by Michelle Graf

Created on: February 26, 2010   Last Updated: February 27, 2010

If you've ever looked under the tail of a young kitten, declared them a girl or a boy, and chosen a name, only to find out eventually that Lucy is a boy, or Chester is a girl - then you are not alone.  Accurately identifying the gender of a young kitten can be difficult unless you understand their developing anatomy a bit.

The external genitalia (testicles) on a male kitten do not 'drop' or become readily visible in their first weeks of life.  In fact, they commonly do not appear until the fourth month, and sometimes even later.  As a result, they all look like girls at the back for the first few months.

Confound the confusion is that only the tip of the male penis is visible, which looks like a small slit opening below the rectum.  The female has a small opening below the rectum as well.

The trick is, the distance between the two openings.  In the male, mother nature leaves a space between the rectum and the penis for the testicles to come in when they are ready.  In the female, no such accommodations are necessary. 

Holding the kitten with its backside facing you, lift the tail out of the way.  You should clearly see the rectum directly under the base of the tail.  Below the rectum, you will also see a small opening.  In girls, there is very little space between the two openings.  In boys, there will be a space to accommodate growing testicles.  The size of the space will vary a bit depending on the age of the kitten, but in general, it will be about 1 cm or a little less than half an inch. 

Determining gender in a kitten less than a few weeks old is very difficult as everything is proportionately much smaller, which makes it easier to make a mistake.  And some kittens are just harder to tell than others.  Kittens with long hair or dark fur can be harder to sex than white, short haired kittens, just because all the parts are easier to see.

All kittens should be examined by a vet by the age of 6 weeks for their first vaccinations, and by then a vet should be able to tell in almost all cases for certain if you have a male or female kitten.  Sterilization can take place as early as two months, and should in any event be performed before sexual maturity, which usually occurs before six months.  In rare cases, the actual gender of the kitten is not accurately determined until then.

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