Should you choose a male hamster or a female hamster? According to "Training Your Pet Hamster" (Gerry Buscis & Barbara Somerville, 2002), there is very little difference in between keeping male or female hamsters as pets. Both sexes have roughly the same temperament, no matter which of the several pet hamster species on the market is chosen.
No matter what the species of pet hamster, the females are always larger than the males. This size differentiation is best seen in the largest pet hamster species, the Syrian or golden. Male hamsters have very large testicles in proportion to the rest of their bodies. Hilltop Animal Hospital reports that many male hamster owners mistakenly think their pets have grown tumors, when they are just testicles.
Male hamsters often smell stronger than a female. This is due to body odor from a scent gland called hip spots or flank glands. Females have these glands, too, but they are smaller than in males. When the male licks the glands, the musky odor is produced. Syrian hamsters have two glands while dwarf hamsters only have one.
The scent glands secrete oil, which helps the male hamster mark his territory. However, it can also make him look greasy or dirty. Sometimes hair around the scent glands may grow longer than anywhere else on the body. Scent glands are often hairless in dwarf hamsters, so they may be mistaken for tumors.
"Training Your Pet Hamster" also points out that male hamsters over the age of 2 often become less active and then become prone to obesity. Obesity can predispose a male hamster to heart conditions, infertility and diabetes. The species most prone to diabetes is the Campbell's dwarf hamster.
It is possible to get a male hamster neutered. This is often the only way to combat testicular tumors. However, any surgery on hamsters is risky because of complications with anesthesia. Finding a vet experienced enough to do a hamster castration operation may also be difficult.