When does a female dog have her first estrous (heat) cycle?
Dogs will have their first estrous (reproductive or heat) cycle when they reach puberty. Each cycle consists of several stages; the stage called estrus refers to when the female can become pregnant. Often a dog that is in the estrus stage is said to be in heat or in season.
“A dog that is in the estrus stage is said to be in heat or in season.”
On average, puberty (or sexual maturity) is reached at about six months of age, but this can vary by breed. Smaller breeds tend to have their first estrous cycle at an earlier age, while large and giant breeds may not come into heat for the first time until they reach eighteen months to two years of age.
How often does a female dog come into heat?
Most dogs come into heat twice per year, or about every six months, although the interval can vary between breeds and from dog to dog. Small breed dogs may cycle three times per year, while giant breed dogs may only cycle once every 12 months. When young dogs first begin to cycle, it is normal for their cycles to be somewhat irregular. It can take up to two years for a female dog to develop regular cycles. There is no time of year that corresponds to a breeding season for (domesticated) dogs except for Basenjis and Tibetan Mastiffs which typically tend to cycle in the spring.