I'm sure the garden lime would be the same. Once its rained on it should be fine. Its the dust you have to worry about them inhaling.

Oh, ok, I will have to put it down right before it rains or water it. Thanks