Tapeworms in Pets

By: Carol S. Hillhouse, DVM, DABVP

TVMA Member
Panhandle, TX

Published January 2015

What are Tapeworms?

Tapeworms are parasites that live in the small intestine of many different species of animals. There are two main groups of tapeworms, but they are all similar in appearance. Except for the head, which attaches to the small intestinal wall with hook-like mouthparts, a tapeworm’s body is made up entirely of small flat segments, known as proglottids, which contain microscopic eggs.

The Two Main Groups of Tapeworms

Dipylidium caninum is the most common type of tapeworm found in dogs and cats in the U.S. and can be found worldwide. The tapeworm segments are passed in the animal’s feces but are not infective at this stage. First, the eggs must be eaten by flea larvaeThe active immature form of an insect, especially one that differs greatly from the adult and forms the stage between egg and pupa, e.g., a caterpillar or grub.. The eggs will hatch and develop into their infective form as the flea larvae mature into adult fleas. The tapeworm can then be transmitted to a new host by swallowing the flea. After the pet eats the flea, the young tapeworm will mature into an adult. The segments are similar in size to a grain of rice and are passed intermittently in the feces. They will dry out once exposed to air and then look like a sesame seed in size and color. Animals do not become immune and are readily re-infected if exposed to fleas.

Taenia spp. is a second type of tapeworm that is especially common in pets that come from a rural setting, where they may hunt and eat rabbits and mice carrying the larval form. Like the Dipylidium, re-exposure leads to reinfection, and unless their habits can be curtailed, the tapeworms will return as quickly as two weeks after treatment. Both types of worms may survive in the gut for several years, shedding segments intermittently.

What Happens When a Pet has Tapeworms?

The irritation resulting from the peri-anal movements of the tapeworm segments sometimes leads animals to rub or lick their hindquarters excessively and to a socially unacceptable degree. Scooting, another behavioral issue that owners may attribute to tapeworms, is more likely to be caused by impaction of the anal sacs than tapeworm infection. Most often, tapeworms are diagnosed by the detection of segments passed in or on fresh feces. The type of tapeworm can be identified by examining the eggs using a microscope, but this is rarely needed. Fortunately, the medications that kill tapeworms are effective against both types. It is a simple, safe and effective prescription medication available in a variety of forms. Currently, it is not available over-the-counter and must be obtained from a licensed veterinarian and dosed based on the pet’s weight. The treatment will kill the tapeworms already infecting the pet, but unless contact with the intermediate host is eliminated, reinfection will occur.

As previously mentioned, infection with Dipylidium is indicative of the presence of flea infestation. Treatment for elimination of tapeworms must be done in conjunction with flea control, both on the pet and in the environment. Recurrent tapeworm infections are almost always due to reinfection from fleas and not product failure. To avoid tapeworm infection, do not allow pets to hunt or scavenge other animals or ingest raw game, ensure that all meat products are properly cooked and pick up feces promptly. Humans cannot get tapeworms directly from a pet, since the infection depends on an intermediate host. A person must swallow a flea to become infected. A few cases have been reported in children; nonetheless, the risk is very low.

Fortunately, health problems attributable to tapeworms in pets are for the most part very mild. The commonly occurring tapeworms of dogs and cats in this country are not regarded as serious pathogens. Nevertheless, from a practical perspective, they are significant because of their effects upon owners. The passage of active, squirming segments is unsightly and repulsive!

Dr. Carol Hillhouse owns two mixed animal practices in the Texas Panhandle: Carson County Veterinary Clinic and High Plains Animal Hospital.