Testing Confirms Potomac Horse Fever in a Maryland Pony

A pony from Frederick County, Maryland, died July 30 after contracting Potomac horse fever.

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Potomac horse fever in a Maryland pony
Horses are exposed by inadvertently ingesting aquatic insects infected with flukes carrying the causative bacteria or by drinking flukes directly from rivers or streams. | Photo: iStock

The Maryland Department of Agriculture (MDA) reported that test results confirmed a case of Potomac horse fever in a Maryland pony.

The MDA said samples sent to the University of Kentucky’s Equine Diagnostic Laboratory on Aug. 2 returned positive for Potomac horse fever (PHF). The pony from Frederick County fell ill on July 26 and did not respond to treatment. The gelding died on July 30, and staff at the Frederick Animal Health Laboratory performed a necropsy on July 31.

Neorickettsia risticii, an organism found in some wormlike parasites that infect aquatic snails and insects (such as caddisflies and mayflies) causes PHF

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Written by:

Erica Larson, former news editor for The Horse, holds a degree in journalism with an external specialty in equine science from Michigan State University in East Lansing. A Massachusetts native, she grew up in the saddle and has dabbled in a variety of disciplines including foxhunting, saddle seat, and mounted games. Currently, Erica competes in eventing with her OTTB, Dorado.

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