how long do dogs stay in heat.
Dogs can go into heat as young as four months in smaller breeds, but averages about six months old. Some giant breeds may not go into their first heat until theyâre 18-24 months old. It is strongly advised not to breed young female dogs during their first and second cycle.nce it does, the average is about every six months. Smaller breeds may go into heat more frequently, as often as 3-4 times a year. Larger dogs, like Irish Wolfhounds, St. Bernards and Great Danes may only go into heat every 12-18 months.