We used to get bones from a local slaughter yard in the UK for still life drawing so is that what you mean?
A lot of Vet Training Centres/Universities will euthanise unwanted horses to use in teaching so I'd try them first
Oh no no no, I don't want it in parts!! I don't think I could stomach that. Me and my art buddies at uni require a big size adult (preferably a mare). We intend to imitate a certain upside down horse statue by artist David Cerny. Google it.
I appreciate not many owners will allow this, and I don't blame them. But me and pals don't know where to go and ask. We would pay for the borrowing. By the way, I'm from UK.