The Stuff You HAVE to Know
About How Frequently
This Breeder is Having Litters
How often do you have puppies available?
If someone must breed, one litter every 3 years would probably be plenty. After all, if they are keeping a puppy from every litter, how many dogs can they comfortably live with and insure high quality of life? With that said, there are alot of breeders that are responsible in every other way that are producing a litter a year. More than that becomes very questionable and probably an indication of shortsightedness and/or greed on the part of the breeder.
However, depending on the honesty of the breeder this gets more and more murky as many breeders co-own dogs with others. As these dogs are bred, they are also listed as the breeder even though the dogs are not in their home. So yes, be sure to ask if they co-own any dogs that are bred. If they own males you might even ask how often their males are bred (since those litters would belong to other breeders). Someone who is responsible for producing LOTS of dogs is still producing LOTS of dogs and clearly there is only one real reason for that.
A stud dog that is used alot may be a top winning dog with great popularity or may be in the hands of someone who is willing to breed to any bitch for a 'puppy back' which they can then sell or breed themselves.
Of course any additional questions you might have on this topic will be enthusiastically fielded at DigitalDog's Forum .