This is even more critical if dealing with a breeding animal. Examine the horse's markings carefully and be sure that the registration certificate matches. The vet can help with this at the pre- purchase exam. The integrity of the breed is dependant on the fact that horses match their registered pedigree. These documents take time to obtain, but are very important when purchasing registered, performance, or breeding horses.
Health records are equally important for all horses.
Documentation of past deworming, immunization, and the occurrence of major diseases is helpful. Often times this information is not available, so assume you have to start from scratch with a health management program. Insist on a negative Coggins Test. EIA is a blood borne, viral disease that has no vaccine nor any known cure. Every horse purchased should have a negative Coggins test on blood drawn within the last thirty days.