Gender in rats can be discerned as early as 4 days after their birth. But these kids usually do not sell because they eat mommy's milk. Remember that at this age you can make mistakes. If you want to distinguish between the pups by sex, it can be done only in comparison. While the rats still live with my mom, to take them in hand undesirable, as it may be confused by a strange smell, and she will refuse to feed their children.
Rats at the age of 2 weeks, you may notice that the males nipples are not visible when the females are still poorly covered with fur of the abdomen is clearly visible Breasts. But there are different cases, sometimes the males have well developed nipples, so that this method can be used only as an auxiliary.
Put the rat on the arm so that they could see the sex organs. In females the distance between the anus and the vagina less than males. Also in male-rats, you notice two dark spots, which are located almost at the tail, with age, they will start to increase.
Approximately 4 weeks from the date of birth of the males are clearly different from the opposite half. At this age, they have clearly differentiated the eggs to 2-3 months to reach large size. Genitals "strong" half located closer to the tail. Some people for this reason and do not want to buy males. Although it is noticed that they are calmer and females rarely bite.
If you can't discern gender by yourself, ask the seller to explain to you. Do not purchase differenthollow rats from the same litter, sooner or later there will be a mixture of blood and the light can appear the sick kids. If you want to buy for two rats, but one sex, it is better to buy females, men can fight in puberty. When you need one animal, then the best option is to purchase the male.