Pulse - March 2021 - 20

UC DAVIS UPDATE

UC Davis PET Scan Research Put
to the Test at Santa Anita
Rob Warren, UC Davis VMTH Communications & Marketing Officer

t has now been more than one year since Santa
Anita Park installed the world's first positron
emission tomography (PET) scanner specifically
designed to image standing racehorses. This installation, one of several measures to reduce breakdowns
at the racetrack, received a lot of attention at a time
when Santa Anita was just coming out of a challenging racing season, with a cluster of horse fatalities
early in the previous year.
The Stronach Group, owner of Santa Anita, invested in
equine PET following the promising pilot work led by radiologist Dr. Mathieu Spriet at the UC Davis School of Veterinary
Medicine. Over the previous four years, the UC Davis team
demonstrated that PET could detect abnormal changes in
bones of racehorses, which were not seen with other imaging
modalities. This initial work, however, required horses to be
laying down under general anesthesia, a major barrier to common use at a racetrack. Inspired by success of the early studies,
LONGMILE Veterinary Imaging developed the MILE-PET
scanner for safe imaging of standing, lightly sedated horses.
Since installation, Santa Anita has conducted nearly 200
successful PET studies on more than 100 different horses,
with many horses imaged multiple times, to follow the evolution of bone changes over time.
The MILE-PET scanner performed robustly, without a single down day. About half of the PET scans were part of sponsored research projects, while the other half were requested by
racetrack veterinarians for specific assessment of horses under
their care.
One of the research projects, sponsored by Grayson Jockey
Club Research Foundation, allowed comparing findings of
PET scan with those of nuclear scintigraphy, an imaging technology that has been pioneered and used at Santa Anita for
more than 20 years. The fetlocks of 32 horses were imaged
with both modalities, and the data were independently analyzed by a group of seven different observers including racetrack veterinarians and UC Davis researchers. The results
showed that veterinarians were able to more consistently
detect and better characterize abnormalities on PET scans
than on bone scans. This was particularly true for abnormalities involving the sesamoid bones, which are commonly
involved in catastrophic fetlock fractures.
In a second part of the Grayson Jockey Club Research
Foundation study, 24 horses were followed over time, with
scans repeated at 6 and 12 weeks after the initial scan. This
project determined how quickly abnormalities might improve
over time in horses resting from training. Preliminary results

The MILE-PET scanner in use at Santa Anita on the hind fetlock of a racehorse.

demonstrated that some abnormalities respond positively to
rest quickly, whereas others are more problematic and require
a longer time for healing.
" We have learned a lot through these different projects, "
said Dr. Spriet. " We recognize a few common patterns, but
each horse is different. "
PET has established itself as a reliable and helpful diagnostic
tool at the racetrack, but there is still a lot more to learn. An
upcoming project will use PET to look at horses performing well, thus helping to distinguish between normal adaptation to training and developing injury. PET will also be used
to scan horses with repaired fractures, to assess existing injuries that might have led to the fractures and to monitor bone
healing. PET innovation and success at Santa Anita inspired
the installation of a standing PET scanner on the East Coast,
at the New Bolton Center at the University of Pennsylvania.
Further, with support from the UC Davis Center for Equine
Health and the Stronach Group, a MILE-PET scanner will be
installed at the UC Davis veterinary hospital in early 2021,
making this technology available for racehorses in Northern California. The availability of these scanners at multiple
sites will enable comparing injuries on different racetracks,
improving understanding of possible causes for injuries, and
helping further prevention of breakdowns. P

" We have learned a lot through these
different projects, " said Dr. Spriet.
" We recognize a few common patterns,
but each horse is different. "
MARCH 2021

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Pulse - March 2021

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