Endoscopic sexing in turtles and tortoises: 467 cases (2007–2017)

Abstract

Background This multi‐institutional retrospective study evaluated the feasibility and safety of endoscopic sex identification in 467 turtles and tortoises, representing 10 species. Methods Medical records of turtles and tortoises that underwent endoscopic sex identification at the University of Georgia, New England Aquarium and Turtle Conservancy were reviewed for presurgical management, anaesthesia, endoscopic equipment and surgical techniques, endoscopic results and complications. Results The majority of animals weighed less than 200 g, were fasted and anaesthetised using an injectable combination of ketamine, dexmedetomidine and morphine or hydromorphone, supplemented by local lidocaine at the prefemoral site. Anaesthetic reversal using atipamezole alone or in combination with naloxone was routine. For uncomplicated procedures, mean total anaesthesia, surgery and recovery times were 22, 4 and 18 minutes, respectively. All animals were placed in lateral recumbency for a prefemoral endoscopic approach to the coelom using a rigid telescope and sterile fluid infusion to visualise the gonads. Sex identification was definitive in 99.4% (n = 464) of the animals. Iatrogenic bladder perforation was the most common complication (n = 5), which necessitated extended anaesthesia and surgical time for repair. Only a single anaesthetic‐related death was reported, which was associated with human error and drug overdose. Conclusions This is the first large‐scale study to retrospectively evaluate endoscopic sex identification in multiple chelonian species. Results suggest that endoscopic sexing is a safe, accurate and practical means for sex identification in turtles and tortoises, and represents a valuable tool in their reproductive management.

Testosterone identifies hatchling sex for Mojave desert tortoises (Gopherus agassizii)

“…Coelioscopy has proven to be a safe and accurate method for identifying sex in a large number of chelonians of different species 32 . Previous studies have demonstrated that injectable anesthetic agents alone may be insufficient and that the addition of local lidocaine improves anesthesia overall 33 .…”

“…In addition, the stage at which gonads can be reliably identified is consistent within a species, but can be variable between species. For example, the Chinese box turtle ( Cuora flavomarginata ) exhibits obvious gonadal dimorphism at hatching and can be reliably sexed as soon as the yolk sac has been absorbed at about four months and 35 g bodyweight; however, the gonads of radiated tortoises ( Astrochelys radiata ) become difficult to differentiate below about nine months or 100 g body weight 32 , 33 . To mitigate such risks, it is therefore wise to start with the largest animals in the cohort, and progress to the smaller animals until safety margins or certainty of gonadal identification decrease.…”

“…When the captive hatchlings that we challenged with FSH were approximately 1.3–1.6 year old in April 2021 ( n = 33), we definitively sexed them using endoscopic surgery; i.e., visual inspection of the gonads from within the coelom 19 , 32 , 33 ). We fasted tortoises for 24 h prior to surgery to prevent regurgitation during anesthesia.…”