title: Detection of equine herpesvirus-4 and physiological stress patterns in young Thoroughbreds consigned to a South African auction sale.
abstract: BACKGROUND
  The prevalence of equine herpesvirus types-1 and -4 (EHV-1 and -4) in South African Thoroughbreds at auction sales is currently undefined. Commingling of young Thoroughbreds from various populations together with physiological stress related to their transport and confinement at a sales complex, may be associated with shedding and transmission of EHV-1 and -4. This prospective cohort study sampled 90 young Thoroughbreds consigned from eight farms, originating from three provinces representative of the South African Thoroughbred breeding demographic to a sales complex. Nasal swabs for quantitative real-time polymerase chain reaction (qPCR) assay to detect EHV-1 and -4 nucleic acid and blood samples for enzyme-linked immunosorbent assay for EHV-1 and -4 antibodies were collected from all horses on arrival and departure. Additional nasal swabs for qPCR were obtained serially from those displaying pyrexia and, or nasal discharge. Daily faecal samples were used for determination of faecal glucocorticoid metabolite (FGM) concentrations as a measurement of physiological stress and these values were modelled to determine the factors best explaining FGM variability.
  
  
  RESULTS
  EHV-4 nucleic acid was detected in 14.4 % and EHV-1 from none of the animals in the study population. Most (93.3 %) and very few (1.1 %) of this population showed antibodies indicating prior exposure to EHV-4 and EHV-1 respectively. Pyrexia and nasal discharge were poor predictors for detecting EHV-4 nucleic acid. The horses' FGM concentrations increased following arrival before decreasing for most of the remaining study period including the auction process. Model averaging showed that variation in FGM concentrations was best explained by days post-arrival and transport duration.
  
  
  CONCLUSIONS
  In this study population, sales consignment was associated with limited detection of EHV-4 nucleic acid in nasal secretions, with most showing prior exposure to EHV-4 and very few to EHV-1. The physiological stress response shown by most reflected the combination of stressors associated with transport and arrival and these are key areas for future investigation into management practices to enhance health and welfare of young Thoroughbreds during sales consignment.
authors.affiliation: Department of Companion Animal Clinical Studies, Faculty of Veterinary Science, University of Pretoria, Private Bag XO4, Onderstepoort, 0110, South Africa. marcha.badenhorst@up.ac.za.
authors.forename: Marcha
authors.initials: M
authors.lastname: Badenhorst
authors.affiliation: Department of Companion Animal Clinical Studies, Faculty of Veterinary Science, University of Pretoria, Private Bag XO4, Onderstepoort, 0110, South Africa. patrick.page@up.ac.za.
authors.forename: Patrick
authors.initials: P
authors.lastname: Page
authors.affiliation: Department of Anatomy and Physiology, Faculty of Veterinary Science, University of Pretoria, Private Bag XO4, Onderstepoort, 0110, South Africa. aganswindt@zoology.up.ac.za.
authors.forename: Andre
authors.initials: A
authors.lastname: Ganswindt
authors.affiliation: Department of Anatomy and Physiology, Faculty of Veterinary Science, University of Pretoria, Private Bag XO4, Onderstepoort, 0110, South Africa. pnlaver@gmail.com.
authors.forename: Peter
authors.initials: P
authors.lastname: Laver
authors.affiliation: Equine Research Centre, Faculty of Veterinary Science, University of Pretoria, Private Bag XO4, Onderstepoort, 0110, South Africa. alan.guthrie@up.ac.za.
authors.forename: Alan
authors.initials: A
authors.lastname: Guthrie
authors.affiliation: Section of Reproduction, Department of Production Animal Clinical Studies, Faculty of Veterinary Science, University of Pretoria, Private Bag XO4, Onderstepoort, 0110, South Africa. martin.schulman@up.ac.za.
authors.forename: Martin
authors.initials: M
authors.lastname: Schulman
mesh_terms: D000818:Animals; D000914:Antibodies, Viral / Q000097:blood; D015331:Cohort Studies; D003132:Commerce; D004279:DNA, Viral / Q000097:blood / Q000302:isolation & purification; D005243:Feces / Q000737:chemistry; D006566:Herpesviridae Infections / Q000453:epidemiology / Q000662:veterinary* / Q000821:virology; D023141:Herpesvirus 4, Equid / Q000302:isolation & purification*; D006728:Hormones / Q000737:chemistry; D006734:Horse Diseases / Q000821:virology*; D006736:Horses; D013019:South Africa / Q000453:epidemiology; D013312:Stress, Physiological
chemical_list: D000914:Antibodies, Viral; D004279:DNA, Viral; D006728:Hormones