Study Of Inflammatory Markers Leaves Researchers With More Questions About Predicting Racehorse Injury

by | 09.14.2017 | 6:59pm

For years now, researchers have been searching for some kind of agent detectable in horses’ blood to warn them of an impending injury. Research presented by Dr. David Horohov of the Gluck Equine Research Center at the University of Kentucky at a recent Kentucky Equine Drug Research Council meeting shows the quest has continued to be a challenging one.

“The theory has been advanced that in fact, visible injury is a result of chronic accumulation of damage that exceeds the healing capacity of the tissue. And indeed, the whole process of conditioning an animal is actually one of breaking down and rebuilding tissue so that it’s stronger,” said Horohov. “If we could identify techniques to tell when that process has become imbalanced, where there is weakness rather than strength, we could begin identifying horses in advance.”

Initially, Horohov said scientists wanted to look for cytokines – biological message-carriers – associated with damage to bone and cartilage. This proved challenging because bones are constantly in a cycle of breaking down and building up in response to exercise. It is the remodeling process that prepares an equine (or human) skeleton to hold up to future impacts, based on past experience. This approach also did not seem sensitive enough and might miss other types of stress in the body, so Horohov set out to study the behavior of cytokines related to inflammation.

These messengers would be aware the body was recruiting inflammatory cells to deal with an injury but would not be involved in the inflammatory process themselves. Theoretically, he thought, low levels of inflammatory cytokines should indicate some degree of normal response to training, while high amounts might be a sign the body was not adjusting to the stress of training, increasing the likelihood of an accident.

Between 2015 and 2016, Horohov and his team studied two groups with a total of 130 horses over two years: one group, scattered across different trainers, at Keeneland‘s synthetic training track, and another group on a lighter workout program (working on turf once per week) on a nearby farm. The results were somewhat surprising.

Immediately after exercise, horses typically have an increase in inflammatory biomarkers, which come back down over time and usually go below their original level – thought to be a sign the horses’ tissues were adjusting to exercise. Horohov’s group did find a difference between the horses at the track and those trained on the farm – over time, horses training on the track saw their base level inflammatory index increase, rather than decrease.

“To us, this raises more questions than it answers,” he said.

Horohov said it was impossible to tell whether the increase in inflammatory index was a sign of an increased risk for injury, or if it was simply a normal response to training. Both groups of horses had just begun the process of breezing.

Horohov also hopes in the future, the study of inflammatory cytokines could be finessed to predict specific types of injuries.

Besides the somewhat puzzling results, studies like this one are challenging because in order to get a group of horses in a true racetrack setting, scientists must give up control of the horses’ environments. Across the group of 130 horses studied, many were with different trainers and different feeding programs (including different supplements); those on the farm were getting turnout, while those at the track were not. It’s difficult to draw broad conclusions when variables like these place horses in mini sub-groups.

“One of the problems, too, about sampling horses is they leave,” said Horohov. “You get something you’re really interested in, you go back and they’re not there anymore.”

Horohov estimated about 25 percent of horses came up with some kind of lameness during the study period, but they were split between so many different trainers and programs it was impossible to say with certainty whether their cytokine levels rose before their lamenesses, or when.

From here, Horohov’s team hopes to expand the study to try to minimize some of these variables and to see whether an exaggerated inflammatory response does, indeed, preempt injuries.

Study Suggests Need For Another Revision To Uniform Drug Guidelines

by | 09.14.2017 | 12:48pm

Recommended withdrawal guidelines for detomidine, commercially known as Dormosedan, may face review after a recent study suggested horses could test positive while adhering to the guidelines. The current guideline from the Racing Medication Testing Consortium suggests the threshold for a positive be set at 2ng/ml in urine and 1 ngl/ml in blood, with the recommended withdrawal for a 5 mg intravenous dose set at 48 hours.

Detomidine is a relatively short-acting sedative with some analgesic properties and may be used to reduce stress during medical procedures or travel, or in hospital settings.

