Sexing or Gender Determination in Small Mammals

Key Points

• Examine anogenital distance to determine gender in neonatal rodents and in chinchillas of all ages. The distance between the anus and the urogenital region is relatively short in female rodents and longer in males.
• Sexing can be challenging in chinchillas since the clitoris and penis morphology appear quite similar, however the anogenital distance is approximately twice as long in males.
• Use external anatomy to sex adult hedgehogs, sugar gliders, ferrets, rabbits as well as rodents such as the guinea pig, rat, and hamster.
• The testicles may be retracted into the abdomen of the adult rabbit as well as many species of rodents.
• Mature males are often larger than females, except in chinchillas where the females are generally larger.