Prohibits the humane killing of a dog or cat that is a companion animal unless the animal poses an immediate physical threat to a person or is in extreme distress and would suffer further as a result of a delay in seeking veterinary care. The bill makes a violation a Class 2 misdemeanor, with any subsequent violation a Class 6 felony. The bill exempts from the prohibition any veterinarian or other authorized person who euthanizes a companion animal under Chapter 65 (§ 3.2-6500 et seq.) of Title 3.2 (Comprehensive Animal Care).