UPDATE ON ‘POST-RACE DISTRESS SYNDROME’
IN THOROUGHBRED RACING IN SOUTH AFRICA
D.P. Wheeler, S.J. Coetzee, C. de Bruin and G.P. Andrews
National Horseracing Authority of Southern Africa, PO Box 74439, Turffontein, 2140, South Africa
ABSTRACT
Post-race Distress Syndrome (PRDS), as recognised in South Africa and reported
worldwide under a variety of names such as “Heat Stress”, is investigated by a
retrospective analysis of data maintained over a period of 26 years by the National
Horseracing Authority of Southern Africa (NHA).
Post-race distress as a syndrome is characterised by pathognomonic symptoms that
appear in the immediate post-race period and vary from mild distress to total
collapse. The syndrome is not reproducible on the treadmill or during racing gallops,
so it would appear that the added stress of racing plays a significant role.
The definition of PRDS as reported in the paper ‘Post Race Distress Syndrome’ in
Thoroughbred Racing in South Africa by Macdonald et al. (2008), has been
expanded to include horses showing dynamic obstruction of the upper respiratory
tract (stridor) and acute hind limb discomfort. This, together with an additional five
years of data, has provided a much larger case population thereby increasing the
significance of the findings.
The risk factors that are updated include season of the year, racing surface, age,
gender, headgear and distance. The additional aspects of going, transport and
hereditary factors that were not previously addressed are considered. Proposals for
further investigation are discussed.
INTRODUCTION
The syndrome as first described by Macdonald et al. (2008), is seen throughout the
world by racing jurisdictions and is reported under a variety of names including heat
stress, heat exhaustion, post-race collapse and post-exertional distress. The
incidence of PRDS has been increasing steadily every year (Fig 1). The definition as
given previously specifically excluded horses showing distress as a result of dynamic
obstruction of the upper respiratory tract. In the years following the publication of the
first paper, it has been observed that the symptoms exhibited by horses showing
“respiratory distress” are exactly the same as those for PRDS, albeit with the addition
of respiratory stridor. It was therefore decided to include these horses as part of the
syndrome.
Horses showing acute discomfort in the hind limbs, usually indicated by the horse
continuously kicking and/or bucking post-race, have also been included. The reason
for this is that these horses have often shown PRDS on different occasions and we
postulate that this is just another symptom of PRDS. The aim of this paper is to
update the previous paper and to offer insight in to other possible risk factors.
MATERIALS AND METHODS
This study was carried out over a period of 26 years from 1st August 1987 to 31st
July 2013 and includes all runners in flat races on 6 racecourses consisting of 6 turf
tracks and 2 sand tracks. These tracks all fall under the control of the Central
Proceedings
of
the
South
African
Equine
Veterinary
Association
Congress
2016
26