Your cat just delivered a litter of adorable kittens but how can you tell the boys from the girls? It can be difficult to distinguish between the genitals of male and female kittens, especially when the babies are only a few days to weeks old. By learning about the reproductive anatomy of cats and comparing between male and female kittens, you have a better chance of telling them apart. Be aware that even breeders and veterinarians have made errors when trying to sex very young kittens.
All kittens should be born with two anatomical openings just below the tail. One is the anus and the other one is the genital area. The primary way to tell a female kitten from a male kitten is by comparing the distance between the anal opening and the genital opening. Rarely, a kitten may be born without an anus. This is a birth defect and is considered very serious and life threatening. If you notice that your kitten only has one opening under the tail, contact your family veterinarian and have the kitten examined as soon as possible.
For male kittens, the space between the anus and the tip of the penis is longer than the space between the anus and the vagina. This extra space allows for the testicles to descend out of the body cavity and into the scrotal sacs later in life. After about 4 to 6 weeks of age, the testicles can be palpated. They would feel like small peas in the space between the anus and penis.
For female kittens, since there are no testicles, the space between the anus and vagina is short. The shape of the vaginal opening is a vertical slit, unlike the small circular opening of the penis.
Comparing kittens of different sexes can help you understand and learn how to sex males and females. Remember, comparing kittens of the same age will give you a much better understanding than kittens of vastly different ages.
Also, if there are any calicos or tortoiseshell kittens in the litter, chances are, these are female.