Well, she's entitled to her opinion. Some people don't believe in keeping cage birds, or reptiles, or... or...
BUT. If she's working at the vet clinic and voices such an opinion, I would tell the vet as well.
"I'm sorry to have to leave your services here, but your staff doesn't approve of my choice in pet, and with that atitude towards a large portion of pets that I keep, I just don't feel comfortable spending my money here. There's more to pets than just dogs."
Her attitude is lousy, especially for anyone dealing with the clients.
I have a vet tech next door to me who said "I don't believe in feeding animals to other animals."
I then gleefully pointed out what a COMPLETE hypocrite she is, since she owns cats and dogs. Since she doesn't use any vegan kibble she feeds processed animals to HER pets, and at least my snakes are more honest!
She doesn't like me much. I really don't mind that she doesn't like me.