RACE HORSE WELFARE REFORMS LONG OVERDUE
By Dr. Michael W. Fox
Dr David William’s letter inquiring “Should we continue to tolerate racehorse deaths” (1) calls for some reflection and documentation offered herewith: Mattison’s article about the racetrack-led coalition to address horse racing deaths and safety concerns in the U.S. (2) clearly identifies the veterinarian’s role and responsibilities with regard to medications widely used to enhance performance and treating racing injury-related pain and inflammation.
The inclusion of the U.S. Jockey Club’s Equine Injury Database numbers in this article gives some insight into the prevalence of injuries. It is notable that between 2009-2015 for horses raced at 2 years of age there were 366 fatal injuries representing 1.37% per thousand horses raced at this age. During this same time-period there were 122 fatal injuries representing 1.79% per thousand 3-year old horses raced; and for 4-year old horses there were 4,013 fatal injuries representing 1.86% of every 1,000 horses raced. This would seem to indicate the cumulative adverse effects of racing with increasing age leading ultimately to fatality. What would be the fatal injury rate in horses given optimal conditioning but not raced until 3 or 4 years of age?
That horses are raced as young as 2 years of age in many countries may be based on the findings that tendon injuries heal faster in young horses (3). The authors of this study conclude: “An hypothesis is advanced that immature tendon can respond to exercise while mature tendon has limited, if any, ability to do so. These findings support potentially controversial earlier conditioning and racing of younger, rather than older, equine athletes.” This study seems to give implicit sanction to race horses competitively at 2 years of age when they are some years away from full skeletal maturity. But on what basis beyond costs of care has the consensus been reached that it is acceptable to race horses— almost at full body weight/musculature but still relatively immature in skeletal structure, bone density and in terms of incomplete epiphyseal closure— at 24 months of age, individual differences notwithstanding?
Growth plate closure of Thoroughbred horses (mean 756.3 days) was reported to be significantly shorter than in Anglo-Arabians. Within each breed metaphyseal growth plate closed earlier in fillies than in colts but only in Thoroughbreds the statistical differences were significant (4). In another study the average age of closure of the distal radial physes was 29.8 +/- 1.6 months, with age of closure ranging from 26 to 35 months. A significant relationship was not found between physeal classification and the incidence of injury. The number of injuries was also found not to be related to the number of races, number of races won, money won, or to the fastest mile. There was a weak indication that horses with physes classified as C or B- (very immature) may not have raced quite as well as the more mature horses and may have had a slightly higher incidence of injury (5).
Another study concluded that most of the physeal closures took place between sixteen and twenty-four months of age. Arbitrarily, it was decided that a horse might withstand the rigors of the training period with less stress damage if training was deferred until the epiphyseal closure of the tuber calcis was complete (6). A similar conclusion was drawn in yet another study that distal radial physeal closure time was sooner in females than males, and took 701 +/- 37 and 748 +/- 55 days respectively (7).
From these determinations it would seem that with appropriate exercise/conditioning and optimal nutrition and husbandry and not being raced competitively until 3.5-4 years of age these magnificent animals might suffer fewer fatalities on the race track and injuries that take them from the track to the slaughterhouse (8).This assertion is clearly articulated in a study of race records in the U.K. finding that 327 (61%) of the 2‐year‐olds in training competed one or more times, 95 (18%) won and 165 (31%) were placed. Only 28 (5%) earned enough prize money to cover their training fees. Sore shins and inflammatory airway disease (IAD) were the two ailments most commonly encountered. In 2002, 431 (80%) of the previous year’s 2‐year‐olds remained in training aged 3 years and 25 entered training having not raced previously. Of the 456 3‐year‐olds in training, 347 (76%) raced one or more times 138 (30%) won, 218 (48%) were placed and 78 (17%) recouped their training fees. Joint problems and sore shins were the ailments most commonly suffered and, with the exception of rhabdomyolysis (‘tying up’), colts and geldings suffered a higher rate of musculoskeletal injuries than fillies. The authors concluded: Previous reports of high non-run and nonplaced rates, high incidence of injury and cost‐ineffectiveness of 2‐year‐olds in flat‐race training were confirmed (9).
The U.S. Jockey Club’s Vision 2025 report gives no mention of at what age Thoroughbreds should be raced competitively (10) although some races like the Kentucky Derby are restricted to 3-year- old only. In a study of age-related racing performance it was found that a typical horse’s peak racing age is 4.45 years. The rate of improvement from age 2 to 4 1⁄2 is greater than the rate of decline after age 4 1⁄2. A typical horse will improve by 10 (horse) lengths in sprints (less than 1 mile) and 15 lengths in routes (one mile or greater) from age 2 to 4 1⁄2. Over the next five years the typical decline is 6 lengths for sprints and 9 1⁄2 lengths for routes (11).
