A 4-year-old Quarter Horse gelding in Rocky View County, Alberta, tested positive for Potomac horse fever (PHF) on Oct. 7. The horse showed clinical signs on Sept. 30, such as inappetence, dullness, and diarrhea, but is currently recovering.
EDCC Health Watch is an Equine Network marketing program that utilizes information from the Equine Disease Communication Center (EDCC) to create and disseminate verified equine disease reports. The EDCC is an independent nonprofit organization that is supported by industry donations in order to provide open access to infectious disease information.
About Potomac Horse Fever
Potomac horse fever is caused by Neorickettsia risticii, an organism found in parasites, called flukes (flatworms), that infect aquatic snails and insects. Horses can become infected by consuming insects carrying Potomac horse fever or by drinking water containing N. risticii. Additionally, horses can contract Potomac horse fever by inadvertently ingesting infected insects or parasites in feed, water, or on pasture.
The incubation period for Potomac horse fever is between one and three weeks, with a mortality rate of up to 30%. Although vaccines against Potomac horse fever are not 100% effective, vaccinated horses typically exhibit fewer and less severe clinical signs.
Most cases of Potomac horse fever are reported from July to September, with outbreaks being seasonal.
Horse owners and caretakers, particularly those with horses near creeks and rivers, should be vigilant for signs such as:
- Diarrhea
- Colic
- Loss of appetite
- Lethargy
- Toxic shock
- Dehydration
- Abortion in pregnant mares
- Laminitis
- Mild to severe fever.