And even bloods being pulled isn't failsafe. A similar thing happened on our yard recently (a horse came for schooling because of his 'bad behaviour' which turned out to be due to hock & stifle pain). The vet said he had probably had his joints medicated prior to being sold to his current owners and that a blood test won't pick that up after however many weeks, can't remember exactly, but the point is you have a lame horse, get it injected, wait a couple of weeks and sell it for megabucks while it still appears sound then deny all knowledge when it starts to go lame for the new owners. Some people are absolute shits.A friend brought a horse which down the line decked him several times then went lame, he knew there was investigation for lameness with a prior owner done at our vets, the vet couldn't share the record without written permission from the prior owner, the prior owner wouldn't give the permission to the vets even though she had told my friend verbally she would. They tried all sorts to no avail, no loop holes found. It's effectively doctor patient confidentiality/medical records so the laws around it are very tight, a court could unseal them but you would have to have evidence up front to justify them doing so which would be tough to prove without bloods pulled prior to purchase showing something.