REPRODUCTION IN DOGS
Reproductive Season, Heat, Oestrus, And Pregnancy Tests Puberty or sexual maturity in the female dog usually occurs around six months of age. The smaller breeds tend to go into oestrus or "heat" earlier and some females can have their first "heat" cycle as early as four months of age. On the other hand, the large and giant breeds can be up to two years old before they come into heat for the first time. How Often Do Female Dogs Come Into Heat? On average this occurs about twice a year or every six months, although it varies from dog to dog. When cycling first begins, there may be a great deal of variability in the time between cycles. This is normal. Some females take eighteen months to two years to develop a regular cycle. There is no evidence that irregular heat cycles predispose the dog to false pregnancies or pyometra (uterine infection). Small breeds tend to cycle more regularly than the larger breeds. Three and occasionally four heat cycles per year can be