Tapeworms in dogs are Dipylidium caninum, Taenia pisiformis and Echinococcus granulosus.
Tapeworms in cats are Dipylidium caninum and Taenia taeniaformis.
Let’s begin with the tapeworms you are most likely to deal with in your pet, Dipylidium caninum or D. caninum. As with many parasites, the life cycle of D. caninum is complex and includes an intermediate host. The intermediate host for D. caninum is the common cat or dog flea. The life cycle goes like this: a flea carrying an immature stage of D. caninum jumps on a dog or cat for a blood meal. The pet swallows the flea during routine grooming. The flea, of course, dies in the intestinal tract, but, if sufficient time has passed for the immature D. caninum to mature to the next stage, the tapeworm then finishes maturation and attaches itself to the intestinal wall. A little more time passes and the tapeworm begins efforts to reproduce itself by passing proglottids, or segments, which are packets of eggs to infect more fleas to repeat the cycle.
This is a parasite that we rely on pet owners to report to us. The fecal flotation works by finding the eggs of parasites in the stool. D. caninum eggs, however, are sealed inside the proglottids. So, unless a proglottid ruptures and spills its eggs, no D. caninum eggs will show up on the fecal flotation. How does a pet owner know that his pet has tapeworms so that he can report them to us? You will see small worm-like proglottids in or on the stool, or on the hair around the anus. When fresh they are about 3/8″ long, white to off-white, flat, and crawl around like inch-worms. After drying they turn light to medium tan and look like grains of brown rice.
If you see tapeworm segments your pet’s doctor can give an injection or dispense tablets to treat the infestation. The treatment is almost 100% effective, however, it is not a preventive, so if your pet swallows a tapeworm-carrying flea he will get tapeworms over again. Therefore, prevention for tapeworms is maintaining a high level of flea control.
Taenia pisiformis’ life cycle is very similar, except that they utilize lagomorphs (rabbits) and rodents (squirrels, rats, mice) as intermediate hosts. Pets are most commonly infected when they hunt, but catching such small creatures or by eating the offal of rabbits and squirrels when hunters field-dress their kill. Proglottids are passed as with Dipylidium caninum, and the physical appearance of the two types of segments are indistinguishable by pet owners. The same medications that kill D. caninum will kill T. pisiformis. Prevention involves keeping your pet from hunting rodents and rabbits and for hunters to separate their dogs from the area where they field-dress their game.
Echinococcus granulosus is a tapeworm parasite of dogs, wolves and foxes that can infect people who come in contact with canid feces in which the eggs are shed. The definitive host canids are not adversely affected by the parasite, but it can cause devastating disease in people.
As always, if you come in contact with your pet’s stool, wash your hands thoroughly with soap and hot water.