URT endoscopy | EQUINE
(Microsoft Excel 2007, Microsoft Corp, Redmond, WA,
USA). Results were expressed as a prevalence for each
grade. For analysis of the effects for gender on RLN
grading, horses with grades 1 and 2 were considered
“normal” and horses with grades 3 and 4 “abnormal”.
A Fisher’s exact test (Fisher 1922:87-94) was used to
determine if there was a relationship between gender
and grade, due to one or more instances of the expected
value being less than 5. For comparison of the effects of
age on grade, and sales year on grade, a Kruskal-Wallis
test was performed (Gibbons 1976). For all comparisons,
a value of P < 0.05 was considered significant. Statistical
Analysis was performed by SMM using SPSS (IBM Corp.
Released 2017. IBM SPSS Statistics for Windows, Version
25.0. Armonk, NY: IBM Corp.).
Results
858 horses out of a total of 4149 offered for sale over the
seven-year period (20.68 %) were examined. The horses
endoscopically examined per sale ranged between
13.71 – 26.85 %. There were 494 colts (57.58%) and
364 fillies (42.42%) examined, with a mean age at time
of examination of 18.1 months (range 13-26 months)
from 2013 to 2019. The mean percentage ± standard
deviation for grade 1 was: 84.04% ± 9.98, grade 2:
14.49% ± 10.69, grade 3: 0.71% ± 0.57 and grade 4 was:
0.76% ± 0.94% (Table 3).
Analysis of the effects for gender on RLN grading
showed no significant difference between colts and
fillies with grades 1 and 2 or with grades 3 and 4 RLN
(Table 3). There was also no significant effect of age on
grade. There was no significant difference in grades
compared by sales year.
Discussion
Table 4. Gender versus RLN grade in the present
study
Gender Grade 1 Grade 2 Grade 3 Grade 4
Colts 407 80 3 4
Fillies 305 56 2 1
Total 712 136 5 5
Table 3: Endoscopic examination grading of recurrent laryngeal neuropathy of yearlings at South African sales
from 2013 to 2019
Grade 2013 2014 2015 2016 2017 2018 2019 % Mean ±
STD
n % n % n % n % n % n % n %
Grade 1 65 95.96 81 78.64 67 83.75 119 85.61 133 92.36 142 87.12 105 65.22 84.04 ± 9.98
Grade 2 1 1.47 21 20.39 10 12.5 19 13.67 10 6.94 19 11.66 56 34.78 14.49 ±
10.69
Grade 3 1 1.47 1 0.9 1 1.25 0 0 1 0.69 1 0.61 0 0 0.71 ± 0.57
Grade 4 1 1.47 0 0 2 2.5 1 0.72 0 0 1 0.61 0 0 0.76 ± 0.94
Total
horses
68 103 80 139 144 163 161
n: Number of individuals, %: percentage, STD: Standard deviation
• Volume 22 Issue 02 | June 2020 •
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