Q: I have a young Syrian hamster named Marshmallow. I am not sure if it is male or female. I would like to know what the gender of my hamster is. How do you properly sex a hamster?
A: It was good thinking to name your little one Marshmallow, because it will suit him or her, whatever the gender! If Marshmallow is definitely a Syrian hamster, it is almost impossible not to be able to tell the sex after about it reaches 4 to 5 weeks of age at the most. This is because a male Syrian’s testicles are very large in relation to its body – almost as large as his head. As a matter of fact, at 5 to 6 weeks old a male Syrian is already capable of fathering children himself. If the hamster is a month or more old and you do not clearly see testicles, Marshmallow is female.
It is much more of a problem to sex dwarf hamsters, because throughout their lives their genitals remain pretty small. You have to judge from the distance between two small openings, the genital opening and the anal opening. It can be tough to see these openings by simply holding your hamster. Instead, put your hamster into a small clear glass and your hamster will likely reach up for the rim, giving you a good view of his or her belly. This online chart shows this distance fairly well.
The male Syrian shown in the chart from the link would be extremely young, probably about 3 weeks at most, because the testicles aren’t prominent at all. Shortly after this stage there isn’t any way to mistake them.