Developing a statistical picture of a race meet

Records for horses at Prairie Meadows provide a basis for evaluating safety and other mattersLive race meets at Prairie Meadows Racetrack and Casino in Altoona, Iowa, have had consistent lengths since 1993. While the future holds forth the promise of upward of 100 or more live racing days per year, there were 60 days of racing in 1993-'94, and 62 days of racing in 1995.
The similar length of the three recent live meets permits the comparison and analysis of official records kept on the horses during these meets. This analysis is one of many cooperative efforts taken to survey and improve the safety of horses and racing personnel. The Equine Safety Panel and its benefits were previously discussed (Thoroughbred Times, July 13), and future segments in this series will focus on horse injuries and the surveillance and maintenance of the racing surface.

Veterinary procedures
The race meets from 1993-'95 consisted of mixed Thoroughbred and Quarter Horse racing for each entire meet. On average, there were seven Thoroughbred and two Quarter Horse races per day. A medical record file was created for each horse registered to race at Prairie Meadows. In addition, a separate computer file was maintained and updated daily for current Coggins test information, bleeder/Lasix information, and current and past vet's list information.
A prerace soundness examination was performed on every horse the day of its scheduled race. The day's entries were roughly split in half by barn designation. To provide unbiased examinations, two state veterinarians alternated the "front-half barn area" or "back-half barn area" exams on a daily basis.
The prerace examination consisted of a tattoo identification check, general observation of a horse's attitude, removal of bandages, palpation of limbs, and an observation of the horse moving at a jog. The findings of these examinations were immediately recorded on the horse's medical record card. Each card thus allowed an evaluation of a horse's condition at any point, regardless of which examining veterinarian was the last to see a horse.
Following the morning prerace examinations, records for a current day's horses were reviewed and entered into the program to be carried by the "track surface" veterinarian. Additional entries were made on the medical records after each day's race card.
Shedrow examinations were also performed on horses following a race, depending on the way the horse ran, pulled up, came back to be unsaddled, and moved while in or going by the test barn. These exams and observations were also recorded on the medical cards. In addition, other recorded and unrecorded cursory exams were performed during training hours at the track, in the barn area, in the paddock, and on the track during racing.
A vet's list was maintained for scratched horses, bleeders, horses exhibiting soreness or lameness following a race, and other conditions. Horses placed on the vet's list for a musculoskeletal problem were required to perform well in a monitored morning workout and then pass a follow-up shedrow examination the following day before they were removed from the list and allowed to be entered in another race.

Yearly summary
The total number of Thoroughbreds registered to race at Prairie Meadows in 1995 was 951; in 1994, the number was 993; and, in 1993, 1,066. The 1995 population of registered Thoroughbreds represented a decrease from 1994 of approximately 4.2 % and from 1993 of approximately 10.8%. The comparison by age group of the 1995 horse population to the horse populations of 1993 and '94 is presented in Table 1. The relative and absolute number of registered younger Thoroughbreds decreased, while the relative and absolute number of older Thoroughbreds increased.
From the 951 Thoroughbreds at Prairie Meadows in 1995, 850 different Thoroughbreds made a total of 3,601 starts in 435 races. Field size averaged 8.3 Thoroughbreds per race in 1995, 8.0 Thoroughbreds per race in 1994, and 8.7 Thoroughbreds per race in 1993. The two-year-olds had approximately 71% of their registered numbers make an initial start in 1995. The other age groups had at least 85% of their registered numbers make at least one start in 1995. These numbers reflected relative increases in the percentage of registered Thoroughbreds that made at least one start for each age group when compared to 1994 and 1993 (Table 2).
In 1995, the average number of starts per Thoroughbred was 4.2. By age, the average number of starts was: 2.3 starts for two-year-olds; 3.6 for three-year-olds; 4.5 for four-year-olds; 4.8 for five-year-olds; 4.3 for six-year-olds; and 4.8 for seven-year-olds and older. The "mid-age" and older horses thus had more average starts as well as a higher percentage of starters.
Additional potentially pertinent information gleaned from the records for 1993-'95 included an increase in the number and percentage of Thoroughbreds that were entered to run on phenylbutazone and/or were administered Lasix. These percentages were:

	1993	1994	1995
Lasix	50.4%	59.3%	65.2%
Bute	90.5%	98.2%	97.3%

Summary
Injuries that prevent Thoroughbreds from racing cost the industry several hundred million dollars a year. There are many factors that contribute to the safety and longevity of Thoroughbreds in training and affect the number of Thoroughbreds able to withstand the rigors of training and racing.
Every jurisdiction develops a plan to identify, follow, and record important information that may turn out to be useful in minimizing time lost to racing and training injuries. By analyzing horse trends, in addition to other cooperative efforts, key factors important to the longevity of racing stock may be found.

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Brad J. Gordon, D.V.M., specializes in surgery, lameness, and therapeutics in the Midwest and Caribbean.