I have been told you can.
I just had a bad deal with a girl over the horse I had.
I bought her, was told she was in perfect health, the girl got her from Canada when she was three, and she was now four. She said she had broken her and done everything.
I got the Warmblood mare home, and found out immediately from a vet that she had a pretty serious heart murmur, and she was between 6-7 years old.
I asked the girl if she had had her vetted before, and she said yes many times.
I told her about the heart murmur, and requested copies of all the mare's previous vet records (the girl told me a vet had never told her that before, which is why I wanted the proof)... and never heard back from her.
I had put a deposit on the mare, and was going to do a lease-to-buy to finish paying for her. After that incident, I never sent her anymore money. After not hearing from her for a couple weeks, I sent her an e-mail in attempts to contact her again. I basically told her that I was not willing to pay that price we stated anymore because of the heart murmur. That in order to Event with this mare like I wanted, I would have to do further heart tests and evaluations to find out just how severe it was. And I wanted to do this, because I really liked the mare. I told her that if we could come to an agreement, that'd be great, but I wasn't sending any payments until we could come to one, and I saw that her vets had cleared this mare with "no heart murmur". I told her if she didn't want to work something out, she could come pick up the mare then, and the lease would be terminated, with no purchase at the end obviously either.
Never heard back from her.
I have since sold the mare, she was not what the girl told me she was.
She, honestly, I believe had neurological issues. She was very two-faced, and almost spaztic. I have to wonder if she was beaten at some point in time, since obviously the girl didn't get her when she was three. Who knows where the poor horse had come from.
I just didn't have the time to work with her, she had too many issues that I was unaware of.
I have been waiting to see if she was going to come at me. But honestly, she'd be stupid to. I have Navy Legal on my side (My husband is Military) and she wouldn't win.
She obviously got scared when I found out everything and confronted her, and just wanted to wash her hands of the mare for only the deposit I gave her.
Yes, if its something serious, I think most definitely you could sue.