How do you know if a dog has worms?

There are eleven common symptoms of worms in dogs, according to Cesar's Way magazine. These include vomiting, coughing, diarrhea, lethargy, pot belly, change in appetite, weight loss, dog scooting its butt on the ground and worms in the dog's feces.

If a dog owner suspects his pet has worms, the dog needs to be seen by a veterinarian for evaluation. PetMD recommends taking a fresh stool sample to the appointment so the vet can perform all necessary tests. There are several types of parasites that infect dogs, and the vet needs to determine which parasite the dog has to prescribe the correct treatment.