Male or Female?
When it comes to gender, most people want female dogs. They have a reputation for being easier to handle and “cleaner” as far as not marking in the house. Pugs can have differences between the sexes, however, so don't automatically rule out one over the other. Males tend to be cuddlier, while females can be aloof and tend to make better watchdogs. Males also have a tendency to be calmer, although there are always exceptions. A pug of either sex is cheerful, amusing, mischievous, and sensitive.
Naturally, there are physical differences as well. Unless a female is spayed, she'll go into season (heat, or estrus) for about three weeks, twice a year. This usually occurs every five to seven months. A bitch (female) in season has swollen genitals, which she licks frequently, and a bloody discharge that can be light or heavy. During this hormone-driven period, your pug may enthusiastically hump anything or anyone she can find. Without careful supervision, she'll become an escape artist in search of any male — pug or not — to satisfy her urges.
Males and females have different elimination habits. Males will lift their legs on almost anything, from your freshly painted fence to a wall or sofa. Females generally squat neatly, although it's not unheard of for a dominant female to lift her leg.
In both sexes, spaying or neutering can reduce or eliminate these unpleasant behaviors. Spay/neuter surgery also has health advantages. Spaying prevents uterine infections. If a bitch is spayed before her first heat, her risk of developing breast cancer later in life is reduced significantly. Spayed females are also spared the hormonal disruption of a false pregnancy, in which the uterus swells and the nipples engorge with milk. This can be disturbing to the dog both emotionally and physically.
Neutered males are protected from testicular cancer, prostate disease, and perianal adenomas, growths around the anus that are testosterone-dependent. Neutered males are also less likely to lick their genitals, lift their legs, or hump guests. Nor do they have any reason to roam in search of a willing and able female. Because neutered animals of both sexes have no desire to reproduce, they can focus all their love and attention on their people.