Equine gastric ulcer syndrome in New Zealand racehorses
Master of Veterinary Science
2006
Robin Joseph Wallace Bell
Aims
To establish the prevalence of gastric ulcers in New Zealand racehorses, and to validate a
scoring system for the endoscopic grading of gastric ulcers in horses.
Methods
A prevalence study was conducted during 2003 and 2004 in New Zealand. One hundred
and seventy one horses from 24 trainers across New Zealand were examined with
gastroscopy as part of the study. Images of the examination were recorded and reviewed.
The stomachs were assigned an ordinal score based on the severity of the gastric
ulceration present. Digitised recordings of 22 horses that were part of the prevalence
study into gastric ulceration in New Zealand racehorses were reviewed independently by
3 examiners. All 22 of these stomachs were graded using two different systems, the
Equine Gastric Ulcer Council (EGUC) system and the Number Severity (N/S) system
Results
There were 171 horses in the study: 133 Thoroughbreds and 38 Standardbreds. One
hundred and fifty one (88.3%) of these had evidence of EGUS. There was no significant
difference in the prevalence of ulceration between the two breeds (p=0.51) or between
horses of differing ages (p=0.56). There were 141 horses kept at pasture for at least four
hours per day, of these 125 (89%) had EGUS. Thirteen horses were kept at pasture full
time and all of these had EGUS. Seventeen horses were stabled full time and 16 (94.1%)
of these had EGUS. There was no significant difference between the different housing
groups and the prevalence or severity of EGUS (p=0.33 and 0.13 respectively), and there
was no significant difference in the severity of gastric ulceration (p=0.12) between the
horses grazed on different pasture qualities. There was no significant difference in the
prevalence (p=0.26) or severity (p=0.49) of gastric ulceration based on the duration of
training. All examiners commented that the EGUC system was the quickest and easiest to
use. There was no significant difference between examiners using the EGUC system
(p=0.31) and the agreement between observers was high, with Kappa values of 0.851vs2,
0.881vs3 and 0.802vs3. There was a significant difference between grades assigned by
examiners with the severity component of the N/S system (pseverity=0.005).
Conclusions
The prevalence of EGUS in New Zealand racehorses is similar to that reported elsewhere
for horses in active race training. The type of turnout that these horses receive does not
appear to be protective for EGUS. The EGUC system has better repeatability between
examiners and is faster and easier to use than the N/S system
Clinical relevance
Pasture turnout alone may not be protective against EGUS in racehorses that are in active
training. Gastric ulceration is a common problem in New Zealand racehorses and may be
a cause of decreased performance in these animals. The EGUC system is suitable as a
standard scoring system due to its ease of use, and the repeatability and correlation of
grades assigned between independent examiners. Use of a standard scoring system will
more easily allow comparisons to be made between different research groups and
clinicians.