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How To Sex Small Mammals



How to Sex Small Mammals

A great way to identify the gender of the small mammal you’re holding is to look for punctuation. Yes, you read that right! If you peer at the underbelly of a female near her back end, you will usually find that her sexual and anal organs are lined up like an exclamation point. If you spot two dots in a row that resemble a colon mark, you’ve got a male on your hands.

Quit snickering! Figuring out the gender of a hamster, guinea pig, or other small mammal who comes into your shelter is no laughing matter. After all, if your little tenants get busy lovin’, it can result in even more unwanted small pets, and pretty soon your shelter will look like a Little-Critter Free-Love Commune. When examining creatures this small, it’s all in the details. Read on to find out how you can easily tell the boys from the girls.

1. Determining Gerbil Gender
You can sex a gerbil starting at the age of four to six weeks by peering at the animal’s underside. To minimize stress on the animal and also make handling easier, place the gerbil in a large clear box to search for a pair of large testicles; if you spot them, you’ve got your answer to the gender question. Since the sexual and urinary openings of female gerbils is much less obvious to the naked eye, it helps to look for small nipples on the underside. Still stumped? The distance between sexual and anal organs is longer on the male than it is on the female.

2. Holding Off Hamster Hanky-Panky
Using the clear box trick, look for large testicles on the underside of the hamster. In males, there will also be a bigger gap between the urinary and anal openings. The perineal area (or the area between the genitals and the anus) comes to a point at the base of the tail in females, but this area looks more rounded in males.

3. Is This Mickey or Minnie Mouse?
As with the other small mammals, the distance between the anus and genitals of mice is longer in males. In addition to the closer spacing, female mice have a small teardrop-shaped vagina extending down from the anus. Both openings are very close together and appear to be connected. Female mice also have two rows of nipples running vertically down their bellies.

4. Playing Rat Roulette
Since you don’t want to say, “Oh, rats,”after making a mistake in gender distinction, remember that male rats have a stronger odor than female rats. As with other rodents, male rats have a greater distance between sexual and anal openings, and their testicles are no shrinking violets.

5. No Guinea Pig Guessing
Male guinea pigs have obvious scrotal pouches and large testes. The sexual organ of a male guinea pig will look more like a belly button right above the anal opening. Very little space separates these parts; if you are looking at a young guinea pig, gentle manual pressure can help you distinguish between them. The organs of female guinea pigs are also close together and look something like the letter “Y”; this Y-shaped depression can be seen even in immature females.

6. Making Rabbit Rulings
Figuring out the sex of young rabbits can be tricky, but it gets a little easier as they mature to about 10 weeks old or so. Put your hand under the rabbit and feel around for furry testicles; keep in mind that testicles in rabbits move freely from the scrotum to the abdomen. On male rabbits, you will also see a tubular protrusion, whereas the female reproductive area will simply look more like a slit even when pressure is applied.

Courtesy of
From the July-August 2000 Issue
Animal Sheltering Magazine


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