Does your horse get fed any raw grains? Oats, etc. Two of my friends have mares that constantly get absesses and they love to feed rich, raw grain mixtures.
I feed no raw grains, only low-starch blended feeds when in heavy work (replacing calories we use), and I've yet to have an absess. I don't think it's strictly coincidence. Some horses seems to have a lower tolerance for sugars (laminitus, IR). I personally think absesses fit into this category. There's certainly no environemental reasons for my two friends' horses to have any issues - dry as a bone out here. Their feet are rock hard and STRONG.
The epsom soak does seem to draw infection out and help them heal faster. I'd be soaking even before the thing blows out. Soften that hoof up and encourage healing. Jmo.