You'll have to see a local attorney to see if there is anything that can be done. I think there might be some negotiation possible to avoid litigation. I agree with the others that there is no assured result. In addition to the case I cited for the law, some older cases that might guide as to how hard you might want to fight. Don't focus on the result of any of them, but on the discussion. None have your exact facts.
Good for you on nuisance, bad for privacy:
GTE Mobilnet of South Texas v. Pascouet, 61 SW 3d 599 - Tex: Court of Appeals 2001
Good for you on privacy:
Baugh v. Fleming, Tex: Court of Appeals, 3rd Dist. 2009
Survellence cameras and privacy may be nuisance:
Webb v. GLENBROOK OWNERS ASSOCIATION, INC., Tex: Court of Appeals, 5th Dist. 2009
By the way, were there any official discussions during zoning hearings like a variance? Did you give anything up like attending any zoning hearings because of the vet's promise to mitigate any nuisance?