Puppy can't breathe

Hi

I was wondering if anyone can, Tootsie who is a Jack Russell had 6 puppies 8 days ago (this is her first litter) and all seemed fine. They were all feeding ok and putting on weight nicely, we spoke with the vet who didn't seem to think there was any reason to visit.

Yesterday one puppy seemed to be drinking less than the rest, she was the first born but the smallest of the litter and the others seem to be pushing her out of the way a bit. Today she seems unable to breathe and constantly has her mouth open. I have fed her with lactol milk as I initially thought she may just be weak from not feeding as much.

I plan to take her to the vet tomorrow but just wondered if anyone had any advice for today

Many thanks

Tracey