Recently, the Kentucky Equine Drug Research Council funded a study to examine the behavior of a 20 mg dose (given intravenously or intramuscularly), which some veterinarians say is also used in the field, depending upon the situation.

For tests of the drug using a blood sample, a 20 mg dose was well below the recommended threshold by 48 hours post-administration; in some cases the drug was almost undetectable. In the case of urine tests for detomidine however, several samples were over the threshold at 48 hours.

 

 

Unfortunately, the study was designed to stop at 48 hours post-administration, and therefore did not shed light on whether extending the window to 72 hours would be sufficient to avoid accidental positive tests.

“The dose that was investigated initially was a 5 mg dose. A lot of our veterinarians use a 5 mg dose. Dr. [Andy] Roberts and some other veterinarians wanted to know if they could use a 20 mg dose. It’s going to give a bigger effect,” he said. “Very few of these substances that affect the central nervous system have a dose that’s fixed. It’s a dose range, and I think it’s a legitimate question on Dr. Roberts’ part about using that 20 mg dose.”

Sams, who is a member of the RMTC’s Scientific Advisory Committee, said these types of revisions are to be expected as more information comes to light about different drugs and their behavior in horses. Unfortunately, there is a disparity between the public’s thirst for uniform regulations and the amount of time (and money) it takes to complete studies like this one, which ultimately highlights the need for more research.

“The process was moving very slowly years ago and the RMTC came under enormous pressure to move forward and have thresholds for all of these substances that veterinarians had identified. The future of the RMTC, I think, was on the line at that point,” Sams remembered. “We made some less-than-optimal choices with regard to doses, but veterinarians were involved in every step of the way.”

How Old Is ‘Old’ For A Thoroughbred?

by | 07.06.2017 | 12:53pm

Gulch enjoying retirement at Old Friends Farm

Every year brings a handful of death announcements as stallions and broodmares succumb to “the infirmities of old age.” Whether the horse in question was in their early or late twenties, we usually get questions – doesn’t say, 25 years old sound young for a horse? And what exactly are the “infirmities of old age”?

Just as for people, there’s no hard and fast answer to the question of how long a horse can be expected to live. Generally speaking, ponies and miniature horses can live significantly longer than the average riding horse, and it’s not uncommon for them to reach their early or mid-thirties. Riding horses like Thoroughbreds and Quarter Horses begin to show their age in their late teens or early twenties, though may live well beyond that. The oldest horse in the history books, according to The Horse magazine, was Old Billy, a barge horse born in 1760 who lived to be 62. Old Billy is the exception rather than the rule, with most riding horses living to be between 20 and 30. Draft breeds, much like large dog breeds, usually have a slightly shorter lifespan due to their size.

“I figure once they get to be about thirty, every day is a gift,” said Dr. Bryan Waldridge of Park Equine Hospital.

Waldridge treats the residents of Old Friends in Georgetown, Ky., which always includes some number of geriatric Thoroughbreds. Unsurprisingly, Waldridge said, a horse’s life expectancy also has a lot to do with their health history. Horses coming off the racetrack with more wear-and-tear injuries may see those injuries flare into problematic arthritis more quickly and viciously than those that retired sound. Past illness can also leave a horse susceptible to complications later; a horse that has recovered from kidney disease may be more vulnerable years later to a recurrence, as is true for colic. There are also individual differences; some horses are more sensitive than others to environmental changes that could cause colic.

 

 

Waldridge also believes genetics and attitude have something to do with it.

“I think some people just genetically live longer and I think it’s true in horses,” said Waldridge. “Gulch looked like he was going to live forever until he got cancer and then it was over in no time. He was one of the oldest, toughest horses I ever saw.”

Gulch, a longtime resident of Old Friends, was euthanized in 2016 at the age of 32.

