Discussion

Thomas, A.D., Green, M.J., Morris, T., Bowen, N. and Hallowell, G.D.
School of Veterinary Medicine and Science, University of
Nottingham, Sutton Bonington, UK; and British Horseracing
Authority, London, UK. Email: svydat@nottingham.ac.uk
Aims: To report prevalence, incidence and recurrence of epistaxis,
identify risk factors and report effects of epistaxis upon
performance. Methods: Cases of epistaxis were identified from
all UK race starts (914,849) from 2001 to 2010 using veterinary
surveillance. Multivariable mixed effect step-wise logistic
regression models were used to identify risk factors. Results: A
total of 2076 cases of epistaxis in 1776 horses were identified.
The overall prevalence of epistaxis was 0.23%. Prevalence was
0.13% in flat racehorses, 0.34% in hurdlers and 0.54% in
steeplechasers. Incidence was 10.6 cases per 1000 horses per year
with 2.3% of the racing population affected by epistaxis.
Prevalence and incidence increased over the decade studied.
Horses that raced over fences (P<0.001), competed over shorter
distances (within race types; P<0.001) and on firmer going
(P<0.001) showed increased epistaxis prevalence. Age only
increased epistaxis risk in flat horses (P = 0.004). Horses with
epistaxis were likely to have raced over more seasons (P<0.008),
but had a lower number of starts per season (P = 0.03) and a
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longer period between races (P<0.0001). The number of days
since the last race was higher for epistaxis performances (67 days;
P<0.003) when compared with controls (58 days). Horses with
epistaxis demonstrating recurrence was 13.5% (15.9%,10.1%
and 17.7% for flat racehorses, hurdlers and steeplechasers,
respectively). Recurrence within a year was lower in steeplechase
(63.7%) races when compared to flat (75.6%) and hurdle races
(76.2%; P<0.001). Twenty-eight day race bans would only
prevent recurrence in <10% of cases. All performance indicators
demonstrated inferior race performance in horses with epistaxis.
A high percentage of horses with epistaxis did not finish (~10%
flat to ~60% over jumps). Conclusion: It is the intensity of racing
that affects the prevalence of epistaxis. Practical significance:
Epistaxis is associated with inferior race performance and
noncompletion. Race bans will have limited effect in preventing
recurrence and trainers already delay racing post epistaxis.