F. Any person who (i) tortures, willfully inflicts inhumane injury or pain not connected with bona fide scientific or medical experimentation, or cruelly and unnecessarily beats, maims, or mutilates any dog or cat that is a companion animal whether belonging to him or another and (ii) as a direct result causes serious bodily injury to such dog or cat that is a companion animal, the death of such dog or cat that is a companion animal, or the euthanasia of such animal on the recommendation of a licensed veterinarian upon determination that such euthanasia was necessary due to the condition of the animal is guilty of a Class 6 felony. If a dog or cat is attacked on its owner's property by a dog so as to cause injury or death, the owner of the injured dog or cat may use all reasonable and necessary force against the dog at the time of the attack to protect his dog or cat. Such owner may be presumed to have taken necessary and appropriate action to defend his dog or cat and shall therefore be presumed not to have violated this subsection. The provisions of this subsection shall not overrule § 3.2-6540, 3.2-6540.1, or 3.2-6552. For the purposes of this subsection, "serious bodily injury" means bodily injury that involves substantial risk of death, extreme physical pain, protracted and obvious disfigurement, or protracted loss or impairment of the function of a bodily member, organ, or mental faculty.