According to petMD, veterinarians identify worms in dogs by analyzing stool samples. Few worms can be identified with the unaided eye, and the presence of worm eggs can only be detected with a microscope. This is why a veterinarian asks for a stool sample from your dog.
WebMD states that canine worms can cause a variety of health problems, and petMD lists some of the symptoms to look for, such as diarrhea, weight loss, dry hair, general poor appearance and vomiting. However, some worm infestations cause little to no symptoms. Furthermore, eggs or larvae can remain dormant in the body and only become activated in times of stress or during pregnancy when the infestation is passed to the puppies in utero.
WebMD indicates that the most common types of worms found in dogs are roundworms, hookworms, tapeworms, heartworms, whipworms and ringworms. According to petMD, no single treatment works on all kinds of worms, so each type of worm requires a different kind of deworming solution. Dog owners help their pets to avoid worm infestation by clearing the yard of feces and not allowing the dog to go in the neighborhood park where it may come into contact with another dog's feces that is infected with worm larvae.