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.