Several pharmaceutical manufacturers offer rabies vaccines, and four are licensed for use in horses. A booster given at 12-month intervals is all that's needed after the initial vaccination. He points out that some states prohibit persons other than licensed veterinarians from purchasing or administering rabies vaccine. But many veterinarians, knowing the importance of this vaccine, will administer it for little more than cost, simply to ensure that their patients get vaccinated properly and regularly and that the vaccine itself is handled properly. Some veterinarians, he says, even offer low-cost clinics for horses similar to the rabies clinics for dogs and cats that you'll occasionally see advertised in your local newspaper or at your Humane Society or veterinarian's office.
Rabies vaccine is effective only when administered prior to exposure.
The vaccine has no effect after your horse is bitten or otherwise exposed. No such treatment exists for horses or any other animals. Keeping your horse on a regular schedule of rabies vaccinations is tantamount, of course. Never approach such an animal yourself, and get your own animals out of harm's way until the suspect animal is removed. The Web site contains a number of free, downloadable articles as well as statistics and links to related sites.