Putting laminitis on ice

Also described as digital hypothermia, cryotherapy involves submerging an affected horse’s limb and foot in ice and cooling them to four degrees Celsius.

“[There’s] quite a bit of evidence that icing the feet is an effective way to prevent laminitis in horses that are at risk, and there is some evidence that it helps in treating acute laminitis,” says Dr. Julia Montgomery, an associate professor in the WCVM’s Department of Large Animal Clinical Sciences and the study’s lead investigator.

Laminitis is a condition that affects the tissues (laminae) that bind the equine coffin bone to the hoof wall. The disease can quickly progress into lameness as the coffin bone shifts away from the hoof wall. If left untreated, laminitis can lead to an excruciatingly painful end to a horse’s career.

Although there’s limited understanding of the exact mechanism that makes cryotherapy work, the treatment has proven to be effective at slowing the progression of laminitis and providing pain relief.

Since there’s no definitive cure for laminitis, some equine researchers are focusing their efforts on preventing this debilitating equine disease. Using data from previous research studies, the WCVM researchers aim to develop a prototype that introduces a water cycling system into a boot or sleeve-style device that will make cryotherapy easier in both clinical and public settings.

Current cryotherapy methods include commercially-available ice boots, ice water slurries, ice packs and gel packs that present their own issues such as the need to constantly monitor temperature, exchange ice packs or refill ice. Although dry cryotherapy is also a treatment option, it can involve direct contact between the ice and the leg that may cause cold thermal injuries after prolonged use.

With their focus on a device that avoids direct contact and limits the labour required for maintaining the treatment, the WCVM team is collaborating with RMD Engineering Inc., a Saskatoon-based engineering consulting firm, on initial designs with plans to begin testing the device in 2022.

“I’ve worked with engineers in the past, and I’ve really learned to value this collaboration because we take different perspectives looking at a problem and work together on a solution,” says Montgomery.

Using their unique perspectives, the researchers and the engineers will determine the mechanisms of the prototype while considering what will and will not work when dealing with horses. 

For example, the research team will consider issues such as the height at which the leg should be iced. This detail is important because the blood flow in a horse’s leg constantly circulates warm blood down into the hoof, potentially counteracting the treatment. Icing farther up the horse’s limb can solve that problem by decreasing the temperature of the blood before it reaches the hoof.

Another correlation that researchers must also consider is the temperature of the horse’s hoof, which should be included in the icing mechanism. Since the surface of the hoof has direct contact with ice, its temperature will be a couple of degrees cooler than the inside of the foot, the primary target for cryotherapy. 

Although there’s limited understanding of the exact mechanism that makes cryotherapy work, the treatment has proven to be effective at slowing the progression of laminitis and providing pain relief.

Until researchers can understand the pathology of laminitis well enough to develop a cure for this devastating disease, Montgomery emphasizes the importance of prevention.

“Be aware of some of the conditions that really put [the horses] at risk because once laminitis happens even with all the medicine and technology we have, we are still very limited in what we can do to prevent some of the severe changes that can happen,” says Montgomery.

Jazlynn Lewis of Bandera, Texas, is a third-year student (animal science) at Angelo State University whose WCVM summer research position is supported by the Fulbright Canada-MITACS Globalink Program. Her story is part of a series of articles written by WCVM summer research students.