46TH
ANNUAL
CONGRESS
OF
THE
SAEVA
SKUKUZA
16-‐20
FEBRUARY
2014
125
antibody concentrations due to vaccination or previous exposure was strongly
protective and a higher qPCR detection rate for EHV-1 and -4 was reported during
winter months. These have been postulated to be associated with management
practices e.g. a higher density of young animals kept indoors for training and sales
purposes. Arguably, one of the most important risk factors associated with
respiratory infections, is physiological stress. Stress has been associated with
recrudescence and shedding of latent EHV-1 and -4 infections and additionally the
immunosuppressive influence of stress on the body increases the susceptibility of
naive animals to new respiratory infections. Transport, confinement, handling and
management at a sales complex may contribute greatly to the physiological stress
experienced by young animals.
Information about the prevalence of important equine respiratory pathogens and
nasal shedding and any association with health, vaccination status or management
factors, will increase understanding of the risks to horses attending sales events in
South Africa and enhance the ability to design risk mitigation and management
strategies.
Prospective cohort studies in Thoroughbred horses < 2 years-old consigned to
bloodstock sale aimed to determine:
• Prevalence of EHV-1 and -4 shedding by serial nasal swab collection for qPCR
testing in suspect cases of infection; and
• Facility of early detection of possible respiratory infections by monitoring horses
for elevated rectal temperature and nasal discharge;
Materials and methods
Data was collected at two separate Thoroughbred Breeders Association (TBA)
National Two Year-Old Sales during August of 2011 and 2013 at the Gosforth Park
Sales Complex in Germiston, Gauteng Province. The horses’ stay following arrival at
the Complex consisted of an approximately weeklong pre-sales preparation followed
by the actual sales occurring over the final 2 days before departure.
The study populations’ were colts and fillies selected from the TBA’s Sales Catalogue
and based on stud farm owners’ willingness to participate in the study and previous
experience regarding the availability of accurate records from these farms. In 2011,
preliminary data was obtained from 35 animals originating from one farm in the
Eastern Cape (n=19 horses) and one in KwaZulu-Natal (n=16 horses) Provinces,
respectively. In 2013, a more extensive study observed 93 animals from 8 farms
situated in the Western Cape (n=3 farms; 31 horses), Eastern Cape (n=2 farms; 18
horses) and KwaZulu-Natal (n=3 farms; 44 horses) Provinces, respectively.
Upon arrival at the sales complex, nasal swabs for molecular detection of viral
nucleic acid using a duplex quantitative-polymerase chain reaction (qPCR) for EHV-1
and EHV-4 were collected. Duplicate 15 cm metal shaft rayon-tipped swabs were
advanced simultaneously into the ventral meatus of either the horse’s left or the
right nostril and gently rotated against the mucous membranes. Following this, each
swab was placed in a sterile, dry, 15 ml conical tube, refrigerated at 4–6 °C and
transported on ice to Faculty of Veterinary Science, University of Pretoria and a
qPCR analysis was performed according to the method of Diallo et al, (2007).
Thereafter, twice-daily monitoring for clinical evidence of pyrexia and nasal discharge
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