CHRB's Postmordem Program Shapes Safety Initiatives

As racing gears horsemanship, regulatory efforts, and veterinary protocols—some using new technology—toward preventing catastrophic breakdowns in horses, the California Horse Racing Board's postmortem program at the University of California-Davis has been critical in developing the statistical information to shape those efforts.

Sue Stover, a professor at California-Davis who oversees the CHRB postmortem program, outlined information it has provided as well as advances based on that information during a webinar discussion that also included The Jockey Club steward for New York Racing Association tracks Jennifer Durenberger and Jamie Haydon, president of Grayson-Jockey Club Research Foundation.

Tuesday's webinar was the fourth in the series, which is taking the place of this year's canceled in-person Welfare and Safety of the Racehorse Summit.



Launched in 1990, Stover noted a key discovery of the program has been that pre-existing injuries are a key factor in catastrophic breakdowns. Other significant findings include information on hoof and horseshoe risk factors, racing surface studies, postmortem techniques, information on the management and prevention of injuries, the relation of jockey injuries with catastrophic horse injuries, the development of imaging techniques for enhancing ability to detect pre-existing lesions associated with an unrecoverable injury, and contributions to understanding of fracture development in bone.

"If I were to share two key findings throughout the postmortem program, it would be that catastrophic injuries are associated with pre-existing injuries. (Catastrophic injuries) are the acute manifestation of a more chronic process," Stover said. "Because these injuries are associated with the occupation of racing, they're occupational and tend to occur in these same configurations and same predictable locations."

Because of that predictability, Stover said the opportunity exists to identify affected horses that have the developing injury and to intervene in that period of time and prevent that catastrophic injury from happening.

Stover outlined some of the advancements made in identifying those smaller injuries.

In training Stover said it's important for each individual horse to receive the right amount of rest after work to allow bones to restructure and strengthen themselves. She said particular areas of concern are when a horse first begins training for racing and with veteran horses who have been asked to do a lot of racing and training.

Stover's study indicates that horses respond well to short exposures to high-intensity exercise and added high intensity work beyond that is not needed by the horse and risks causing the lesions that can lead to catastrophic injury.

She noted that close observation that allows for communication among everyone involved with the horse—the groom, vet, trainer, exercise rider—is a great defense in picking up smaller injuries that will require rest for the horse to recover and get stronger. She said that approach is important because each horse is an individual.

"The best answer is good horsemanship, good horsewomanship. It really takes a trainer who is paying attention to the attitude and performance of the horse, how the horse is doing, how it reacts to a certain event," Stover said. "Let's say we increase the intensity of training and the next day, or the next couple of days, the horse is just a bit off or doesn't want to walk out well. Those are very subtle signs that take an astute trainer who is paying attention to those things and sees that the horse needs more time to recover."

She later added that horsemanship involves, "the trainer, the groom, the veterinarian, all working together to understand how the horse is doing and progressing through the training program."

Being on top of those issues can prevent catastrophic injury.

"What we do know is that previous lameness is associated with catastrophic injury—not necessarily the lameness at the time that injury occurs but at some point in time in the previous three months," Stover said. "I think that's potentially related to when a focus of microdamage is initiated. When that horse has that microdamage and is stressed, it is initially painful. As it starts to resolve that microdamage, it might become less painful. But if a horse has had lameness, it's important to recognize that they're not just over whatever caused that lameness in a short period of time."

The postmortem program also has contributed to improved pre-race exams by regulatory vets. 

"Fortunately what we're able to do is increasing all the time," Durenberger said. "One of the reasons the necropsy program has been so valuable to the vets doing the pre-race inspections is that we do now know these predictable areas. We have the horse's history; what they've been doing. We know the number of high-speed furlongs. Are they coming off a layoff? Are they dropping in class? Are they stepping up? Have they run a bunch of races in the past month or are they coming to us off six months rest?

"So we can focus our exam on those areas where we might see these types of injuries."

Another time of added focus for a horse should be when they return off a layoff. In response to a question from the online audience, Stover noted that with horses coming back from varying breaks as a lot of tracks halted racing for COVID-19, some horses will need watchful eyes.

"We need to recognize that they could be at risk for some of these injuries because they are going to have to readapt the skeleton to racing and training," Stover said. "A lot of it will depend on what they were doing during this period of time. Were they still actively training? Were they still actively breezing? Or, were they put out to pasture or did they stall rest?

"Bone is very dynamic and if it can continue to see stresses associated with racing and training, these horses can continue on with their program. But if they were given more of a lay-up or inactivity, then caution needs to be taken for allowing them to readapt and rebuilding that skeleton for the rigors of racing."

Stover sees potential to reduce injury through new technology to examine horses before they race.

"We're making inroads on diagnostic techniques that are less expensive and more readily available. That may help pick up more horses with these problems," Stover said. "PET Scans certainly are opening up areas for identifying lesions, for example in the fetlock, that are not as accessible or visible on more routine diagnostic techniques. We'll be moving that forward in the future."

In using the technology, she said one area that will continue to need work is gathering information to identify the differences between problem areas and the natural process of bone restructuring.

"With any new technology, we need to understand what the findings mean," Stover said. "For example, with PET scan we can see hot spots in various regions. What we need to understand is which of those changes are adaptive, which of those changes can the horse recover from, and which of the changes put the horse at high risk for catastrophic injury if training or racing is continued."

Stover noted that necropsy programs added in other states also have made significant contributions to improving equine safety.

"While we were one of the first necropsy programs initiated to this level, there are certainly necropsy programs in other states that are also contributing to the database and it's really important to support them," Stover said.

Stover believes regulatory changes in recent years are adding protections for the horse. The 2019 equine fatality rate of 1.53 per 1,000 starts—99.85% of starts were safe—is the safest year on record in the 11 years The Jockey Club Equine Injury Database.

"The racing industry is making change in accord with what we've learned in the past and it's making an impact," Stover said. "These have been huge, multiple changes that have made an impact that have markedly reduced the rate of catastrophic injuries."