Canine Tapeworms

Filed Under: Dogs, Parasites

Two types of tapeworm affect dogs, Dipylidium caninum and Taenia species. Dipylidium caninum is the more common type of tapeworm found in dogs and cats. Adult tapeworms are found in the small intestine of their host. These worms shed small segments, called proglottids (packets of 20 to 40 eggs) in the stool. Once in the environment, proglottids of the Dipylidium tapeworm are consumed by flea larvae. As the flea larva matures, the egg of the tapeworm eventually develops into its infective form called a cysticercoid. The dog or cat ingests the flea while grooming itself. The cysticercoid then emerges in the animal’s small intestine. The cysticercoid in turn attatches to the small intestine developing into the adult worm. The prevalence of the Dipylidium tapeworm depends on the flea population in a particular area.

Dipylidium may become zoonotic (capable of causing human infections) if a person ingests a flea containing the cysticercoid. This is occasionally seen in children when pets have a severe flea infestation.

The Taenia species of tapeworm is spread via small mammals rather than fleas. Dogs and cats shed the Taenia proglottids in their feces and other mammals become infected with the tapeworm cysticercoid by ingestion of the eggs. The eggs hatch after being ingested. The tapeworm cysticercoid is released, migrating into the body organs, usually the liver, and forms a fluid-filled larvae. The dog or cat becomes infected by hunting and consuming the liver of an animal containing the larvae. The larva contains the tapeworm which attaches to the intestinal wall of the new host. Dogs most commonly pick up Taenia from infected rabbits or squirrels, while cats obtain it from infected mice.

Proglottids are shed intermittedly. As a result of the intermittent shedding, not every fecal exam will diagnose a tapeworm infection even though adult worms are present in the animal. Often diagnosis is based on a client’s observation of the tapeworm segments. Most people recognize tapeworms as grains of rice on top of a bowel movement or on the coat of the perineal area (area around the anus and vagina). Some people will refer to the proglottids as sesame or cucumber seeds. These proglottids may also be seen inching their way out of the anal area.

Clinical signs may not always be observed. The most commonly seen clinical signs are scooting and pruritis (itching around the anal area). In most instances, the infection is fairly benign and owners just notice the tapeworm segments passing out in the stool. Young puppies or kittens may have fatal infections if worm numbers are large and they become impacted. Tapeworms may be prevented through vigilant flea control and prevention of opportunistic hunting in pets.

Most veterinarians use praziquantel (Drontal® and Droncit® both marketed by Bayer Animal Health), or epsiprantel (Cestex® manufactured by Pfizer Animal Health) to treat tapeworm infections. Due to the importance of environmental control of fleas, retreatment for tapeworms at 3 to 4 week intervals may be necessary.

Verbac has released a new monthly heartworm preventative which includes tapeworm control called IVERHART MAX™. This product may be helpful with severe infestations. A negative heartworm check is required before starting any heartworm program in the dog.

References:

1. Roundtable Discussion. “Tapeworms Overlooked, Underdiagnosed and Undertreated”, Virbac Animal Health. 2006.

Topics: tapeworms

Symptoms: itching

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