Management of an Equine Herpesvirus-1 Outbreak During a Multi-Week Equestrian Event

The present study reports on the management of an EHV-1 outbreak at a large, multi-week equestrian event with ongoing showing. Within a 48 h period, 8 horses out of a cohort of 38 horses from the same trainer displayed elevated rectal temperatures ranging from 38.4 to 39.0 °C. Initial testing using...

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Main Authors: Nicola Pusterla, Kaila Lawton, Samantha Barnum, Katie Flynn, Steve Hankin, David Runk, Eric Mendonsa, Tara Doherty
Format: Article
Language:English
Published: MDPI AG 2025-04-01
Series:Viruses
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Online Access:https://www.mdpi.com/1999-4915/17/5/608
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author Nicola Pusterla
Kaila Lawton
Samantha Barnum
Katie Flynn
Steve Hankin
David Runk
Eric Mendonsa
Tara Doherty
author_facet Nicola Pusterla
Kaila Lawton
Samantha Barnum
Katie Flynn
Steve Hankin
David Runk
Eric Mendonsa
Tara Doherty
author_sort Nicola Pusterla
collection DOAJ
description The present study reports on the management of an EHV-1 outbreak at a large, multi-week equestrian event with ongoing showing. Within a 48 h period, 8 horses out of a cohort of 38 horses from the same trainer displayed elevated rectal temperatures ranging from 38.4 to 39.0 °C. Initial testing using a point-of-care PCR assay detected EHV-1 in 2/8 horses, with the results being confirmed at a later time by qPCR. As a precautionary measure and because of the inability to isolate the entire at-risk population, the 38 horses were relocated to an equine facility outside the equestrian event for daily monitoring and weekly EHV-1 qPCR testing of nasal secretions. Overall, 22/38 (58%) horses tested EHV-1 qPCR-positive in nasal secretions over the monitoring period of 28 days, with only one additional horse developing fever. Once all 38 horses tested EHV-1 qPCR-negative twice, 7 days apart, 17 horses returned to the equestrian event to compete for the remaining 2 weeks of the circuit. The present study highlights the importance of isolating and testing horses with fever but also subfebrile horses, as EHV-1 can cause silent infection. The relocation of the exposed horses to an outside facility allowed close monitoring of these horses while reducing the risk of direct and indirect exposure to other show horses. The regular testing for EHV-1 through nasal secretions during the outbreak, coupled with proper biosecurity protocols, allowed the safe return of the show horses to the event. The key elements in reducing the spread of EHV-1 were the routine assessment of rectal temperature, early isolation of horses with elevated rectal temperature and on-site EHV-1 PCR testing.
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spelling doaj-art-c398b712ceae428aba1ea231ec9bbb232025-08-20T01:56:42ZengMDPI AGViruses1999-49152025-04-0117560810.3390/v17050608Management of an Equine Herpesvirus-1 Outbreak During a Multi-Week Equestrian EventNicola Pusterla0Kaila Lawton1Samantha Barnum2Katie Flynn3Steve Hankin4David Runk5Eric Mendonsa6Tara Doherty7Department of Medicine and Epidemiology, School of Veterinary Medicine, University of California, Davis, CA 95616, USADepartment of Medicine and Epidemiology, School of Veterinary Medicine, University of California, Davis, CA 95616, USADepartment of Medicine and Epidemiology, School of Veterinary Medicine, University of California, Davis, CA 95616, USAUS Equestrian Federation, Lexington, KY 40511, USADesert International Horse Park, Thermal, CA 92274, USADesert International Horse Park, Thermal, CA 92274, USAFluxergy, Irvine, CA 92618, USAWest Coast Equine Medicine, Temecula, CA 92590, USAThe present study reports on the management of an EHV-1 outbreak at a large, multi-week equestrian event with ongoing showing. Within a 48 h period, 8 horses out of a cohort of 38 horses from the same trainer displayed elevated rectal temperatures ranging from 38.4 to 39.0 °C. Initial testing using a point-of-care PCR assay detected EHV-1 in 2/8 horses, with the results being confirmed at a later time by qPCR. As a precautionary measure and because of the inability to isolate the entire at-risk population, the 38 horses were relocated to an equine facility outside the equestrian event for daily monitoring and weekly EHV-1 qPCR testing of nasal secretions. Overall, 22/38 (58%) horses tested EHV-1 qPCR-positive in nasal secretions over the monitoring period of 28 days, with only one additional horse developing fever. Once all 38 horses tested EHV-1 qPCR-negative twice, 7 days apart, 17 horses returned to the equestrian event to compete for the remaining 2 weeks of the circuit. The present study highlights the importance of isolating and testing horses with fever but also subfebrile horses, as EHV-1 can cause silent infection. The relocation of the exposed horses to an outside facility allowed close monitoring of these horses while reducing the risk of direct and indirect exposure to other show horses. The regular testing for EHV-1 through nasal secretions during the outbreak, coupled with proper biosecurity protocols, allowed the safe return of the show horses to the event. The key elements in reducing the spread of EHV-1 were the routine assessment of rectal temperature, early isolation of horses with elevated rectal temperature and on-site EHV-1 PCR testing.https://www.mdpi.com/1999-4915/17/5/608equine herpesvirus-1outbreakshow horsesmonitoringqPCR testingreturn to competition
spellingShingle Nicola Pusterla
Kaila Lawton
Samantha Barnum
Katie Flynn
Steve Hankin
David Runk
Eric Mendonsa
Tara Doherty
Management of an Equine Herpesvirus-1 Outbreak During a Multi-Week Equestrian Event
Viruses
equine herpesvirus-1
outbreak
show horses
monitoring
qPCR testing
return to competition
title Management of an Equine Herpesvirus-1 Outbreak During a Multi-Week Equestrian Event
title_full Management of an Equine Herpesvirus-1 Outbreak During a Multi-Week Equestrian Event
title_fullStr Management of an Equine Herpesvirus-1 Outbreak During a Multi-Week Equestrian Event
title_full_unstemmed Management of an Equine Herpesvirus-1 Outbreak During a Multi-Week Equestrian Event
title_short Management of an Equine Herpesvirus-1 Outbreak During a Multi-Week Equestrian Event
title_sort management of an equine herpesvirus 1 outbreak during a multi week equestrian event
topic equine herpesvirus-1
outbreak
show horses
monitoring
qPCR testing
return to competition
url https://www.mdpi.com/1999-4915/17/5/608
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