POTOMAC HORSE FEVER – Everything you need to know

Potomac horse fever:

What is it?

• A bacterial infection caused by Neorickettsia risticii carried by flat worms (Flukes)

• Symptoms seen in your horse:

  • fever

  • laminitis/founder

  • Dehydration/ pipe-stream diarrhea

  • Mild-severe colic

  • Abortion in pregnant mares

  • Toxemia

How does my horse get it?

1. Flat worms typically found in snails which are then released into water source

2. Water insects pick up infected immature flat worm and transmit it to the horse via ingestion of insect (e.g. grazing/ drinking)

What time of year do I need to be aware of this disease?

• During warmer months ( late spring, summer, early fall)

  • Atypical weather such as flooding and high humidity can heighten likeliness of exposure

Where is it commonly found?

• Freshwater creeks

• Rivers

• Irrigated pastures

• Standing water

• Swamps

• Wetlands

How do I protect my horse?

• Your horses don’t necessarily have to reside in an area where natural waterbodies are found

  • Dead or live insects that carry the bacterium may be found in water buckets, hay or pasture

• At ECO we recommend you vaccinate your horse at the beginning of the warmer months and repeat boosters every 3 months after due to unknown protection levels and efficacy levels)

• Restrict grazing time near bodies of water

• Use preventive measuresPreventative Medicine to decrease fly and insect population

• Cover horse feed

• Clean and refill water buckets daily

• Turn light off at night to reduce insect attraction

Sources: AAEP article By Eleanor Lenher, DVM “Potomac Horse Fever (PHF)” 2016

Text–Large animal Clinical procedures 2nd ed by Kristin Holtgrew-Bohling, LVT 2012