Rat Health Care & Information

Sexing Rats

Your Rats
Breeding & Showing
General Info

The following pictures demonstrate the difference between male and female rats. It's very easy to tell the difference as they reach 5 weeks and above and with a little bit of practice and close observation of the key differences, hopefully the following pictures will demonstrate this.

At 2 hours old and it is possible to tell the sexes of your kittens. In the 1st picture the buck is on the left and the doe on the right, note the larger 'lump' where the penis is on the buck. In the 2nd picture, the doe is in the foreground and the buck behind. I sex my kittens within the first 48 hours of being born, but I do recheck later as well as it is still possible for even a trained eye to make mistakes when they are this age.

At 4 days old - buck on left, doe on right in both pictures. Notice the gap between the does urethra and anus are much smaller than the gap between the penis and anus of the buck.

At 9 days old on a darker coloured rat the difference is very noticeable as the doe clearly has nipples showing in the left hand picture - does have 6 nipples on each side, totalling 12 in all. You can already see the hint of the testicles shape appearing on the buck in the right hand picture. You can see the navel in the centre of the stomach on both buck and doe at this age. It looks a little like a nipple at this age, but bucks only have the navel while does have 12 nipples up the side plus the navel!


Also at 9 days old for comparison. In the 1st picture the doe is on the left and the buck on the right and in the 2nd picture the buck is on the left and the doe on the right, but the nipples are not obvious on lighter (in this case Siamese) kittens.

At 14 days old. The rats are fully furred now but the gap is still pretty obvious. The doe is on the left and the buck on the right.

At 5 weeks old. As you can see the testicles have descended on the buck in the left hand picture and it is very clear which is which now. By this age, the kittens must be separated as the buck is capable of siring litters and the doe is capable of becoming pregnant. They don't always have the immediate desire to mate each other but it does happen, so it is important to separate to avoid the risks of unwanted kittens from a doe that is too young to be breeding yet.

As adults, doe on left and buck on right. The difference is very clear and bucks testicles are very apparent! When a doe is in season, the vaginal hole becomes dilated and after mating it's often possible to see a vaginal plug where the sperm has made a solid 'cork' to keep it in place.

Article written by Estelle

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Images & Text Copyright 2008 Estelle Sandford, Alpha Centauri
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Last modified: February 08, 2017