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March 23, 2017 – The intestinal parasite Tritrichomonas foetus has been around for a long time, but veterinarians used to think it only caused problems in cattle. Recently, the parasite was recognized as a major cause of diarrhea in cats. Your cat may be infected with this parasite and you might not even know it!

“It is important that cat owners are well informed about Tritrichomonas species infection because it is common,” said Dr. Jody Gookin, an expert on Tritrichomonas species infections of cats and new member of Morris Animal Foundation’s Small Animal Advisory Board. “The organism spreads easily from cat to cat, causes lifelong infection, and in many cases is incurable.”

T. foetus is more common in young cats living in high-density environments such as shelters where the parasite is easily transmitted. Some cats, especially older ones, may have no signs of illness at all but can be a source of infection for more susceptible cats in the same household or shelter.

The most common sign of T. foetus infection is loose stool. This type of large-intestine diarrhea can be uncomfortable, and cats will sometimes jump in and out of the litterbox. The loose stools caused by T. foetus can come and go, making diagnosis tricky. And, unlike other intestinal parasites, T. foetus doesn’t usually cause weight loss, poor hair coats, or other signs we typically associate with sick cats.

Veterinarians use one of three tests to diagnose Tritrichomonas infections:

  • Microscopic examination of stool sample (direct smear)
  • Stool culture
  • Polymerase chain reaction test on stool

The direct smear is an easy and inexpensive test, but it is the least sensitive at detecting infection. Stool cultures can be done by your family veterinarian but require a special culture pouch. Polymerase chain reaction test is the most sensitive test but also is the most expensive, and usually needs to be sent to an outside laboratory.

Treatment options for T. foetus are currently limited to one medication, ronidazole. Ronidazole is usually effective in treating T. foetus infections, but it can have side effects and treatment must be done under close supervision of a veterinarian.

Many, but not all, T. foetus infections eventually resolve spontaneously without specific treatment. However, diarrhea can take several months to as long as two years to completely disappear. And some apparently “recovered” cats can become long-term carriers of T. foetus, spreading the disease to vulnerable individuals.

Veterinarians agree they need a better way to treat T. foetus infections. Three recent, interconnected Morris Animal Foundation-funded studies, including Dr. Gookin’s research, responded to this need by looking for new approaches to treat this parasite. Dr. Gookin is one of several Foundation-funded researchers interested in learning more about this organism.

The studies initially focused on learning how T. foetus attaches to the lining of the intestine. Once the researchers learned this, they started looking for ways to block this attachment. Researchers identified three compounds that look promising as future treatments for T. foetus infection. Work is in the final stages, but researchers are optimistic they have discovered a new treatment option for T. foetus infections.

Understanding the signs of disease can help you identify if T. foetus could be affecting your cat, and guide you and your veterinarian to the best treatment strategy. Although T. foetus can cause serious diarrhea in cats, the good news is that Morris Animal Foundation-funded researchers are on their way to finding a better way to treat this disease. You can learn more about current Morris Animal Foundation research studies by visiting Our Work.