Piroplasmosis Horses Removed from Quarantine

Two horses positive for equine piroplasmosis were removed from a quarantined stable in Raytown, Mo., Wednesday night, according to reports published in The Kansas City Star and other local news outlets. Five other positive horses were euthanized Thursday with their owners' consent.

The Missouri Department of Agriculture is reported to be working with local officials and the FBI to locate the missing horses.

A foreign animal disease investigation was initiated June 3, according to a report issued to the World Organization for Animal Health (Office International des Epizooties, or OIE) by John Clifford, DVM, deputy administrator of the USDA's Animal and Plant Health Inspection Service. A 7-year-old Quarter Horse gelding was presented to a veterinary hospital in Kansas June 2 for acute illness consistent with infection of a blood-borne pathogen. The horse was placed under quarantine and isolation.

The Raytown Equestrian Park, home to 64 equids, was quarantined June 6, and equine piroplasmosis (Theileria equi) was confirmed in the affected horse June 10.

As of the June 11 OIE report, results of tests on the other equids on the property were pending. Of these, 44 animals were stabled, 18 were on a common pasture, and one was on an isolated pasture.

Equine piroplasmosis is an infectious disease caused by two types of protozoal parasites, which attack the red blood cells. It is characterized by fever, anemia, weight loss, jaundice, and, in some cases, death. The case fatality rate can be up to 20% in naive horses. The only treatment is a potent type of chemotherapy that can have serious side effects in some horses.

The disease is spread by ticks, the use of contaminated needles, and possibly through blood-contaminated semen of infected stallions. Infected ticks pass the parasite while feeding.

The United States has screened all imported horses for piroplasmosis for nearly 30 years. Florida's Department of Agriculture and Consumer Services in February wrapped up on investigation into equine piroplasmosis in that state. During the investigation, officials quarantined 25 premises and tested more than 200 horses for the disease. In all, 20 horses on seven premises were euthanized after they were found to be infected with the organism that causes equine piroplasmosis.

Read more on the Missouri investigation.

About the Author

Erin Ryder

Erin Ryder is a former news editor of The Horse: Your Guide To Equine Health Care.

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