Yes, especially if the dog gets into the cat littler... I would deworm both of them!
If My Cat Has Worms, Can He Give Them To My Dog?
Yes, but some worms are more common in dogs than cats. If you think one or both of them has worms take a fresh stool sample to the vet to be examined along with the dog and/or cat.
My new kitten has worms so can she em' to me and my dog