What are whipworms?
Whipworms are intestinal parasites that are about 1/4 inch (6 mm) long. They live in a cat’s large intestine and cecum (a pouch that forms the first part of the large intestine), where they cause severe irritation to the intestinal lining. Whipworm infection in cats is very uncommon in North America. The dog whipworm, Trichuris vulpis, rarely affects cats. Infection is more common in tropical and subtropical areas and may be due to different species of Trichuris.
How do cats get whipworms?
Whipworms pass microscopic eggs in the stool. The eggs are resistant to drying and heat, and they can remain alive in the environment for up to five years. Once laid, the eggs mature to an infective stage (a process known as embryonation) in the environment and can infect another cat in 14 to 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.
What are the signs of whipworms?
Large infestations of whipworm can cause watery diarrhea, weight loss, and general debilitation. Smaller infestations are likely to be asymptomatic.
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, so some samples may be falsely negative. Multiple stool samples are often required to diagnose a whipworm infection.
Additionally, it takes approximately 11 to 12 weeks after hatching before a female adult begins to lay eggs, so tests run soon after infection are often falsely negative. Newer testing looks for whipworm DNA in the feces, and while it is more effective, there are still false negatives.
How are whipworms treated?
Several medications are effective against whipworms in dogs, although they are off label for whipworms in cats. Many drugs are commonly prescribed for off-label use in veterinary medicine. “Off label” means the drug is being used in a way that has not been reviewed or approved by the U.S. Food and Drug Administration (FDA) or Health Canada.
Medications used for whipworms include fenbendazole (Panacur®, Safeguard®), milbemycin oxime (Interceptor®, Milbemax®), and moxidectin + imidacloprid (Advantage Multi®). All drugs require repeated treatments, spaced at appropriate intervals, to clear the infection.
The most frustrating part of whipworm infection is the high rate of re-infection, since whipworm eggs are extremely hardy in the environment. For that reason, 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 is effective against whipworms. Your veterinarian will advise you on the best treatment option for your cat.
Can I get whipworms from my cat?
Whipworms are species-specific parasites and do not infest humans as they do cats and dogs. Transmission to humans is unlikely, although there have been rare cases of abnormal whipworm infection in people. The best prevention is prompt, hygienic removal of pet feces and regular deworming of all pets.
