Researchers at the University of Edinburgh's Royal (Dick) Veterinary College in Scotland are turning to ancient medical traditions to help horses deals with the pain of laminitis.
Professor Sue Fleetwood-Walker, with researcher Rory Mitchell, is taking a clear, scientific look into Chinese and Greek traditions using mint to treat pain, in hopes that mint therapy might be key to the nerve-damage pain that is part of the complex response that horses have to the damage in their feet when laminitis strikes.
Previous research by Fleetwood-Walker, also conducted at Edinburgh and published in the journal Pain, chronicled evidence for a neuropathic component to the chronic pain state associated with equine laminitis, indicating that anti-neuropathic analgesic treatment may well have a role in the management of laminitic horses. In that study, electron micrographic analysis of the digital nerve of laminitic horses showed "peripheral nerve morphology to be abnormal, as well as having reduced numbers of unmyelinated (43.2%) and myelinated fibers (34.6%) compared to normal horses", according to the study's abstract.
Fleetwood-Walker has researched "phantom" pain in human amputation patients and also horn pain response in small mammals; her team discovered that cooling chemicals with the same properties as mint oil had powerful painkilling effects when applied in small doses to the skin.
The receptor molecule TRPM8 is responsible for the sensation of moderate cold and it has long been known that cooling eases pain. However, the Edinburgh researchers have shown that this receptor acts to induce a pathway of responses that ease the crippling effects of neuropathic chronic pain which is very different from the acute pain associated with direct trauma. Substances such as icilin or menthol, known activators of TRPM8 which mimics the sensation of cooling, may then be used to treat neuropathic chronic pain.
The compounds were likely to have minimal toxic side effects, being applied externally, and were likely to prove ideal for patients with chronic pain who found conventional painkillers ineffective. The next test is to find a way to test mint medications on horses with laminitis.
This research is funded by The Horse Trust, a leading British horse charity.