It could be a number of things:
It could be that when she is in standing heat, she desires to be bred and allows a male to mount her.
It could also be that the breeder muzzled and held her while she was mated. Often times breeders muzzle the female, because if a female bites the male, it can be very bad for the stud dog's performance with other bitches.
It can also be that the breeder did an AI. Difficult to breed dogs are often AI'd. You would think a crappy breeder wouldn't want to bother. But even crappier breeders can perform an AI without any help from the vet.
A dog that undernourished though would probably have difficutly in getting pregnant or maintaining a litter. It can also be that she had a false pregnancy.
Jenna, RN CGC & Babs, CD RA CGC HIC
Heidi, RA CGC
SG3 Odessa, SchH1, Kkl1, AD
Ninja, RN CGC & Milla, RN CGC
Joy, Star Puppy, RN CGC
Dolly CGC & Bear CGC
Hepzibah & Hannah