First things first, id get your dog cared for and not let the cost effect your decision unless it absolutely has to. You may be able to get your money back one way or another, but the decision to remove your dog's leg could effect you for years of your life. After your dog is cared for, im pretty sure that you can seek a malpractice claim the same way you would if it were a human. Best of luck to you, i care about my dog more than i do most people and i would be furious in that situation, so i feel your pain.