I’m not bashing the trainer for feeling ownership of the pony. I’m not disagreeing that OP appears to have lied on this forum. I would never say college education makes you honest. We would have no stock market fraud, absconding lawyers, or crooked accountants if that were so.
I am also not arguing that the trainer probably can provide a better home for pony.
However the question of who provides a better home is immaterial legally in the case of a horse. Ownership goes to the person with the bill of sale. Though we may feel a horse is family, legally they are a possession like a truck and not a child custody case.
My main point though is that this is probably a civil case before it is a criminal case. In civil cases you need to pay lawyers to sort things out before you can get law enforcement. So far there is no evidence of either party doing so.
And note that while a retaining fee for a lawyer might be $2000, you are probably looking at over $10,000 in the end. I don’t know too many lesson programs that have the spare cash to go down that kind of legal rabbit hole.
In other words, in such cases civil litigation is generally out of the question financially for either party.
I don’t know what police have or haven’t done, but it’s clear they haven’t arrested OP despite her admission she has the pony.
Also the pony was either a giveaway or on free lease. In neither case is board ever paid. If I have a horse on free lease for my exclusive use for 5 years and owner wants her back, I can’t say “pay me 5 years back board before I give her up.” If anything I would offer to buy the horse from the owner.
So since the claim for back board is spurious and the pony is not actually abandoned if OP is asking for it back, I’m unsure whether the lein that transferred ownership to the trainer is 100 % legitimate.
As far as there being a damages claim against the pony stemming from a lesson incident, in such cases the action is taken against the entity with the best insurance. The pony is in a lesson program that hopefully has proper insurance and under the direction of the trainer. There would be no reason to name the owner of the pony, at least if she has no insurance or assets. And indeed trainer probably acted and spoke as if she was the owner at that point.
People often free lease their horses to lesson programs and you do not hear of such absentee owners getting sued because of an accident that happened when they were hundreds of miles away.
Anyhow my overall point here is just that once the pony is gone, there isn’t much the trainer can do other than make noise on social media.
As I said, there actually is much less legal redress out there than you might think, especially for situations with low dollar value but high emotional investment. We live in such an apparently legalistic and law driven society that it’s often surprising how few legal remedies there are for disputes that are primarily interpersonal.