Investigation of the Use of Non-Invasive Samples for the Molecular Detection of EHV-1 in Horses with and without Clinical Infection

Abstract

The purpose of this study was to explore sampling options for a reliable and logistically more feasible protocol during a large EHV-1 outbreak. Seventeen horses with clinical infection as well as nineteen healthy herdmates, all part of an EHM outbreak, were enrolled in the study. Each horse was sampled two–four times at intervals of 2–6 days during the outbreak. All samples were collected using 6′′ rayon-tipped swabs. Nasal secretions were used as the diagnostic sample of choice. Additional samples, including swabs from the muzzle/nares, swabs from the front limbs, rectal swabs, swabs of the feed bin, and swabs of the water troughs were collected as well. All swabs were tested for the presence of EHV-1 by qPCR. With the exception of two EHV-1 qPCR-positive swabs from two different horses, all remaining swabs collected from healthy herdmates tested qPCR-negative for EHV-1. For horses with clinical infection, EHV-1 was detected in 31 nasal swabs, 30 muzzle/nares swabs, 7 front limb swabs, 7 feeders, 6 water troughs and 6 rectal swabs. Not all positive muzzle/nares swabs correlated with a positive nasal swab from the same set, however, and all other positive swabs did correlate with a positive nasal swab in their respective set. The agreement between nasal swabs and muzzle/nares swabs was 74%. The sampling of non-invasive swabs from the muzzle/nares should facilitate the identification of EHV-1 shedders during an outbreak, allowing for prompt isolation and implementation of biosecurity measures.

Detection of equine herpesvirus‐1 (EHV‐1) in urine samples during outbreaks of equine herpesvirus myeloencephalopathy

“…3 The identification of EHV-1 DNA in faecal swabs and semen in wild and domestic horses has also been reported 16,18,19,25 and there is a study reporting the presence of EHV-1 DNA in the muzzle/nares area of horses. 25 Free-catch urine can be regarded as a non-invasive specimen, and its collection is less traumatic than blood drawing, especially in horses suffering from vasculitis as occurs in EHV-1 infected horses. 3 In both 2021 and 2023 outbreaks in Spain the EHV-1 strain causing the outbreak was reported as genotype N752 (A2254), 26 unpublished data from the National Reference Laboratory (Algete, Spain).…”

“…The gold standard for EHV‐1 diagnosis is viral detection from nasopharyngeal swabs or blood 3 . The identification of EHV‐1 DNA in faecal swabs and semen in wild and domestic horses has also been reported 16,18,19,25 and there is a study reporting the presence of EHV‐1 DNA in the muzzle/nares area of horses 25 . Free‐catch urine can be regarded as a non‐invasive specimen, and its collection is less traumatic than blood drawing, especially in horses suffering from vasculitis as occurs in EHV‐1 infected horses 3 .…”

Cross-Sectional Survey of Horse Owners to Assess Their Knowledge and Use of Biosecurity Practices for Equine Infectious Diseases in the United States

“…Recent epidemiologic studies detected respiratory viruses EHV-1, EHV-4 and influenza virus in the nasal passage and lymph nodes of horses as well as in the facility environment confirming the potential risk of infection during a horse show and in recently imported horses [9][10][11]. EHV-1 and EHV-4 were also detected from feed bins and water troughs in addition to affected horses, confirming the risk of transmission during an outbreak [12]. Although EHV-4 usually causes mild clinical signs, a 17-week outbreak in Switzerland resulted in disease spread on a breeding farm, predominantly affecting foals.…”