Going to view a puppy tomorrow and both parents and 4 grandparents have amazing results (hip scores all under 10, ALL elbows 0, clear eye tests and clear DNA results. Will a runt still exist in this litter, or will there just be 1 smaller than the rest (last one out the womb) but they all grow to normal size and weight etc?
As far as I'm aware, runts can occasionally be born in any litter, no matter how well bred the parents are. If you are concerned about the size of one of the puppies then this article might be of interest: https://thehappypuppysite.com/runt-of-the-litter/
The size of a puppy has little to no bearing on the size of adult dog they will become. Many puppies were the smallest in their litter and turn out to be the same size as the rest. The size of a puppy also has no bearing on who was 'last out' the uterus - it is to do with where the puppy attaches in the uterus and the quality of the nutrition which their own placenta receives. Just as if you plant a plant in poor soil, it will not grow as well as a plant in rich and nutritious soil... so the site of the placenta affects the size of the pup. But such pups typically rapidly develop as normal after birth and make up for lost time.... There is not always a runt in a litter. Pups may be roughly around the same weight and size. A true 'runt' is actually not that common, more often there is just a pup which is slightly smaller than the rest. I would be wary of homing a true runt which is substantially smaller than the other pups in the litter, as it can be a sign that there is something else wrong internally - which may not be diagnosed yet. And sometimes they are just a small pup. But you can't know, in advance.
My 2nd lab was called "the runt" but he grew to be a big boy and had a great healthy 12 years The puppy we have now was the smallest of the litter at the time that we chose her (thats not why we chose her). She was middle of the pack during a visit two weeks later and a week after that on their last visit with their breeder vet she was the largest at 8 weeks. To me at this point, at almost 6 months old, she seems very average in size. Just thought I would share our experience
