Female dogs typically go into heat about twice a year, or every six months on average. However, this can vary significantly depending on the dog's breed, size, age, and individual factors. Small breeds often have heat cycles more frequently, sometimes up to three times a year, while very large breeds may only go into heat once a year. The first heat usually occurs between 6 to 24 months of age, with smaller breeds experiencing it earlier and larger breeds later. The heat cycle lasts around 2 to 3 weeks, during which the dog is fertile and can mate successfully.
