Vet Blog

Four types of intestinal parasites are responsible for most worm infestations in dogs: roundworms, hookworms, whipworms, and tapeworms. Puppies most commonly get roundworms and/or hookworms. They usually acquire these parasites from their mother, either while they are still in utero or through drinking milk that contains worm larvae. Parasitized dogs also contaminate soils when they leave behind a pile of feces. Other dogs become infected when they inadvertently ingest parasite eggs from the environment. Hookworm larvae in the soil can also borrow through a dog’s skin and make their way to the intestinal tract. Eating a prey animal (e.g., a rodent) that contains immature parasites is another way that dogs can pick up roundworms.

Whipworms can be a recurring problem for dogs because their eggs can survive in the soil for years after passing out of an infected dog’s body via its stool. Even areas that have not seen a lot of recent dog activity can be heavily contaminated. When a dog inadvertently eats a small amount of contaminated soil (e.g. in the process of grooming itself), the eggs gain access to the dog’s intestinal tract where they hatch and mature into adult whipworms capable of reproducing and completing their lifecycle.

Tapeworms do not simply produce eggs but actually shed entire portions of their body that contain their eggs inside. These body segments are visible to the naked eye, looking like pieces of rice that are often still moving in the fur around a dog’s rectum or on its bedding. When the segments dry out in the environment they release their eggs, which are then eaten by juvenile fleas. When mature, the fleas hop aboard nearby dogs or other animals that, through the process of self-grooming, can eat and digest the infected flea releasing the tapeworm eggs. Once inside a dog’s intestinal tract, the tapeworms start to develop and begin the cycle all over again. Less frequently dogs can pick up other species of tapeworms by eating infected deer, rabbits, or livestock.

Many dog owners are surprised to hear their pet has intestinal parasites because they have not seen worms in the dog’s stool, but dogs rarely shed entire worms in this way. A visit to the veterinarian for a fecal examination is the best way to determine if your dog has worms, and if so, which type of dewormer will most effectively get rid of these unwanted guests.