URT endoscopy | EQUINE
Table 1. Comparison of previous similar studies performed.
Author Location Horses Grade (%)
1 2 3 4
Stick et al. 2001 US TB yearlings 35.0 40.0 22.0 3.0
Garrett et al. 2010 US yearlings at auction 19.0 79.0 2.0 0.0
Brown et al. 2005 Australia competing racehorses - 1.3 1.3 0.0
Anderson et al. 1997 NZ young racehorses 52.0 33.0 14.0 1.0
Pascoe et al. 1981,
Raphael 1982, Sweeny
et al. 1991
North
America
race horses - 3.8 3.8 1.3-3.3
two to nine years old (mean four years old), RLN was
found at a prevalence of grade 1 in 96%, grade 2 in 1.8%
and 3 in 0.4% and grade 4 in 0.6% of TB race horses
(Saulez & Gummow 2009:431-435). This study compares
favourably with the Australian report which used a
similar cross-sectional inclusion criteria and grading
scale for RLN and also evaluated racehorses soon after
racing (Brown, et al. 2005:397-401).
During South African yearling sales, the horses are
endoscopically examined post-sale before release from
the sales grounds, by a veterinarian appointed by the
buyer. Any horse having been found to have a number
of URT abnormalities is liable to ‘fail’ the URT endoscopic
examination and the sale is cancelled. This differs from
a number of international sales where endoscopic
examination is requested by the sales company such
as New Zealand Bloodstock (Kelly 2016). A decision
regarding the grading is made by an expert panel
where video endoscopic examination is performed
and independent assessments are made, followed by a
consensus decision. In other countries, such as the UK
and Ireland, horses are lunged by the sales company and
only horses making an abnormal respiratory noise are
endoscopically examined (Kelly 2016).
The aim of this descriptive study is to determine the
prevalence of RLN grades at South African premier
TB yearling sales. To the author’s knowledge, RLN in
South African TB premier yearling sales has not been
investigated or previously reported.
Study Design and Case Selection
This study was designed as a retrospective analysis of
URT endoscopic examinations to determine RLN grade,
performed at two premier Thoroughbred yearling
sales (2013-2019) held in South Africa annually. Results
of endoscopic examinations performed on behalf of
buyers for one particular equine veterinary practice for
sales from 2013 to 2019 for the first premier sale and
from 2016 to 2019 for the second premier sale were
included in the study. A total of 858 horse out of 4149
(20.68 %) offered for sale where examined.
Cases included were all Thoroughbred yearlings offered
at public auction that were requested for examination
by the purchaser. Records of the results of these
• Volume 22 Issue 02 | June 2020 •
25