LEXINGTON, Ky. – Data collected through positron emission topographical [PET] scanning of racehorse limbs has begun to bear fruit in identifying horses that may be at high risk of a catastrophic injury of the fetlock or sesamoid bones, according to the administrator of a program at the University of California-Davis that has been using a new version of the machine to conduct lower-limb scans. Dr. Mathieu Spriet, an associate professor of surgical and radiological sciences at UC-Davis, said the experience he has gained examining 1,000 PET scans of fetlock joints has improved radiologists’ ability to monitor bone lesions and identify horses whose lesions are so severe that they should be laid up to heal. Spriet outlined his findings during a presentation Wednesday at the Welfare and Safety of the Racehorse Summit at the Keeneland sales pavilion. However, he also said that the scans routinely show evidence of lesions on approximately 20 percent of horses that are showing no clinical signs of lameness or gait abnormalities, making the use of the technology to “screen” horses for racing soundness problematic. “Obviously, we are not going to scratch 20 percent of the horses,” Spriet said. :: Get ready for Saratoga and Del Mar with a Quarterly subscription to DRF Past Performances Still, Spriet said that his own skepticism about the ability of the scans to identify at-risk horses has waned considerably as he has gained experience with using the scans and combining the data with other forms of imaging. In 2019, when the parent company of Santa Anita purchased a PET scanning machine designed for horses, Spriet was asked by the media whether he would be able to identify a horse that would “break down,” he said. “Back then, I said, no, it’s far too soon,” Spriet said. “Now, I am more comfortable answering that question.” PET scans use radioactive material injected into equine joints to create a three-dimensional map of the scanned area that highlights areas of the bone in which there is substantial remodeling activity. The scans are considered more useful in identifying severe areas of remodeling than any other existing scanning technology. However, PET scanning machines that existed prior to 2019 required horses to undergo general anesthesia in order to get a scan. After a rash of injuries at Santa Anita early in 2019 that drew widespread media attention, a manufacturer developed a model that could generate a scan on the lower limbs of a standing horse administered only a sedative, and the first was delivered to Santa Anita late in 2019. Spriet was on the “brainstorming” team that generated ideas on how to design and engineer the device, and he now collaborates widely with the racing industry on projects to explore the technology. There are now five of the machines currently in use, Spriet said, and five more that are being delivered to clients around the world. In total, according to Spriet, he has used the machines to conduct 1,000 scans of joints, including several hundred in a study that examined 72 horses based at Santa Anita, Golden Gate, and Fair Hill training center in Maryland. :: Bet the races on DRF Bets! Sign up with code WINNING to get a $250 Deposit Match, $10 Free Bet, and FREE DRF Formulator. All 72 horses selected for the study were not showing clinical signs of lameness, and all had finished in the top three of a race in the previous week. Not surprisingly, the horses showed far less evidence of lesions than horses who were selected for scans in earlier studies after showing clinical signs of lameness. Still, Spriet said, three of the horses in the study received recommendations of an extended lay-up, while the trainers of 15 of the horses were asked to “modify” their horses’ training regimens. The horses who were based at Golden Gate showed far less incidence and severity of bone lesions than the horses at Santa Anita and Fair Hill, Spriet said. Spriet noted that the horses included in the study at Golden Gate exclusively had raced or trained over the track's artificial racing surface. While Spriet said that he would caution against making a definitive soundness diagnosis from a PET scan showing low-grade lesions, he also said that the PET scans have more than proven their worth when being used to monitor the progress made by horses suffering from bone disease. “We see where we can check up on these horses that have been laid up, and that’s where we can really make a difference,” Spriet said.