Newborn Puppy can't Nurse
My chihuahua gave birth yesterday morning to a very tiny purebred boy. Immediately puppy wouldn't stop crying and mamma was getting frantic. I soon realized puppy was crying with his mouth closed and couldn't find nipple.
Since then I have expressed milk and, through much manipulation, pried open his tiny mouth and gotten him on it but even after he successfully nurses once the next time he won't open his mouth again.
New born puppies should nurse instinctively but occasionally there is a problem and it sounds as though this little guy is having big difficulties.
I'd strongly recommend that you get him examined by your veterinarian right away to make sure that he's otherwise healthy and that there's no physical reason for him to be having difficulty opening his mouth.
If he gets a clean bill of health, then it's going to be up to you to help him get the nutrition he needs as he's having so many problems nursing.
It may be that you'll need to tube feed him because that doesn't involve him having to suck, and is quicker than trying to bottle feed a puppy who's fighting it.
However, it can be tricky and there's an element of risk so you'll need to be shown how to tube feed by your veterinarian, and also get the correct equipment.
Tiny puppies need a lot of nutrition and this little one is at risk of dehydration if he's not drinking enough. That can lead to him getting chilled, organ failure, even death.. and it can happen very quickly.
SO please get your vet on board to help you asap so that this puppy has a fighting chance.
I wish you lots of luck and hope that you're successful in feeding him so that he grows and thrives.