As with people, the death of an older horse can be the sum of one or more gradually worsening problems, rather than one, acute bout of illness (with the obvious exception of colic), hence the vague phrase “the infirmities of old age.” According to a study of deceased horses 15 years old and up from the University of Kentucky’s Veterinary Diagnostic Laboratory, the causes of death for most geriatric horses were disorders of the digestive system and those of the cardiovascular system. About half the cardiovascular cases were caused by a uterine artery rupture, which is considered one of the possible complications for broodmares 15 years of age and up. Most digestive issues likely manifested as colic, which is still the most common cause of death for all horses.

Fifteen years old is also recognized as the benchmark for increased risk of a certain type of intestinal lipoma, a fatty tumor, that can cause fatal colic. Colic generally gets more common with age, and risks associated with anesthesia become more serious as a horse ages, so surgeons are less inclined to operate on colic cases in their late teens and early twenties.

Cardiovascular issues become more common because with time, walls of the heart valves become thickened and the valves can sometimes fail to close properly, allowing blood to leak through the valves, which makes the heart work harder. Waldridge sees a fair number of deaths from congestive heart failure for this reason in older horses.

Aging grays are also at increased risk for skin cancer. It’s fairly common for gray horses to develop tumors on their faces, necks, or around the rectum. Most of those tumors are not problematic on their own but can pose challenges if they begin interfering with an organ’s function.

“Unlike humans and dogs, they don’t tend to be malignant in horses but where they are, they tend to cause trouble and they really like the hind end, so a horse can’t pass manure,” said Waldridge. “I’ve seen them get so big the horse couldn’t raise their tail to pass manure.”

A horse’s teeth, which are constantly erupting through their gums throughout their lives, may also begin to wear down or fall out as they age, making it more cumbersome to chew tough feedstuffs like dry hay or grain. Additionally, older horses struggle to maintain weight during periods of extreme cold, even when fed appropriate diets.

A horse with any level of athletic function is at risk for developing arthritis as they age, and this can progress to the point it interferes with a horse’s day-to-day function, especially if the horse is already dealing with other illnesses.

All this means owners and managers often must weigh an older horse’s “infirmities” with his quality of life.

“My definition that I always tell people is that when they can’t walk around and eat grass pain-free anymore, then to me, it’s time to think about euthanasia. If they can walk around and eat grass all right, they’re pretty happy,” said Waldridge, who emphasized a horse that lives to 23 is not necessarily receiving inferior care to one that lives to 30. “I think you can’t do anything about genetics. If they’ve had some serious problem in their past, it may ding them somewhere and make them where if they get an injury or illness in the same body system, it’ll hit them harder. It’s genetics and what’s happened to them their whole life leading up to that point, it doesn’t mean anyone’s done anything wrong.”

Eight Years After Its Creation, Equine Injury Database Shows Improvement In U.S. Racing

by  | 04.03.2017

The Paulick Report

 

The Equine Injury Database recently released data from 2016, showing the lowest fatality rate per 1,000 starts for American racehorses since the Database began keeping records in 2009. The fatality rate for 2016 was 1.54 per 1,000 starts and includes horses that died within 72 hours after a race. That figure is based on data from the racetracks holding 96 percent of race dates in the country. In those seven years of data collection, the rate of fatalities on dirt has gone down 19 percent, and turf racing has seen 44 percent fewer fatalities.

The Jockey Club announced the launch of the Database in 2008, at a time when the sport was scrambling to respond to public concerns about equine safety following the highly-publicized breakdown of Eight Belles at the 2008 Kentucky Derby. The hope was that the Database would identify patterns related to racing fatalities which could be used to make new rules for the protection of horses. Statistical models work more effectively the more data they have to draw on, so reform advocates knew the Database would take time to gather enough information to provide them with suggestions. In the meantime, equine medical directors, Jockey Club representatives, veterinarians, and others gathered to share their observations and safety concerns in their own jurisdictions.

