Antinociceptive and physiological effects of subcutaneously administration of fentanyl in Trachemyssp. (Testudines: Emydidae)

Control of pain in reptiles is a challenge and there is few information about it. This is the first study that evaluate fentanyl on testudines, of genus Trachemys sp. A total of 30 animals were used, 15 T. dorbigni and 15 T. scripta. Two groups composed of ten specimens each were created, as well as two control groups of five animals, for each species. A dose of 0.05 mg/kg of fentanyl was administered to experimental groups, and a 1 mL/kg physiological solution was administered to control, all subcutaneously (SC). The reptiles were monitored in terms of the color of the oral mucosa, cloacal temperature and heart rate, response to the nociceptive stimulus, and myorelaxation. The effects started 10 minutes after the administration and lasted 134 ± 26 minutes and 120 ± 20 minutes for T. dorbigni and T. scripta, respectively. In 80% of the animals, there was a total absence of reaction to a nociceptive stimulus, with an average duration of 39 ± 10 minutes for T. dorbigni and 30 ± 12 minutes for T. scripta. It was concluded that fentanyl 0.05 mg/kg SC is capable of promoting the absence of nociceptive response in Trachemys sp.