Whipworm

What are whipworms?

Whipworms are intestinal parasites that are about 1/4 inch (6 mm) long. They live in the cecum and colon (large intestine) of dogs where they cause severe irritation to the lining of those organs. Whipworm infection results in watery, bloody diarrhea, weight loss, and general debilitation. They are one of the most pathogenic worms found in dogs.

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How do dogs get whipworms?

Whipworms pass microscopic eggs in the stool. The eggs are very resistant to drying and heat, so they can remain viable (alive) in the environment for up to 5 years. Once laid, they embryonate (mature to an infective stage) in the environment and are able to re-infect the dog in 10-60 days. The embryonated eggs are swallowed and hatch and mature to adults in the lower intestinal tract, completing their life cycle (see illustration).

How are whipworms diagnosed?

To diagnose whipworm infection, a fecal ova and parasite screen will be run.  A small amount (~2grams) of fresh feces (not more than 24 hours old) is needed to run the test.   This sample will be sent to a reference lab which uses a testing process called centrifugal floatation with microscopic examination to look for parasite eggs . This is the most accurate way to get a diagnosis as simple fecal flotations may miss parasite eggs.  However, multiple stool samples are often required because these parasites pass small numbers of eggs on an irregular basis, so some samples may be falsely negative. In addition, it takes approximately 11-12 weeks after hatching for a female adult to begin to lay eggs.  Any dog with chronic large bowel diarrhea should be suspected to have whipworms, even if the stool sample was negative. Thus, it is an accepted practice to treat chronic diarrhea by administering a whipworm dewormer. Response to treatment is an indication that whipworms were present but could not be detected on fecal examination.

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How are whipworms treated?

There are several drugs that are very effective against whipworms. At least two treatments are needed, spaced at a three to four week interval. The most frustrating aspect of whipworm infections is the high rate of re-infection because the eggs are extremely hardy in the environment.  Therefore, if a dog is diagnosed with a whipworm infection, it is advisable to treat again monthly for multiple treatments. The other option, which is much simpler, is to use a heartworm preventative that contains a whipworm medication. Whipworms are not nearly as common today because of widespread use of these modern heartworm prevention products.

How can I best prevent whipworm infection in my dog?

All puppies should be appropriately dewormed as recommended by your veterinarian. The first deworming should be given at two to three weeks of age. Note that this is prior to the time most puppies are seen for first vaccines. Deworming is then repeated every 2 weeks until 12 weeks of age, then monthly until 6 months of age in puppies. It is entirely appropriate to present new puppy for initial examination and deworming only.In addition, prompt deworming should be given if the parasites are detected. Routine deworming of adult dogs is also recommended.  Dosing ranges from monthly during warmer months and periodically during cooler months to year round monthly treatments depending on risk.  Your vet can help you determine the most appropriate deworming program for your dog.

It is also advisable for all dogs to have a fecal examination once to several times a yearly depending on their risk.  This way we can make sure our dewoming programs are working and also pick up other parasites not currently being treated for.

Can I get whipworms from my dog?

No. Whipworms are not infectious to people. They are exclusive parasites of the dog.

This client information sheet is based on material written by: Ernest Ward, DVM (modified by MAH Jan/ 2016)

© Copyright 2009 Lifelearn Inc. Used and/or modified with permission under license.

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