Euthanasia of reptiles
Stephen L. Barten DVM, News from the North Bay, Feb 1994
Euthanasia, the act of humanely killing animals that are hopelessly sick or injured, is a controversial topic. Some people, including animals rights advocates, don't believe euthanasia should ever be performed, regardless of the circumstances. However, many of these same people also oppose other things that herpetologists traditionally do: the keeping of animals in cages, feeding of prey items (rodents, poultry, fish, insects) to carnivorous reptiles and the collection of animals from the wild. (I often wonder if animals rights activists oppose giving a dog a flea bath or treating it for worms, because that would violate the rights of the parasites.)
Most herpetologists and veterinarians alike are strong supporters of animal welfare rather than animal rights--believing that animals may be kept as pets, kept in zoos and used for food and research, but it is our moral obligation to provide them with optimum captive conditions, balanced diets, pay attention to their behavioral needs and keep them from pain and suffering. Occasions arise when the only way to alleviate pain and suffering is to humanely euthanize captive herps. These may include irreversible illness or injury, sacrificing a small number of a larger group to diagnose a disease outbreak or culling an overcrowded collection. Many prey animals, especially rodents, are euthanized prior to feeding them to captive reptiles. This is a special circumstance in that chemical agents should not be used or the reptile eating the euthanized rodent could suffer toxic affects. When euthanasia is performed it must be performed in a humane manner.
Decapitation is an easy way to kill a reptile in that no special equipment or drugs are necessary. Nevertheless, the brain of a decapitated reptile may remain active for up to an hour, so decapitation by itself is inhumane. It may be used if the brain is pithed, or destroyed by the insertion of a probe, immediately afterwards. Some of you may have pithed leopard frogs in high school biology prior to their dissection.
Euthanasia can be done by destroying the brain with a sharp blow to the head, on the middle and just posterior to the eyes. This can be done in an emergency, as when an animal is found hit by a car, grievously injured but not yet dead and no other method is available. This is among the most common methods of euthanizing feeder rodents. Care must be taken to perform this method properly, as a soft or misdirected blow could injure the patient without killing it. Large reptiles (crocodiles, monitors and big tortoises) can be killed with a gunshot of appropriate caliber to the brain.
Inhalation of various gasses can be used to euthanize animals. Some of the gasses that might be used are chloroform, methoxyflurane and carbon monoxide, among others. Disadvantages of this method include the need for some means to deliver the gas to an enclosed chamber holding the patient, the potential risk to the person if improper equipment is used and the difficulty in obtaining some of those agents. I once read a report of rats killed with chloroform causing sedation in the snake that ate him. This method is useful for venomous snakes in that no handling is necessary.
Freezing has been used as a humane method to kill small reptiles under one pound in weight. Although low temperatures do result in a state of torpor, the formation of ice crystals in the tissue is quite painful. Freezing should only be done to anesthetized animals.
The preferred method of performing euthanasia is the injection of barbiturates into a vein or into the coelomic cavity. This is how dogs and cats are euthanized when it is necessary. The technique is quick and painless, taking only minutes to perform by the intravenous route but up to several hours by the intracoelomic route. The later route should not be used if a post-mortem examination is planned. Barbiturates are controlled substances and must be administered by licensed veterinarians. Aggressive, dangerous or difficult patients may be sedated either by injection or with anesthesia prior to euthanizing. Injectable agents should not be used on animals intended for food.
In a perfect world euthanasia would never be necessary. Since it sometimes is, the goal of this column is to promote the use of humane methods and to educate readers that some commonly used methods, such as freezing and decapitation, are inappropriate.
Steve Barten, DVM, is a noted reptile veterinarian is, when he is not writing about reptile and other exotic veterinary medicine, or teaching and lecturing at veterinary conferences, in exotics practice in Mundelein, IL.
The following references on euthanasia are cited in the chapter on euthanasia in Manual of Reptiles (1992. Peter Benyon, Martin Lawton, John Cooper (eds.). Iowa State University, Ames, IA):
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