A Guide to Preventing Canine Worms

Canine worms are a range of species of parasitic worms that infest the body of a living dog. The most common varieties of canine worms infest a dog's digestive system, especially the intestines. While all canine worms are extremely uncomfortable for the infected dog, the majority will affect the dog slowly, giving you plenty of time to treat the problem. However, some canine worm species can be fatal in small dogs or puppies if left untreated, so it is very important to be informed about canine worms and how to deal with them. The most common types of parasitic worm species to infect domestic dogs are tapeworms and roundworms.


Tapeworms begin their lifecycle inside fleas, so your dog is most likely to contract tapeworms if it is infested with fleas, and it unknowingly ingests fleas when it bites at a fleabite to scratch it, or when it eats a small animal that is infested with fleas. The tapeworm larvae then mature in the dog's small intestine, surviving by consuming nutrients that the dog has eaten. Tapeworm infestations are not usually a very serious problem because they are easily detected, but since they consume nutrients that the dog would otherwise absorb, small canines can die of starvation if a tapeworm population is too large inside their bodies.


Roundworms rarely infest adult dogs, but are common in puppies. Roundworm populations can grow so large in puppies that the animal actually appears inflated at the gut. Female roundworms in a canine intestine can produce up to two hundred thousand microscopic eggs every day. These eggs are protected by a hard shell, so they can lay dormant for years in soil that at one time contained an infected dog's feces.

Dogs become infected with roundworms when they unknowingly ingest the eggs contained in other dog's feces, or when they eat something with dirt on it that once contained the feces of an infected dog. The eggs then hatch in the intestine and become microscopic roundworm larvae. Then, entering into a bizarre phase of its lifecycle, the roundworm larvae burrows through the intestine wall, travels to the lungs through the blood stream, and comes out from the windpipe through the lungs. By this time, the larva has grown large enough for the puppy to gag or choke on, and if the dog is very lucky, it will cough up the larva, but it is far more common for the roundworm larva to quickly force its way back down the puppy's throat, through the stomach, and back into the intestine, where it matures to an adult roundworm. Adults can grow up to seven inches long.

Detection and Treatment

The best way to check for tapeworms is to look for small, rice-like segments of the worms that may appear in the dog's feces or stuck in the hair around its anus. The only medication that works to remove tapeworms is Droncit. Roundworm infestations can be killed off using over the counter medications, but it is advisable to consult a veterinarian, because de-worming drugs are poisonous to small dogs if used improperly.