Sexing and Gavaging of rats

Sex Determination

(extracted from http://research.uiowa.edu/animal/mp7.jpg)

Sexing is based upon anogenital distance. Male rats have a greater distance between the anus and urogenital opening. As compared to the females, males have a larger genital papilla. Well unlike the case of dogs, you cant tell the gender apart based on the testicles and phallus. Rats have open inguinal rings and can retract their phallus and testicles into their abdomen. How convenient. Thus the lack of testicles and phallus upon visual observation does not indicate that the rat is a female.