Monday, February 11, 2008

New Treatment for Pain of Lam-"Mint"-Itis?

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.


suebroux said...

I find this study fascinating as I have maintained a small and not-so-scientific amount of information on neuropathy in humans.

Here's an interesting related tidbit - the application of Listerine (of all things!) used externally on patients suffering from neuropathy in their limbs is actually soothing and comforting. And to think that a mouthwash that "kills germs and freshens breath" has the ability to activate receptor molecules to ease chronic pain.

Fran Jurga said...

Thanks very much for your interesting comment, Sue. It is interesting on several fronts!

First of all, the Listerine connection to pain relief is one I certainly am not qualified to comment on, but I think it is interesting that Listerine is owned by Pfizer, and Pfizer has had such great success with the relatively new medication Lyrica (pregabalin) for peripheral (i.e. digital extremity) nerve pain. I wonder if they are aware of the success that you attribute to their mouthwash!

Second, I often see Listerine in the tack rooms of horse farms,but not for pain treatment. It is widely believed to be a useful medication/disinfectant for rain rot (fungal skin problem) and scratches (pastern dermatitis) in horses.

I love to keep track of home remedies for hoof problems. Danny Ward and I came up with a medicine cabinet kit for hoof problems--Listerine for scratches, toothpaste (I can't remember which brand but it was whitening formula) for thrush, and Efferdent for soaking the foot to completely clean it before treating the white line, also with toothpaste. The Efferdent was suggested by farrier Victor Camp of Lexington, Kentucky. Adolph's meat tenderizer for proud flesh is another one, but I have been told by vets that that one is way too far out.

Fran Jurga said...

PS I know what the next comment will be so let me answer it: no, I do not know if Lyrica has been used on horses with laminitis to alleviate peripheral nerve pain associated with the type of damage described by the Scottish researchers. As far as I know (and that is not much), Lyrica is only approved for human use.

Scott said...

Hi Fran,

Thanks for the great post. It's great to see studies done with natural methods.


BTW - I've "Nickered" your post at to let other equestrians find it.