Rabies is always fatal in any warm blooded animal that contracts it, so there are no options. Annual vaccination is the only protection. Protection against biting insects is helpful in maintaining the normal health and condition of pastured horses. Fly tags in manes and tails, pour-on materials that provide some residual effect and environmental aspects are all helpful. Face fly masks should be of the break-away variety so if horses get the mask caught, they can get loose.
Horses are continuous grazers and do best when pastures are a grass mix with minimal legume.
Fescue is not considered a safe pasture for pregnant or nursing mares, but is quite satisfactory for non-pregnant mares and geldings. By keeping it mowed and preventing the presence of seed heads, the danger of endophyte toxicity is reduced. By proper management and preventing any grass to reach the seed head stage, any risk of ergot toxicity is likewise avoided. The avoidance of clovers in a pasture mix avoids other problems. The white clovers, especially alsike tends to cause a condition called photosensitivity dermatitis.