All veterinarians are legally allowed to euthanize dogs and other companion animals. However, veterinarians also have a right to refuse to perform euthanasia under certain circumstances.
Pet euthanasia is performed for a variety of reasons. A veterinarian generally performs euthanasia on a dog only when the dog is suffering and there are no other treatment options. When the owner is seeking euthanasia for other reasons, such as convenience, veterinarians have a right to refuse.
In addition, although euthanasia is generally performed by veterinarians, some states have laws allowing non-vets to put down companion animals. These euthanasia technicians may handle the actual procedure, rather than the veterinarian who saw the animal and spoke to the owner beforehand.