In another study speed increased up until the first half of the age of 4 years old. The effect of increased carry weight on average speed was small, and average speed increased with the growth of the horse. After the latter half of the age of 4 years old, the horses’ average speed remained almost constant, with little variation (12) A more ambiguous conclusion was drawn from another study reporting that two‐year‐old training milestones had a strong association with positive racing career outcomes. Horses in training or racing as 2‐year‐olds may have better musculoskeletal health throughout life than horses that are first in training or racing at a later age (13). However, in this study the failure of 32.7% (1531⁄4683) of horses to reach the first training milestone of being registered with a trainer implies a high percentage of wastage.
Inadequate training and conditioning of young Thoroughbreds once rectified can reduce the incidence of race-related injuries and deaths. With training of greater intensity, adaptive change is supervened by patho-anatomical change in the form of microdamage and frank lesions. Early training may be associated with greater thickness of hyaline but not calcified articular cartilage, at least in some sites.
The age at which adaptation of cartilage to biomechanical influences can occur may thus extend beyond very early life. However, cartilage appears to be the most susceptible of the three tissues to pathological alteration. The effect of training exercise on the anatomical or patho-anatomical features of connective tissue structures is affected by the timing, type and amount of natural or imposed exercise during growth and development which precedes the training (14).
One significant study supports the feasibility of imposing early conditioning exercise in horses and is a benchmark for its effects on the development of equine musculoskeletal tissues (15). All but two of 23 horses that died at Santa Anita racetrack over a three-month period appear to have had existing injuries caused by high-intensity racing and training before suffering catastrophic injuries to the fetlock, according to the results of a California Horse Racing Board investigation. (16) Anti-inflammatory medications likely compromised prerace examinations; lesions that could have signaled a potential break were not easily detected; and most of the trainers lacked an understanding of anatomy and the significance of major lesions, the report says.
Considering the above findings with regard to skeletal maturation and cumulative injuries over time when raced at 2 years a distinction should be made between training and competitive racing for 2-year- olds. The evidence of the benefits of training and not racing until more mature are supported by the findings cited in this review the optimal age being around 3.5-4 years.
TIME TO STOP DRUGGING RACE HORSES
It is shocking that the drugging of race horses with furosemide (Salix, Lasix) is done routinely to help prevent bleeding in horses suffering from EIPH (Exercise Induced Pulmonary Hemorrhage). Their extreme and sustained exertion causes them to literally burst their lungs and even suffocate in their own blood. Horses given this diuretic medication, which can cause dehydration and electrolyte imbalances, along with decreased levels of blood potassium and calcium, may simply collapse, often fracturing one or more bones in the process-and be slaughtered. Both of these electrolytes are important in normal functioning of heart and skeletal musculature.
In a posting from https://veterinarypartner.vin.com/ Phenylbutazone and Fatal Injuries in Thoroughbred RacehorsesBob Judd, DVM, DABVP (Equine Medicine), DABVP (Canine and Feline Practice) Courtesy of Texas Farm Bureau Radio Network Date Published: 06/17/2021
“A recent paper out of Argentina examined the use of phenylbutazone, commonly called bute, and the risk of musculoskeletal and fatal injuries in thoroughbred racehorses. Phenylbutazone is an anti-inflammatory medication that reduces pain and inflammation in horses, and at this point it is not a prohibited substance in the horse’s blood while racing in the United States.
However, the last dose of bute can be given no less than 48 hours before the race and a maximum small amount of the drug is allowed in the horse’s system after a race. In a study recently published in the AVMA Journal out of Argentina on almost 300,000 race starts, horses that recently received bute were identified as being at a significantly increased risk of musculoskeletal injuries leading to fatalities.
The fatalities occurred not from the drug but from injuries received while racing that required euthanasia, and horses given bute before the race were twice as likely to have an injury that led to euthanasia. The study’s authors believe that many horses given bute are older ones with chronic disease that may increase their chances of injury. Also, the horses given bute are painful and lame to some degree as this is the reason they need bute to compete. Bute decreases pain and allows the horses to potentially run faster and increases the chance they can hurt themselves by taking away the pain.”
For more details on the drug use by the racehorse industry see https://www.nationalgeographic.com/animals/article/racehorse-doping-explained along with efforts to “regulate.”
A new study of data from the Equine Injury Database has revealed that horses medicated with furosemide (Lasix) on race day were at 62 percent increased odds of sudden death compared to horses that were not racing on furosemide. (https://doi.org/10.2460/javma.22.08.0358).
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10.The Jockey Club. Vision 2025. To Prosper, Horse Racing Needs Comprehensive Reform. March 28th 2019 http://jockeyclub.com/pdfs/vision_2025.pdf Accessed Feb 2nd 2020
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13.Tanner JC, Rogers CW, and Firth EC (2013), The association of 2-year old training milestones with career length and racing success in a sample of Thoroughbred horses in New Zealand. Equine Vet J 2011;45: 20-24.
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15.Henry, J. No illegal medications found in state’s investigation into horse deaths at Santa Anita. Report finds all but two of the 23 horses that died were believed to have had preexisting injuries caused by high-intensity racing, training Pasadena Star News, March 10th 2020