There are several types of worms that dogs can get. If what you are seeing is little white rice type things those are not actually worms but the larvae of worms. A lot of dogs get them - both Amy's Spot and our Jack and Snoopy had worms when we got them. In fact, as I think back on it, Taggert had been treated for worms when we got him and we had to give him the second dose and then have his stool checked.

There is several types of worms and your vet can tell you what type he has and where or how he might have gotten them. But as others has said it is nothing to worry about - just some medicine and all will be well.