A licensed veterinarian who, in good faith and without compensation, voluntarily or at the request of a government official provides emergency care or euthanasia for humane reasons to an animal will not be held legally responsible. They can be held legally responsible if acting with careless disregard for the rights of the owner of the animal.
Emergency care or treatment
A licensed veterinarian who in good faith administers emergency care or treatment, or euthanasia for humane reasons, to an animal, without compensation, either voluntarily or at the request of a state or local governmental officer or employee, is not liable for civil damages for good-faith acts in the administration of such care or treatment. This immunity does not apply in the event of a wanton or reckless disregard of the rights of the owner of the animal.