How old is the puppy?  You should take him to a vet within 3 days of adopting this pup.  Also, unless he is at least 16 weeks old he still needs vaccines.

Get him to your vet for a health check ASAP!

Being a “runt” indicates he is smaller than the other puppies in the litter.  This can mean nothing, or it can mean that he was born with a problem that impacted his ability to take in food and use it properly.  Only a vet can check your pup to make sure he is healthy, and make recommendations about feeding, tests he might need, and shots to prevent diseases that would put his life at risk.

Don’t take the breeder’s word for this – you will fall in love with the pup and may have very expensive vet bills ahead of you if he was born with major problems.  

So, off to the vet — you may feel so much better once you know one way or the other.

Thank you so much for your advise.. I found someone who can get him the help he needs.

Any time he moves his head he yelps loud and I feel HORRIBLE for poor lil guy! I got him wrapped up and holding him trying to get some baby formula into him but not having much luck! Could b a bee sting since I had them out in backyard for first time today but I was with them the hole time, for like a half hr, or maybe momma stepped on his neck accidentally!?!? I dunno but I feel helpless an he’s in pain, almost like party listed!!

i took him to the vet and she said he had strangles, drained the large lump on his neck below his ear and gave us medicine, but now the lump is TWICE the size, he is having trouble breathing, keeps sneezing, coughing, weak, im so scared he cant breath and he is gonnadie, he’s only 4 weeks old. of course its sunday nite and there is no vet open…..