Tapeworms live in the small intestines and vary from less than an inch to several feet in length. The head of the worm fastens to the wall of the gut by hooks and suckers. The body is composed of segments that contain the egg packets. To cure tapeworm infection, the head must be destroyed. If it is not, the worm will regenerate.
The body segments containing the eggs are passed in the feces. Fresh, moist segments are about one-quarter inch (6 mm) long and are capable of moving. Occasionally you may see them crawling through the fur near your dog’s anus. When dry, they resemble kernels of rice. Some dogs experience anal itching from the segments. Tapeworms will drain nutrition from your dog but not to the extent that ascarids, hookworms, and whipworms will.
The common tapeworm of dogs is Dipylidium caninum. Fleas and lice serve as intermediate hosts when they ingest the eggs. A dog must bite or swallow an infected flea or louse to acquire the parasite. A human could also acquire D. caninum if they accidentally swallow an infected flea.
Several species of Taenia, another type of tapeworm, parasitize dogs. Taenia are acquired by eating infected rodents, rabbits, and sheep. Diphyllobothrium species are found encysted in the organs of fish. These tapeworms are found in the northern United States and Canada.
Echinococcus tapeworms are uncommon in dogs. Intermediate hosts are deer, elk, goats, sheep, cattle, swine, horses, and some rodents.
Treatment: Droncit, Cestex, Drontal Plus, Telmintic, and Vercom Paste are highly effective against all the common dog tapeworms. Use them under veterinary guidance.
Prevention: The common dog tapeworm can be controlled by eliminating fleas and lice from the environment, as described in Disinfecting the Premises. Dogs should be confined to prevent them from roaming and eating dead animals. Avoid feeding your dog uncooked meat and raw game.
Public health considerations: Echinococcus granulosa and Echinococcus multiocularis are significant public health problems. Dogs and humans can acquire the infection from eating contaminated uncooked meat, and, in the case of dogs, by feeding on the carcass of an infected animal. Humans can also acquire the disease by ingesting eggs passed in the feces of dogs. Since humans are not the definitive host, adult worms do not develop. Instead, the larvae produce large cysts in the liver, lungs, and brain. These cysts are called hydatids, and they can cause serious illness and even death.
Echinococcus granulosus is found in the southern, western, and southwestern United States – areas where sheep and cattle are common. Although dog-to-human transmission is rare, a number of human cases (presumably from eating uncooked meat) are reported each year. If your dog runs free in a rural area where this tapeworm could be a problem, ask your veterinarian to check her stool for tapeworms twice a year. This species of tapeworm can be identified only after the head has been recovered by effective deworming. Until a definite diagnosis is made, a dog with a tapeworm that could be Echinococcus must be handled with extreme care to avoid fecal contamination of hands and food.