My mum always said not to give dogs pork - not sure where she got it from. And indeed, our elder dog once stole a packet of pork hotdogs, ate the lot, and was very, very ill afterwards - a serious vet case, we were worried he wasn't going to survive it.
Since then I've kept him well away from pork. But recently I've read lots that says it's OK. The vet sent a leaflet before Christmas of foods bad for/ poisonous for dogs, and pork wasn't on it.
So we've recently tried giving small quantities to our younger dog, and she seems to tolerate it (mind you, she tolerates dead mice, birds, water voles, pheasants, rotting deer legs
).
I will never give it to our elder dog again, though.