Dog reproduction

Dog reproduction

Unlike undomesticated canine species, where the females typically come into estrus (also called in season or in heat) once a year, usually in late winter, and bear one litter of young, the female of the domestic dog can come into season at any time of the year and usually twice a year. Most bitches come into season for the first time between 6 and 12 months, although some larger breeds delay until as late as 2 years. Like most mammals, the age that a bitch first comes into season is mostly a function of her current body weight as a proportion of her body weight when fully mature rather than age, with the different maturation rates of the various sizes of dogs accounting for this variation in age of first season. The amount of time between cycles varies greatly among different dogs, but a given dog's cycle tends to be consistent through her life.

Dogs bear their litters roughly 9 weeks after insemination.

Catahoula Leopard Dog nursing litter of puppiesAn average litter consists of about six puppies, especially for breeds that have not strayed too far from their wild ancestors. However, litters of many more or only one or two puppies are also common. Some breeds have a tendency to produce very large litters. Since a mother can provide milk for only a few of those puppies, humans must assist in the care and feeding when the litter exceeds eight or so.

Some breeds have been developed to emphasize certain physical traits beyond the point at which they can safely bear litters on their own. For example, the Bulldog often requires artificial insemination and almost always requires cesarean section for giving birth.

Puppies often have characteristics that do not last beyond early puppyhood. For example, eyes are often blue when they first open but change to other colors as the puppy matures. As another example, Kerry Blue Terrier puppies have black coats when they are born and their distinctive "blue" color appears gradually as the puppy nears maturity. The ears of erect-eared breeds such as the German Shepherd Dog are softly folded at birth but straighten as the puppy grows.

Dog experts advise that dogs not intended for further breeding should be spayed or neutered so that they do not have undesired puppies, which are often abandoned or are euthanized due to lack of space and resources in shelters. Abandoned dogs often go feral and form predatory packs that attack livestock and occasionally also prove dangerous to humans. Spaying and neutering can also help prevent diseases such as breast cancer and prostate cancer that occur as the unneutered animal ages (due to hormonal changes). Also, it is not required for a female dog to either experience a heat cycle or have puppies before spaying; likewise, a male dog does not need the experience of mating before neutering. These myths account for numerous health problems and unwanted puppies.

Allan
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