Throw together 10 veterinary clinicians and scientists as task-force members, mix in seven AERC directors, and sprinkle in two Vet Committee members. Trap in a single conference room and mix vigorously for for 25 hours, broken only by one night's sleep. What do you have? The AERC Research Summit held this August in Denver, just before the mid-year board meeting.

Chaired by Trisha Dowling (University of Saskatchewan) and Hal Schott (Michigan State University), the summit featured presentations of endurance horse sports medicine by David Marlin (Hartpury College, U.K.), Todd Holbrook (Oklahoma State University), Langdon Fielding, Olin Balch, Meg Sleeper (University of Pennsylvania), Pat Harris (Waltham Centre for Pet Nutrition, U.K.), and Drs. Dowling and Schott. Midge Leitch (University of Pennsylvania) attended and was sponsored by the American Association of Equine Practitioners as chair of their welfare committee.

In order to squeeze in as much productivity as possible, mealtimes included group discussions focused on problem identification, solutions and funding opportunities. Afterwards each group presented their findings to the entire Research Summit. Presentations and discussions were far-ranging and explored causes of endurance morbidity and mortality, suggested optimal research protocols, and concentrated on imaginative solutions for endurance horse disease. Future EN issues will feature highlights of some individual presentations.

AERC fatality summary

Discussions of equine welfare often begin with mortalities in that sport. The catastrophic breakdown of the filly Eight Belles in the 2008 Kentucky Derby riveted the public's attention on Thoroughbred racing. Within a month, an Associated Press report noted "more than three horse deaths a day last year [2007] and 5,000 since 2003, and the vast majority were put down after suffering devastating injuries on the track."

Fatalities do occur in endurance rides. Fortunately, these fatalities are extremely infrequent. AERC currently has seven complete years of mortality data. Essentially there were a handful of fatalities each year out of 21,000 to 23,000 horse starts annually. Laura Hayes, Welfare of the Horse Committee chair, reports annually on fatalities in the previous year. For any single year, the deaths are so infrequent that it is impossible to identify trends.

The summit featured an in-depth discussion of AERC's 2002 to 2008 fatality records. During that seven-year period, there were 57 fatalities for 154,151 starts. AERC has consistently thrown a very wide net to capture all fatality data, even remotely related to endurance rides. Consequently, AERC data include on-site horses only peripherally involved in the sport and, on at least two occasions, horses that were euthanized weeks or months later.

Almost one-third of these fatalities could be argued as non-endurance-specific. While very unfortunate, injuries associated with horses throwing riders and becoming lost in the woods, falling off trails, and escaping from corral fencing at 3:00 a.m. are a part of back-country horse camping and riding and not necessarily specific to endurance riding. While these types of fatalities are difficult subjects for systematic research, this is vital information for consideration if ride managers are to make ride camp and trails as safe as possible.

The other two-thirds of the fatalities do appear related to the specific challenges and stresses of endurance riding. The following are some common statistics for those 39 horses:

Acute abdomen or colic-like symptoms: 79%

Euthanized: 77%

Rode designated ride distance: 48%

Post mortem examinations: 47%

Received ride completions: 35%

Declined referral to advanced-care facilities or declined surgery when recommended: 25%

Gastric rupture confirmed (likely underestimated as necropsy is necessary for confirmation): 14%

Laminitis identified: 13%

Myositis identified: 10%

Renal disease identified: 5%

Additionally, horses with the least amount of endurance experience appear to be at greatest risk. Conversely, horses with the greatest amount of endurance experience appear to be at the least risk. Interestingly, extensive endurance-riding experience by the rider does not appear to be protective in preventing fatalities.

There may be significant regional differences in fatality occurrences. From 2002 to 2008, the Central Region had no fatalities, but the Mountain Region had eight, despite very similar numbers of starts (approximately 14,500).

Looking at the distance of rides, the frequency of LD fatalities is only slightly greater than the USDA-calculated expected death rate of horses in the general population aged 5 to 20 for any two-day period. If so, then LD rides as currently managed by the AERC are relatively safe equestrian activities.

On the other hand, 50 milers have fatalities that are three times more frequent than fatalities in LD rides; 100 milers have fatalities that are 10 times more frequent.

Are these differences statistically significant? With such small number of fatalities, some of above differences may be coincidental and not merit further study. The summit task force encourages the AERC to fund more rigorous statistical analysis of this already summarized and tabulated fatality data. This is necessary to ensure that only statistically valid differences are further investigated.

Concerns/solutions presented

The summit identified five major concerns and possible solutions, as well as evidence and explanations for changes, as noted below.

Concern #1: Excessive numbers of horses with eventual endurance-related fatalities are not identified earlier, if at all, during the actual competition.

Solution: Change the customary heart-rate (HR) recovery period at the end of the ride from the standard 60-minute period to a 30-minute period.

