Female American Staffordshire Terriers (Pit Bull Terriers) come into season once every six months and it lasts for 10-14 days.
She will clearly show you when she is ready and in heat.
A Yorkshire terrier are usually in heat for 6 weeks, the 2 week, is the best to breed because she is fertilized. And the discharges have gone through allot already!
Check with your vet. Usually female dogs go through a heat cycle, called estrus, every six months or twice a year. This heat cycle lasts for several days up to three or four weeks.
The average heat cycle is three weeks or 21-days. In some dogs, it lasts only two weeks while others go four weeks.
From the second heat.
Vets will spay a dog while they are in heat but it is typically more expensive then when they are not in heat.
By her 2nd heat.
what controls the heat pump to determine whether it is in the heating cycle or cooling cycle
Usually between six months and a year old, but it is different for each dog.
All dogs are different. The heat cycle is three stages, coming in, in, and going out. The stages can last 3-7 days each, which means the whole cycle can be 9-21 days. They can get pregnant all through the cycle but are the most fertile and receptive in the middle stage. Our Australian terrier female usually ran the cycle for about 5 or 6 days each stage.
what controls the heat pump to determine whether it is in the heating cycle or cooling cycle
By the 2nd heat or after.