Page 1032 - Adams and Stashak's Lameness in Horses, 7th Edition

998 Chapter 9

THE ENDURANCE HORSE

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THE SPORT FEI competition. FEI competitions are categorized by
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course difficulty: horses must be 6 years old to enter 1*
The sport of equine endurance has grown substan­ and 2* rides, 7 years old to enter 3* rides, and 8 years
tially since the American Endurance Ride Conference old to enter 4* rides. 6
(AERC) was established as the national governing body Although most competitive horses in the sport are of
for long‐distance riding in 1972. Under current rules, Arabian influence, their individual conformation can
the AERC recognizes endurance competitions that cover vary widely. Those with a long competitive career usu­
distances of at least 50 miles/day up to a maximum dis­ ally have few striking conformational flaws; however
tance of 150 miles in 3 days. Pioneer rides may be up to many horses with less‐than‐perfect conformation (e.g.
5 days in duration; in that case, 1 day must be 55 miles, toed in or out, high/low heel, contracted heels, post‐
and the remaining are 50 miles. 8 legged, sickle hocked, etc.) can be competitive in the
The sport originated in the United States, where the sport. Coupled with the magnitude of distance covered,
Western States Trail Ride 100‐mile competition (also the environmental conditions in terms of both topo­
known as the Tevis Cup) has been held in the Sierra graphical terrain variation as well as heat and humidity
mountain range since 1955. Endurance events covering extremes create exercise conditions that are among the
distances of 80–160 km have been regulated by the most challenging of any equine sport. Lameness and
Federation Equestre Internationale (FEI) since 1982. metabolic disturbances are the two most common
The sport has subsequently undergone tremendous reasons for elimination during competitions.
growth internationally. In 2010, a new world record
was set in a 100‐mile (160‐km) endurance competition
in Dubai, United Arab Emirates. The winning time was
5 hours, 45 minutes, 44 seconds, at an average speed of
27.77 km/hour. The trend of faster speeds associated VETERINARY CONTROL
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with less technically demanding competitions in interna­ Endurance is one of the most stringently controlled
tional events in comparison to national events is well equine sports in terms of veterinary oversight during
recognized. competition. Horses are initially examined prior to the
Typically, AERC rides are composed of both limited ride to determine suitability to enter competition. The
distance competitions (25–35 miles) and AERC‐recog­ examination includes a basic physical and lameness
nized endurance competitions, ranging from 50 to 100 examination. At the pre‐ride inspection, joint or tendon
miles. Over the past 10 ride seasons (2007–2016) in the sheath effusion and abrasions or scars are entered on the
United States, the AERC recognized an average of 269 ride card horse diagram, similar to markings on a
yearly rides in which 19,575 horses competed each Coggin’s form (Figure 9.42). 8
year. While completion rates typically vary with ride The ride is divided into segments or phases. An
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conditions and level of competition, the average comple­ examination determines fitness to continue at the end
tion rate over the past 10 AERC seasons has been of each phase at a veterinary check point or “vet gate.”
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86.25%. Completion rates for international competi­ Short rides may only have one vet gate, whereas 160‐
tions are not typically this high. In a recent review of km competitions may have as many as 7. Physical
30,741 horse starts at 100–160 km FEI endurance examination parameters evaluated and recorded on
rides—in 47 countries between 2008 and 2011, comple­ the ride card at each vet gate include pulse and res­
tion rate was 50.7%. Furthermore, a notable inverse piratory rate (PR), mucous membrane character,
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relationship has been documented between mean com­ capillary refill time, jugular vein refill, skin turgor,
petition speeds and completion rate. In both national gastrointestinal sounds, back and withers sensitivity,
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and international venues, the primary reason for elimi­ rubs or sores from the bit or tack, muscle tone, anal
nation from endurance competition is lameness. tone, gait, impulsion, and overall impression. Criteria
are recorded on a ride card using a scale of A to D,
with A considered normal (Figure 9.42). Rectal tem­
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ATHLETES AND EXERCISE CONDITIONS perature is often only measured and recorded in horses
exhibiting signs of heat stress.
The suitability of pure Arabians and Arabian crosses Horses must meet a pulse criterion that is set prior to
is well recognized for long‐distance aerobic exercise. competition (usually 64 beats/minute within 30 minutes
However, most endurance rides are open to horses of of entering the vet gate). A cardiac recovery index is
other breeds, with the exception of breed‐sanctioned determined in conjunction with the lameness examina­
competitions (i.e. Arabian Horse Association). tion by assessing the heart rate before and 1 minute after
Frequently, suitable athletes compete from the age of initiating an 80‐m trot (40 m out and back). After the
eligibility for 8–12 years. It is not uncommon for some trot‐out, if the horse’s heart rate increases by four or
horses to compete well into their 20s. The current mini­ more beats, metabolic criteria coupled with other
mum age limit is 5 years for AERC and novice levels of physical exam findings are scrutinized in more depth to