When Do Female Puppies Come In Heat. I know this sounds very early, but this is actually the age. On average, female dogs go in heat starting when they are around 6 months old.
The proestrus stage (lasts for about 9 days) and is the first stage of the heat cycle. Will go through formal rituals of sniffing, marking, tail wagging, and posturing. I know this sounds very early, but this is actually the age.