Originally Posted by Michelle's-Draco
The cycle is every 7 to 9 months. MMmm they last 3 weeks not all bleeding, One week in no bleeding and 2nd week bleeding. One week out no bleeding this is the time that you breed or most breeders breed. I don't know if it is diffrent on a large dog as this is how it go's on small dogs as we use to breed yorkies.
Actually, every bitch (large or small) is different as to when (# days into their cycle) they are fertile.
Also, the length of the estrus cycle can really vary from bitch to bitch.
Some bitches may cycle every 4 months some every 9 months - again all very dependent on the individual bitch. Cycling more frequently than every 4mos is not normal.