In most cases, a veterinarian is under no legal duty to treat an injured animal. But once a vet agrees to treat a pet, stopping while the animal still needs attention may lead to malpractice liability.
Many vets treat injured or sick strays that wander in, just because they love animals. Some states—Massachusetts, for example—reimburse a vet a nominal amount for taking in a stray dog that is sick or injured. (Mass. Gen. Laws Ann. ch. 140, § 151B.)
A vet may humanely destroy (euthanize) a dog without the owner's consent in an emergency. If, for example, a critically injured dog is taken to a veterinarian, and the owner is unknown or unreachable, the veterinarian will not be held liable for damages for euthanizing the dog.
Some owners bring pets to a veterinarian, leave them, and never return. When this happens, the vet is not responsible for feeding and caring for an animal indefinitely. To be fair to both vet and owner, many states now have laws that set out a procedure for veterinarians to follow.
California law, for example, deems an animal abandoned if its owner doesn't pick it up within 14 days of the time agreed on by the vet and owner. The law requires a veterinarian to try, for at least ten days, to find a home for the animal. A vet who can't place an animal with a new owner may humanely destroy it. The veterinarian may not turn the dog over to a pound or let it be used for scientific experimentation. (Cal. Civ. Code § § 1834.5, 1834.6.) Dog owners are to be notified of these rules by a prominent sign in the vet's office or a conspicuous notice on a receipt.