The Database was one of the products of the Jockey Club’s Welfare and Safety of the Racehorse Summit, which was first held in October 2006. The Summit, together with findings from the Database, stimulated discussion about the need for safety and welfare rule reforms, and a range of new regulations have been adopted in major racing states as a result. The graphic below shows a selection of reform initiatives and their adoptions by major racing states, alongside fatality rates for corresponding years.

The challenge for regulators and statisticians working on and with the Database is not just trying to understand what racing is doing wrong; it’s also about figuring out what the sport has done right in its quest to bring the fatality rate down. 

Statistical Summary from 2009 to 2016
Calendar Year
2009 2010 2011 2012 2013 2014 2015 2016
Rate 2.00 1.88 1.88 1.92 1.90 1.89 1.62 1.54

 

There are so many factors influencing a horse’s likelihood of fatal injury that no one can be sure which of the Association of Racing Commissioners International model rules or other reforms has made the most difference in the rate’s downward trend.

“If there were just one thing we could fix, if there were a switch we could flip, we would have flipped it a long time ago,” said Dr. Mary Scollay, equine medical director for the Kentucky Horse Racing Commission and advisor on the Database. “It’s progress in inches, and I think the good news is that so far it has been inches in the right direction.”

The biggest milestones, according to Scollay? Whip regulation, which includes both rules requiring the “padded” or “popper” type whips designed to create noise more than impact, and restrictions on the number of times a jockey may hit a horse in succession. Those initiatives began around 2008 and continued as recently as last year, when California tightened its rules on whip use.

After learning toe grabs on front feet could predispose a horse to injury, several states began discussing shortening or banning the grabs altogether around 2009. Toe grabs on front feet have been made smaller in most major racing states. The Racing Surfaces Testing Laboratory, launched in 2009, has also provided important guidance to other labs on best practices for evaluating track surface.

Since 2012, states have begun changing the rules around claimed horses as well, reducing incentive for trainers to bring horses to the post with underlying issues. In California, claims are void by law if the horse dies during the race or is placed on the veterinarian’s list. Over the following two years, New York and Maryland added rules voiding claims in the event of death or a horse being vanned off.

EID timeline3

“Some people view the voided claim rule as some sort of warranty or protecting the claimant to the detriment of the trainer. It’s not about protecting people (other than the jockeys), it’s about protecting the horse,” said Scollay.

Scollay has studied injury statistics at high-level regional meets versus tracks with a more local trainer base. Perhaps counterintuitively, she found the smaller track with lots of claiming races had a lower fatality rate. She believes that’s because trainers there recognize the likelihood of bringing a claimer back to the barn after the race, and they don’t have a waiting list of horses to fill their stalls if they lost one to a major injury.

Scollay and Dr. Larry Bramlage, renowned equine orthopedic surgeon at Rood and Riddle Equine Hospital, both believe tougher corticosteroid regulation may have contributed to decreased fatalities. Although corticosteroids are not harmful in and of themselves, overuse can cloud a veterinarian’s ability to accurately assess a horse’s soundness. Methylprednisolone (also known as Depo-Medrol) was found to linger in the joints longer than other types of corticosteroids, which may be especially problematic.

depo medrolFor research purposes, Scollay routinely reviews Kentucky’s post-race drug testing data with “filters off,” meaning she sees all results from tests, including trace amounts of medications which aren’t considered violations. After new corticosteroid rules were enacted, she saw far fewer trace amounts of the drugs in horses’ systems. She’s also seen fewer commission-initiated scratches for unsoundness. The total number of scratches for the fiscal year 2013, prior to the current corticosteroid rules, was 146 at Kentucky’s tracks; in 2016, post-rule establishment, it was 101.

Outside of boosting state regulations, the number of racetracks using safety guidelines independent of state rules has increased, too. The NTRA launched its Safety and Integrity Alliance program in 2008 and had fifteen tracks accredited by 2009. There were 24 accredited by 2014.

Even with additional guidance from the database, Scollay recognizes it isn’t feasible for tracks to eliminate all risk factors for horses. Having a menu of suggested reforms does allow tracks to pick and choose areas they can control to reduce breakdowns.

