Just something to think about, although it is a common thought that breeding back to back is "wrong" or something puppy millers do, the advice that breeders are getting now from Repro Specialists IS to breed females back to back and retire earlier. The thoughts are that the female is healthier when she's younger, and a heat has a hormonal effect on the body regardless of whether the female is bred or not, so the only REAL rest for a female is for her to be spayed. Therefore, if the female is healthy and bounces back from a litter well, it is being advised now that she should be bred back to back and retired by 4-6 years. There are SEVERAL articles out there concerning this new research and knowledge, but here is just one of them that I found quickly:
http://www.traumhofgsd.com/The%20Deb...0a%20Bitch.pdf