It's hard to know just based on what you're saying, but if she needs a crupper just for a normal ride, and she wants to bite when you put on her saddle, it sounds like maybe her saddle doesn't fit. At least, that would be my first guess.
I'm no expert here, so take it with a grain of salt.
I know from experience that horse owners, barn owners, and instructors can all talk a great talk about the healthcare their horses get, and how well their tack fits, but a lot of times there is a lot of exaggeration and even misinformation there. And it's hard to talk about things like this to them when you're leasing, because they can be really dismissive.
"Saddle fit -- it's a no brainer!"" - random person
Last edited by ACinATX; 08-23-2020 at 08:59 PM.