Euthanasia in exotic pets: what the evidence says for fish, reptiles, birds and small mammals

Under AVMA guidance, hypothermia and removing fish from water are unacceptable methods. One study found that prolonged immersion in buffered MS-222 at 1,000 mg/L killed only 7% of adult goldfish. A second study found the same concentration worked in juveniles. Because of results like these, a two-step approach is still recommended for pet fish: anesthesia first, then a secondary method such as pithing, decapitation, or an intracardiac injection.

In reptiles, Petritz recommends confirming heartbeat with Doppler or ultrasound rather than a stethoscope, and listening for at least one to two minutes because heart rates are slow. In a study of sedated leopard geckos, intracardiac injections stopped the heart right away, while intracoelomic pentobarbital took 30 to 35 minutes. Six of nine geckos given intracardiac lidocaine began breathing again and regained a heartbeat hours later, and six of nine given intracardiac KCl had severe muscle spasms. The authors advised against both drugs at the doses studied in that species.

Results for oral and cloacal pentobarbital have been mixed. In red-eared sliders, 75% of turtles given the drug by the cloacal route leaked solution and needed a rescue IV dose. The oral route worked, but cardiac arrest took an average of 18 hours. In bearded dragons, oral dosing led to cardiac arrest after about six hours on average, and in feral green iguanas, every animal needed a rescue IV dose.

For pet birds, AVMA guidance allows IV barbiturate only if the injection doesn't cause fear or distress, so deep sedation or general anesthesia beforehand is strongly recommended. The usual veins are the right jugular, medial metatarsal, and ulnar, and in small birds the jugular may be the only workable option. Intracardiac, intracoelomic, and intraosseous routes are acceptable only in unconscious birds, and injections must avoid air sacs and pneumatized bones. Thoracic compression in a conscious bird is unacceptable.

Small mammals are handled much like dogs and cats. Because rabbits and rodents are prey species, heavy sedation or anesthesia is recommended first. Intrarenal injection is an acceptable method in unconscious rabbits, but in one study it was slower than IV, and 30% of rabbits needed a rescue IV dose of pentobarbital. Petritz has also seen intraperitoneal injections delay cardiac arrest in her own practice.

Petritz included example protocols for each group. All of them start with sedation or general anesthesia before the euthanasia solution is given, and she stressed that there is no single correct method or dose. For reptiles, she adds IV or intracardiac KCl once the patient is unconscious, which she has found speeds cardiac arrest considerably.

Pentobarbital in buried remains can poison scavenging wildlife, including bald eagles. Petritz recommends cremation when possible. When clients take remains home for burial, she recommends explaining the risks and local burial rules, ideally on the signed consent form.