Some people make the mistake of bringing a female back out too soon after welping a litter. They don't realize that when a bitch gets pregnant, her body softened up and is not the same as before. It's almost like starting all over again. She needs months nd months of exercise just to get her body back into shape. That's when they thought "breeding took a lot out of her" yes it did, but it's your job to bring her back to how she was before and not let her just sit on the chain until you contract her.