Evidence/explanation: Mortality data determined that more than one-third of eventual fatalities had actually met all veterinary requirements for completions (sound at movement, metabolically stable, and fit to continue). Simply put, there is inadequate identification of horses in dire trouble at the finish when using a 60-minute period for HR recovery. In the opinion of some of the task force, the use of a 60-minute recovery period for non-LD rides is such a lenient metabolic standard that it encourages some competitors to override their horses at the finish.

Interestingly, LDs have much stricter HR finish requirements and far fewer fatalities relative to the number of horses competing.

In her talk on heart rate recovery, Meg Sleeper, VMD (Diplomate ACVIM Cardiology), addressed the time period necessary for the HR to return to normal, post-exercise. The best science today confirms that "normal horses consistently recover to a heart rate of 64 bpm in less than 15 minutes post exercise," she said.

Almost all AERC Veterinary Committee members support a 30-minute HR recovery period at the finish. Currently, FEI specifies a maximum pulse at vet gates of 64 bpm within 20 minutes and a maximum pulse at the finish of 64 bpm within 30 minutes.

Concern #2: 79% of the endurance-related fatalities are associated with acute abdomens (colics) that are not identified early and successfully treated.

Solution: Use ultrasound studies to confirm and correlate the physiology/pathology of the gastrointestinal tract to the sounds heard during auscultation with stethoscopes.

Identify the relationships of dehydration and electrolyte depletion to ileus (decreased gut motility), the disease's risk factors, onset and progression of the disease, and best management practices for positive outcomes.

Evidence/explanation: Ileus, the likely origin of most endurance-related colics, is difficult to recognize, characterize, and treat. This fall, Drs. Schott and Holbrook would like to conduct an independent ultrasound pilot study to correlate gastrointestinal motility with sounds heard during auscultation with stethoscopes.

Concern #3: Endurance-related fatalities were frequently related to financial restraints of the owner/rider.

Solution: Riders "self-insure" against catastrophic injuries requiring non-ride-site hospitalization or surgery. Evidence/explanation: In 25% of the fatalities, referral to secondary-care facilities was declined or recommended surgery was declined. In one notable case, a horse with a large colon displacement was euthanized even though the surgeon quoted an 80% positive prognosis with surgery.

A fee of $3 per rider per ride would raise approximately $70,000 yearly. That amount could provide $5,000 to 12 horses to defray unexpected emergency off-site intensive veterinary care or surgery. This rider-supplied fund could, for example, pay up to $5,000 for advanced care/surgery after charges exceeded $1,500. Which horses would qualify, the level of the subsidy and plan administration remain details to be clarified.

Concern #4: Incomplete and/or inaccurate rider cards and veterinary information.

Solution: The Veterinary Committee could revise and standardize rider cards for 2011 to include body condition scores. Other suggestions:

Work to ensure time in and time to pulse are recorded and remainder of card completed.

Change to waterproof paper.

Develop a five-year plan for a single data entry system with possible web upload.

Evidence/explanation: Dr. Field­ing's rider card study and Dr. Holbrook's post-ride veterinary statistics study were hampered by inaccurate and incomplete reporting. Dr. Balch's mortality data analysis was hindered by incomplete fatality reports and absence of completed necropsy examinations.

While the task force recognizes that ride sites, challenging weather, difficult horses, and long hours are not conducive to completing paper work, completed and accurate written documents are vital and indispensable primary data for any additional analysis.

Concern #5: No follow-up information on pulls and treatments.

Solution: Collect information on 100s, which statistically have the most fatalities. This relatively small group of riders is highly motivated and would likely be cooperative.

Telephone all riders with equine pulls and treatments about their pre-ride (feed, electrolyte, hoof care, conditioning, transportation distance, etc.), ride (time to pulse, eating, drinking, electrolytes, speed, etc.), and post-ride (problem diagnosed, problem solved, problem continuing, etc.)

To use case-control studies, the same questions would be asked of successful riders immediately in front of and immediately behind pulls or treatments. Verification of data would be by trained observers at crew points.

A trial run at the December 19 Goethe Challenge 100 was proposed. The Research Committee, in conjunction with the Veterinary Committee, would formulate the survey. Research Committee members would do the telephoning. A report would be presented at the 2010 national convention.

A five-year plan would implement a web-based version of interview so that riders may independently fill out forms online.

Evidence/explanation: Little or no systematic information exists about pulls and treatments after horses leave ride camp. No analysis of risk factors exists for pulls and treatments that are not associated with fatalities. Since it is unreasonable to expect control judges or treatment veterinarians to collect such information during or after the ride, telephone interviews can be used to successfully collect information about pulls and treatments.

Conclusion

Years of mortality-data accumulation are finally providing a statistical basis for changes and benchmarks to judge accurately the success of new protocols. The AERC membership should be proud of its organization for its steadfast commitment to the welfare of the endurance horse.