Plenty of animals mate for life and form unbreakable bonds with their sexual partners, but dogs do not. Canines are biologically wired to mate often and with a variety of partners, the males especially so. They are not particularly discriminating when it comes to choosing mates. While females go into heat only twice a year, males may mate with any in-season partner year-round.
According to a report by Dr. Daniel Estep and Dr. Suzanne Hetts in the "Rocky Mountain News," dogs are promiscuous creatures. Rather than forming a bond after mating, dogs move on to other partners. Males are even more promiscuous than females, roaming the neighborhood marking territory to advertise their virility to any willing partners. Females do the same, though they do so more frequently when they are going through their twice-annual estrus.