Experts believe, for example, that running claiming horses for a significantly higher purse than their tag value (most commonly done at slots-fueled tracks) encourages risky behavior on the part of trainers. It may not be reasonable for a track to change its purse structure for fear of losing entries; instead, there could be other areas, like race distance, the track can try to adjust for minimal risk.

Hold your horses
It’s important to recognize it’s unlikely that any one rule change is responsible for the downturn in Thoroughbred deaths. Dr. Tim Parkin, veterinarian and epidemiologist from the University of Glasgow, said so far his team has been able to explain just 35 percent of the change in fatality rates with its statistical models. The remaining 65 percent of the rate reduction that hasn’t been quantified, and it may or may not be influenced by those regulatory changes.

Among the factors associated with 35 percent of the fatality rate decline: racing at two years old (horses are more likely to make their first starts at two, which is associated with reduced risk of injury), fewer races at six furlongs or under, fewer starts on dirt tracks not rated “fast,” and longer periods of time with the same trainer.

Parkin also cautions that it’s natural for rates like these to vary somewhat year to year, which is evident from 2011 to 2014, when the fatality rate fluctuated between 1.88 and 1.92 and back again. Statisticians use different formulas to determine whether a change between two numbers is “significant” or not likely due to natural variation. The drop from 2014 to 2015 was statistically significant; Parkin suspects the drop from 2015 to 2016 probably was not statistically significant.

“Given such a dramatic drop last year, I was anticipating that 2016 might see at least a leveling off or maybe a slight uptick,” he said. “Some of that drop might have been some natural variation. It wouldn’t have concerned me at all if there’d been a slight uptick in 2016 compared to the figures in 2015, but it’s further encouraging that there’s been a reduction. It gives me further confidence that what we’re seeing is a true reduction.”

Dr. Tim Parkin

Parkin said the Database continues to collect additional types of data from racetracks to help analysts interpret the numbers. Workout data is now being added into the Database, which Parkin hopes will help give him more clues about the relationship of rest periods to injury rates; it’s generally believed that too-long of a rest has a negative impact on bone remodeling, but that hasn’t been testable to this point. One major dark area for Database analysts remains the veterinary records of horses that break down, as information is still subject to state privacy laws. It’s also challenging to incorporate race-by-race changes in track surface due to weather, although the Database has recorded a track’s official condition at the time of a race and found (unsurprisingly) that fast or firm tracks had less likelihood of fatal breakdowns.

As the industry continues to learn more, Parkin believes the simple discussion of these risk factors in the media and between regulators is probably having an unmeasurable impact.

“It’s undoubtedly the case that simply talking about the issue gets people thinking about it,” he said. “I’ve seen lots of vets at their own tracks that have spoken to me and said, ‘We’re thinking about this and I keep my own spreadsheet of what’s going on.’ That’s probably something they wouldn’t have been doing 10 years ago. It’s kind of an attitudinal change, as well as other, more measurable changes.”

Parkin said The Jockey Club recently renewed funding for the upkeep and analysis of the Database. In the future, he’s hoping to create models that will test the impact of rule changes over the years since their institution.

Although there’s still a lot to learn and much work to be done, Scollay said she’s proud of how far the industry has come in working to improve equine safety.

“When you look at 2009 to 2016, I get chills,” she said. “What we needed to do, and what we talked about at the first Welfare and Safety Summit, was reducing our race fatalities by 50 percent. If we do that, the rest of the world has to talk to us like grown-ups, so we’ll be there with them. Then [the fatality rate] will become all of our problem, not just, ‘Those Americans who can’t do it right.’ It’ll be a communal problem we have to continue to work on, but the finger pointing stops.

“We’re halfway there. I think people should be heartened by that, but not get complacent. For people saying, ‘it’s a part of the game,’ it’s less a part of the game than you think. So I’m thrilled.”