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Recurring Worms


Mark Hale, DVM

1661 E. Mt. Gilead Road

Bolivar, Missouri  65613



Why Does My Pet Keep Having Worms?


            Imagine seeing a rice-sized worm squirming around on your pets' rear. After your words of disgust are said, your thoughts probably turn to how to get rid of it quickly.

            One of the most common parasites I encounter in practice is the tapeworm.  In some pets, they seem to persist or to reoccur soon after treatment.  A look at the life cycles of these disgusting parasites can help explain their prevalence.



            The "worms" that you see on your pet are actually egg packets passed by the adult tapeworm inside the intestine. These eggs must then pass through an intermediate host to mature into infective larvae. The most common intermediate hosts are fleas, rats, mice, and voles. The infected intermediate host must then be eaten by the pet to continue the lifecycle. Because fleas cause skin irritation, pets lick them off and swallow them. Pets with fleas are likely to have significant tapeworm loads. Adult tapeworms can reach a length of up to two feet. Humans can also be affected by some of these tapeworms, which can form "cysts" in other organs such as the liver, lung, or brain.  Children are most likely to contract this parasite, especially if they do not follow proper hygiene principles.



            Tapeworms are diagnosed by seeing the rice-like segments around the tail area or in the stool.  These segments can actually move, or crawl, as if they were an entire worm.  After they dry out, the segments are smaller and brown, resembling a sesame seed. Microscopic examinations, as are done to diagnose other intestinal parasites, are not very accurate for diagnosing tapeworms.  Rarely tapeworms cause anal irritation and scooting behavior. However, this strange-looking behavior is more commonly due to overfilled anal sacs.



            Adult tapeworms can be easily treated with the correct deworming products.  A large majority of general dewormers are not effective against tapeworms.  Use of the correct products at appropriate dosages is necessary. 

            As is evident after examining the life-cycle, proper control of intermediate hosts is necessary.  Flea control is most important, as the pet will commonly ingest the flea when chewing or grooming itself.  Treatment of the environment as well as the animal is usually required.