(a) Except as provided in subsection (b) of this Code section, the use of sodium pentobarbital or a derivative of it shall be the exclusive method for euthanasia of dogs and cats by animal shelters or other facilities which are operated for the collection and care of stray, neglected, abandoned, or unwanted animals. A lethal solution shall be used in the following order of preference:

(1) Intravenous injection by hypodermic needle;

(2) Intraperitoneal injection by hypodermic needle; or

(3) Intracardial injection by hypodermic needle.

(b) Notwithstanding subsection (a) of this Code section:

(1) A chamber using commercially bottled carbon monoxide gas which was used on July 1, 1990, for euthanasia of dogs and cats by any animal shelter or other facility may continue to be used for such purposes by such animal shelter or facility if such animal shelter or facility notifies the Commissioner of Agriculture, in writing, on or before August 1, 1990, that such a chamber was in use by such animal shelter or facility on July 1, 1990. However, a chamber which causes a change in body oxygen by means of altering atmospheric pressure or which is connected to an internal combustion engine and uses the engine exhaust for euthanasia purposes shall not be permitted under any circumstances; and

(2) Any substance which is clinically proven to be as humane as sodium pentobarbital and which has been officially recognized as such by the American Veterinary Medical Association may be used in lieu of sodium pentobarbital to perform euthanasia on dogs and cats, but succinylcholine chloride, curare, curariform mixtures, or any substance which acts as a neuromuscular blocking agent may not be used on a dog or cat in lieu of sodium pentobarbital for euthanasia purposes.

(c) In addition to the exceptions provided for in subsection (b) of this Code section, in cases of extraordinary circumstance where the dog or cat poses an extreme risk or danger to the veterinarian, physician, or lay person performing euthanasia, such person shall be allowed the use of any other substance or procedure that is humane to perform euthanasia on such dangerous dog or cat.

(d) A dog or cat may be tranquilized with an approved and humane substance before euthanasia is performed.

(e) Euthanasia shall be performed by a licensed veterinarian or physician or a lay person who is properly trained in the proper and humane use of a method of euthanasia. Such lay person shall perform euthanasia under supervision of a licensed veterinarian or physician. This shall not be construed so as to require that a veterinarian or physician be present at the time euthanasia is performed.

(f) No dog or cat may be left unattended between the time euthanasia procedures are first begun and the time death occurs, nor may its body be disposed of until death is confirmed by a qualified person. (g) The supervising veterinarian or physician shall be subject to all record-keeping requirements and inspection requirements of the State Board of Pharmacy pertaining to sodium pentobarbital and other drugs authorized under subsection (b) of this Code section and may limit the quantity of possession of sodium pentobarbital and other drugs authorized to ensure compliance with the provisions of this Code section.

(h) This Code section shall not apply to any animal shelter or other facility located in a county having a population of 25,000 or less according to the most recent United States decennial census.