Frequency of shedding of respiratory pathogens in horses recently imported to the United States.
Abstract: Imported horses that have undergone recent long distance transport might represent a serious risk for spreading infectious respiratory pathogens into populations of horses. Objective: To investigate the frequency of shedding of respiratory pathogens in recently imported horses. Methods: All imported horses with signed owner consent (n = 167) entering a USDA quarantine for contagious equine metritis from October 2014 to June 2016 were enrolled in the study. Methods: Prospective observational study. Enrolled horses had a physical examination performed and nasal secretions collected at the time of entry and subsequently if any horse developed signs of respiratory disease during quarantine. Samples were assayed for equine influenza virus (EIV), equine herpesvirus type-1, -2, -4, and -5 (EHV-1, -2, -4, -5), equine rhinitis virus A (ERAV), and B (ERBV) and Streptococcus equi subspecies equi (S. equi) using quantitative PCR (qPCR). Results: Equine herpesviruses were detected by qPCR in 52% of the study horses including EHV-2 (28.7%), EHV-5 (40.7%), EHV-1 (1.2%), and EHV-4 (3.0%). Clinical signs were not correlated with being qPCR-positive for EHV-4, EHV-2, or EHV-5. None of the samples were qPCR-positive for EIV, ERAV, ERBV, and S. equi. The qPCR assay failed quality control for RNA viruses in 25% (46/167) of samples. Conclusions: Clinical signs of respiratory disease were poorly correlated with qPCR positive status for EHV-2, -4, and -5. The importance of γ-herpesviruses (EHV-2 and 5) in respiratory disease is poorly understood. Equine herpesvirus type-1 or 4 (EHV-1 or EHV-4) were detected in 4.2% of horses, which could have serious consequences if shedding animals entered a population of susceptible horses. Biosecurity measures are important when introducing recently imported horses into resident US populations of horses.
Copyright © 2018 The Authors. Journal of Veterinary Internal Medicine published by Wiley Periodicals, Inc. on behalf of the American College of Veterinary Internal Medicine.
Publication Date: 2018-05-15 PubMed ID: 29761571PubMed Central: PMC6060314DOI: 10.1111/jvim.15145Google Scholar: Lookup
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- Journal Article
- Observational Study
- Biosecurity
- Clinical Signs
- Contagious Equine Metritis
- Diagnosis
- Disease Diagnosis
- Disease Transmission
- Epidemiology
- Equine Health
- Equine Herpesvirus
- Equine Rhinitis Virus
- Horse Transport
- Horses
- Importation
- Infectious Disease
- Influenza
- Observational Study
- Polymerase Chain Reaction
- Public Health
- Respiratory Disease
- Streptococcus
- Veterinary Medicine
Summary
This research summary has been generated with artificial intelligence and may contain errors and omissions. Refer to the original study to confirm details provided. Submit correction.
This research aimed to investigate how often recently imported horses in the United States shed respiratory pathogens, given that these animals, having undergone recent long-distance transport, could pose significant risks for spreading infectious diseases. The analysis revealed that over half of the study subjects were shedding equine herpesviruses, but it also showed a poor correlation between clinical signs of respiratory disease and the positive presence of such viruses in horses. The study calls for robust biosecurity measures when incorporating newly imported equines into local U.S. horse populations.
Research Methodology
- The study involved imported horses that were granted owner consent to participate in the research.
- The timeline for this study was between October 2014 and June 2016.
- Upon entering a USDA quarantine for contagious equine metritis, all included horses underwent physical examination and nasal secretion collection.
- If any horse displayed symptoms of respiratory disease during quarantine, additional nasal secretions were collected from them.
- Collected samples were tested for various pathogens: equine influenza virus (EIV), equine herpesvirus type-1, -2, -4, and -5 (EHV-1, -2, -4, -5), equine rhinitis virus A (ERAV), and B (ERBV), and Streptococcus equi subspecies equi (S. equi) through a quantitative PCR (qPCR) assay.
Research Findings
- Through qPCR, equine herpesviruses were detected in 52% of the horses involved in the study
- Among these, EHV-2 was present in 28.7% of horses, EHV-5 in 40.7%, EHV-1 in 1.2%, and EHV-4 in 3.0%.
- No correlation was found between clinical signs and horses being qPCR-positive for EHV-4, -2, or -5.
- None of the samples were qPCR-positive for EIV, ERAV, ERBV, and S. Equi.
- The qPCR assay failed quality control in 25% of the samples strictly related to RNA viruses.
Conclusion and Implications
- Findings showed poor correlations between clinical respiratory disease signs and being qPCR positive for EHV-2, -4, and -5.
- The function of γ-herpesviruses (EHV-2 and 5) in respiratory disease is not fully understood.
- The discovery of equine herpesvirus type-1 or 4 (EHV-1 or EHV-4) in 4.2% of the horses could pose severe implications if such horses entered a population of susceptible horses.
- The study emphasizes the need for strict biosecurity protocols when introducing recently imported horses into existing US populations of horses in order to prevent potential disease spread.
Cite This Article
APA
Smith FL, Watson JL, Spier SJ, Kilcoyne I, Mapes S, Sonder C, Pusterla N.
(2018).
Frequency of shedding of respiratory pathogens in horses recently imported to the United States.
J Vet Intern Med, 32(4), 1436-1441.
https://doi.org/10.1111/jvim.15145 Publication
Researcher Affiliations
- Willian R Pritchard Veterinary Medical Teaching Hospital, University of California Davis, Davis, California.
- Department of Medicine and Epidemiology, University of California Davis, Davis, California.
- Department of Medicine and Epidemiology, University of California Davis, Davis, California.
- Department of Surgical and Radiological Sciences, University of California Davis, Davis, California.
- Department of Medicine and Epidemiology, University of California Davis, Davis, California.
- Center for Equine Heath, School of Veterinary Medicine, University of California, Davis, Davis, California.
- Department of Medicine and Epidemiology, University of California Davis, Davis, California.
MeSH Terms
- Animals
- Female
- Herpesviridae Infections / veterinary
- Herpesviridae Infections / virology
- Herpesvirus 1, Equid
- Herpesvirus 4, Equid
- Horse Diseases / epidemiology
- Horse Diseases / microbiology
- Horse Diseases / transmission
- Horse Diseases / virology
- Horses / microbiology
- Horses / virology
- Male
- Prospective Studies
- Quarantine / veterinary
- Real-Time Polymerase Chain Reaction / veterinary
- Respiratory Tract Diseases / microbiology
- Respiratory Tract Diseases / veterinary
- Respiratory Tract Diseases / virology
- Rhadinovirus
- Streptococcal Infections / microbiology
- Streptococcal Infections / transmission
- Streptococcal Infections / veterinary
- Streptococcus equi
- United States / epidemiology
- Virus Shedding
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