An issue came up with a new club and their Breeder's COE as it states that dogs can have two back to back litters, then must rest for one. When confronted one of the board members posted this:
There are two types of female dogs those used ACTIVELY in a breeding program and those that are fixed. Due to the fact that every time a dog has a heat cycle damage is done to the lining of the uterus. Infection in the lining of the uterus is established as a result of hormonal changes. Following estrus ("heat"), progesterone levels remain elevated for 8-10 weeks and thicken the lining of the uterus in preparation for pregnancy. If pregnancy does not occur for a few estrus cycles, the lining continues to increase in thickness until cysts form within it. The thickened, cystic lining secretes fluids that create an ideal environment in which bacteria can grow. Additionally, high progesterone levels inhibit the ability of the muscles in the wall of the uterus to contract. The most common factor in missed litters is the condition of the uterus. Changes to the uterus occur because of low grade bacterial infection, and the progesterone stimulation that occurs in the 'false pregnancy' experienced by EVERY non pregnant bitch following her heat. Progesterone causes changes in the uterine lining and additionally lowers resistance to bacterial infections. A study was done by IAMS over the past several years with over 7000 females and 17,500 litters. It shows breeding every heat cycle (on average a female cycles every 6-10 months) is far healthier for the female dog and the puppies too.
Have at it!!! I'll check back in when I get home from work. I'm expecting links so I can debunk this. PBT DON'T FAIL ME NOW!!