Whipworm Infection in Cats

What are whipworms?

Whipworms are intestinal parasites that are about 1/4 inch (6 mm) long. They live in the cecum (a pouch that forms the first part of the large intestine) and large intestine of cats, where they cause severe irritation to the lining of those organs. Large infestations of whipworm can cause watery diarrhea, weight loss, and general debilitation. 

Whipworm infection in cats was rare in North America, but cases appear to be rising. Infection is more common in tropical and subtropical areas.

How do cats get whipworms?

Whipworms pass microscopic eggs in the stool. The eggs are very resistant to drying and heat, and they can remain alive in the environment for up to five years. Once laid, they mature to an infective stage (a process known as embryonation) in the environment and can infect another cat in 14–21 days.

The mature eggs are swallowed by the cat, then hatch and mature into adults in the lower intestinal tract, completing their life cycle.

How are whipworms diagnosed?

Whipworms are diagnosed by finding eggs on microscopic examination of the stool. These eggs, however, are difficult to find. Whipworms pass small numbers of eggs on an inconsistent basis; therefore, some samples may be falsely negative. Multiple stool samples are often required to diagnose a whipworm infection. 

Additionally, it takes approximately 11–12 weeks after hatching before a female adult begins to lay eggs, so tests run too early after infection are often falsely negative. Newer testing that looks for whipworm DNA in the feces is more effective, but there are still false negatives.

How are whipworms treated?

There are several drugs that are effective against whipworms, including fenbendazole (Panacur®), milbemycin oxime (Interceptor®), moxidectin + imidacloprid (Advantage Multi®), and emodepside + praziquantel (Profender®). All drugs require repeated treatments that are spaced at appropriate intervals to clear the infection.

The most frustrating aspect of whipworm infections is the high rate of re-infection, since whipworm eggs are extremely hardy in the environment. Therefore, if a cat is diagnosed with a whipworm infection, it is advisable to treat it again every three to four months. A simpler option is to use a heartworm and flea preventative that contains a whipworm preventive.

Can I get whipworms from my cat?

Whipworms will not infest humans as they do cats and transmission is very unlikely, although there have been rare cases of abnormal whipworm infection in people.