Please Remain Standing: New CT Scanner Changing The Landscape Of Equine Diagnostics

The following content has been originally authored by a Paulick Report contributor but is sponsored by AstoCT, the maker of this technology.

As any horse owner or trainer can attest, there are times when a horse that could talk would be beneficial—especially when it comes to determining exactly what is ailing them and where. When horse owners have exhausted the tools in their own repertoire, their first call is to a veterinarian.

A veterinarian will often begin with the basics to help determine exactly where the horse is hurting, running her hands over the horse’s legs and body, and performing a lameness exam. Once she has a general idea of where and what the issue is, she may take X-rays, use an ultrasound, or block a limb in specific areas to pinpoint the cause of the issue.

If those modalities fail, and moreover if the horse is an athlete tasked with performing a specific job — like racing or eventing — she may suggest other diagnostic options to help determine the root of the problem.

A Multitude of Modalities

The next diagnostic options generally include MRI, nuclear scintigraphy (“bone scans”), or computed tomography (CT) scans. While beneficial, each of these modalities has its limitations. The tool with the broadest application is a CT scan, which produces three-dimensional images. A CT scan can be used to detect changes to bone that might not be visible on X-rays as well as soft tissue structures. CT scans are often used to diagnose lameness issues (including occult and complex fractures), as well as sinus, head, and neck problems.

While helpful, these scans generally are not without risk. Traditional CT scans are performed on a fully anesthetized horse. The area needing to be scanned is then placed inside the machine while the horse is lying on a large gurney. The size of the opening of the machine limits how much of a horse can be scanned. Typically an adult horse can only be scanned up to his hock or knee.

However, horse owners now have another CT tool at their disposal that is fast, able to be used on additional body parts, and less fraught with possible complications: The Equina by Asto CT.

High-Tech Imaging

Developed at the University of Wisconsin-Madison, the Equina is the first dual-purpose standing CT. The machine can be used to vertically scan the lower legs and it can be used horizontally to scan the head and neck — all on a standing, sedated horse.

A horse stands on the target ring while awaiting a scan of the lower legs from the Equina system. Photo courtesy Asto CT

To scan the limbs, a horse is lead on to a platform at ground level and the limbs needing imaging are comfortably positioned within the “target ring.” At the press of a button, a circular structure rises from the platform and surrounds both front or hind legs. Unlike CT machines used in human medicine, which have limited capabilities on what they can scan, the entire opening of the Equina can produce a scan. This allows the horse to stand anywhere that is comfortable on the target ring to have his legs scanned.

Additionally, traditional machines produce large amounts of radiation, requiring the sedated horse to be in the room alone. The Equina machine, however, is self-shielded and emits exceptionally low levels of radiation. This allows veterinary staff to remain in the room with the horse and observe him closely, ensuring they are on hand to react rapidly if he needs help.

Dr. Sabrina Brounts, a professor in large animal surgery and equine sports medicine and rehabilitation at the University of Wisconsin-Madison, says that the entire process can take as little as 15 to 20 minutes. That includes getting the horse ready and sedated, scanning him and leading him back to his stall. The horse is typically sedated with acepromazine, detomidine, or xylazine. The scan itself takes less than a minute and if all goes well, a trained team can scan three to four horses an hour.

Brounts finds one of the Equina’s unique capabilities incredibly helpful: the CT can provide scans of  both limbs at the same time, regardless of if the horse is weight bearing or not.

“That gives you the information to compare both limbs [affected and unaffected] to find a cause for issues,” she explains. “The horse stands exactly like it normally does … If you had to scan one limb at a time, you would never be able to create the exact circumstances for the limbs.”

Benefits to Racehorses

Dr. Chris Whitton is the head of the U-Vet Equine Centre and lead researcher for the Equine Limb Injury Prevention Program at the University of Melbourne. Whitton is also an equine surgeon specialist and a researcher of subchondral bone injury in racehorses. For him, the biggest benefit he sees is the machine’s ability to find bone lesions that are missed on radiographs. This means that the machine could be used to identify and stave off injuries — potentially catastrophic ones — before they happen.

Dr Chris Whitton with the new CT Scanner at the Werribee Equine Centre on Sept. 5, 2019 in Werribee, Australia. (Pat Scala/Racing Photos)

The machine’s capability of comprehensively imaging bone and soft tissue of both limbs simultaneously is also a huge advantage, he notes. Racehorses in particular often present with bilateral injuries, and it’s not uncommon to observe additional lesions in the contralateral limb from the one that is lame.

Brounts relays that the Equina can also be used as a preventative measure to scan horses before they perform an athletic endeavor and as a pre-purchase tool. Currently, scans from the Equina may show some boney changes that vets are unable to be certain are clinically relevant or if they might cause a problem in the future, she said. This lack of knowledge highlights the need for collaboration between the equine industry and vets to determine what is “normal” and for ongoing research.

Ideally, this would allow veterinarians to create a database of findings and do a longitudinal study, following horses over time with multiple scans with and without injury, she says. That way, if a horse were to become injured, vets can look back at the previous scans and determine if they could have predicted the injury.

“Hospitals that have the same machines need to do research together to find answers,” Brounts explained. “Here, at the University of Wisconsin, we are in favor of such collaboration and are currently working with the University of Melbourne [and Dr. Whitton]  to try to find some answers.”

Drs. Whitton and Brounts see the use of the Equina machine going hand-in-hand with elevated attention to racehorse welfare.

“The Equina from Asto CT is so easy to use and horses tolerate it so nicely, it would be a huge asset for any racetrack [to use for] injury prevention,” Brounts said.

The limited time it takes to scan horses means that high numbers of horses can be imaged efficiently, added Whitton. He feels the limiting step to Equina use is the vet’s ability to read and interpret the large number of images generated.

Whitton already has plans in place to accentuate the racing industry’s dedication to equine welfare.

“We’re planning to do serial scans on horses in training to monitor changes in subchondral bone over time,” he said. “It would be logistically difficult to scan every horse before every race, but scanning horses regularly should be the goal.”

A horse is ready to undergo a scan of the head and neck thanks to the Equina system. Photo courtesy Asto CT

Whitton hopes to be able to rescan horses every three to six months.

Brounts seconds this, noting that as CT scanning becomes more available for horses with and without injuries, and as more research is done, veterinarians will have a better understanding of what changes are potentially serious and what changes are of an equine athlete and pose no harm.

“This [findings] will then guide us in using the CT scan as a preventive measure in the racing industry,” she said.

First and foremost, however, is the need for collaboration.

“It will be important to have all the players in the industry supportive of scanning horses for research purposes, as well as for diagnostic or preventive purposes,” she said.

The “industry” isn’t limited to just Thoroughbred racing, both veterinarians stress. The Equina has a place in the sport horse world as well. Whitton believes the machine can be useful for assessing foot conformation, examining suspensory ligaments and assessing pathology in hocks.

The need for multiple equine scans to create a baseline for sport horses is necessary, as well — and collaboration is again key: both between vets and between hospitals using the Equina. Whether the machine is being used to pinpoint existing lameness or to locate possible future injuries, the goal of the Equina is the same: to protect the equine athlete, whether he’s used for racing, competition or pleasure.

The post Please Remain Standing: New CT Scanner Changing The Landscape Of Equine Diagnostics appeared first on Horse Racing News | Paulick Report.

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