Sorry but that is the wrong answer, round worms are of course round and they come out in large groups, they would look like a moving pile of spaghetti, not just one solitary worm, your dog has a Tapeworm and what you are seeing is probably just a section of the actual worm inside him.
I disagree if it is tape worms because tape worm are thick white round and big even if it IS take it to the vet ASAP it is VERY serious if your dog has tape worms it may require surgery but if it isn't how it looks as I said it is probably hook worms (a flat round white invisible looking kind of worm) either way take your dog to the vet ASAP!!!
He has a round Warm. You can just go to a petstore to get pills to treat it, and its very affective soo don't bother spending a lot of moneyy to take him to a vet. Just go to the pet store and ask for small dog round worm medication, they should be pills.
Its a tape worm, give it safe guard and a lil ivomec
It is a tape worm get some medication for it ASAP before they actually give it surgery, talk to a vet first :P!
If it is like my doberman it is flat worms not round or tape worms your vet should have a shot to help get rid of them