Fancy Rats Sexing Guide
Adult rats can be sexed from very early on. The best way to sex a rat pup is before the fur grows in and thus the nipples are still visible on the girl. These will be in two rows of six. Records need to be kept as the litter grows as you may need to record markings against gender. Slightly dampening the fur of your rat may help make nipples more visible.
Female rats are called does and male rats are called bucks.
The best way to sex a rat is to look for the distance between the anus and the genital. This is always much greater in males compared to females.
- Females: Have obvious nipples, best seen before hair grows in.
- Males: have a large bulge at the base of their tail, usually visible from 4 weeks and obviously by 6.
You can also make use of a container with a clear bottom for older animals and observe from below. Male rats do have the ability to retract their equipment, but as they relax or warm up they should drop these.
It is possible to have hermaphrodite rats (that is both male and female) and these can be fertile. If you suspect this then you need to get advice from responsible breeders or a vet experienced in rats. This does not mean the rat must be kept alone, just that you may need to spay or neuter to make this safe.