We've recently noticed small snail like (no shell, but has stalky eyes) critters in our dogs poo. They're white with a dark back and about 2cm long. I know snails and slugs can feed on dog poo, but we're pretty sure these came out of the dog as it was in a fresh (sloppy..) batch.

We've recently bought another dog that we got from a rescue place on a farm, and he had a bad stomach when he got to us (initially we thought it was just nerves or change of diet, but now we're not so sure).

Any ideas?