puppy not growing
i have a litter of boxer puppies and the runt is eating but does not seem to be growing
A runt is sometimes small just because of his placement in the womb, or an extra-large litter etc., but other times he's small because he has underlying health issues.
I'd recommend that you have this little guy examined by your vet to make sure that he's healthy and that there's no physical reason why he doesn't seem to be growing.
If your vet pronounces him healthy, then it will probably just be a case of giving it time. Some litters of new born puppies contain runts remain the smallest in the litter, others end up outgrowing their siblings. As long as he's healthy and eating normally he will fulfill his own, individual size potential eventually.
Hope this helps. Best of luck with your litter.