My 13yr old basset hound was run over in the snow, vet said no broken bones, but I am worried about internal damage, what should I look for?

Vet do scams on the dog, the vet did not give you a list of things to watch for ? No offense, if my vet did not tell me all of that, at a visit, I would be looking for a new vet.

But blood of any kind is one sign, not eating, change in habits or mood.

Blood in the stool, projectile vomiting, blood in the vomit, lethargy, pain when moving, pain when laying still, bloating of the belly, etc. etc. etc.

This is really something the vet should have discussed with you.

I definitely would have asked for the results of X-rays and an ultrasound. Did you ask the vet about the types of testing your dog had done ?