I am not aware that any such tests have been accepted as valid. Annual vaccination is still recommended by the American Association of Equine Practitioners. They are the organization that sets the standard for Equine veterinary medicine and when the tests support vaccinating every 3 years they will change the protocol.Actually in recent tests they found that a horse only needed about 4 rabies shots in their lifetime, the problem is, which four ?
Rabies is an extremely effective vaccine. IMO if we continue to give it to horses every year, we will do the same thing to horses we did to dogs.
Once every three years is enough for mine.