A new patented technique may help prevent some of the more serious complications of laminitis in affected horses.
Laminitis is a common debilitating condition of horses. The Lameness and Laminitis study carried out by the United States Department of Agriculture found that in a one-year period, 2% of horses are affected with laminitis. About 5% of affected horses die or are euthanized, and a further 20% suffer permanent damage.
Increased tension in the deep digital flexor tendon (DDFT) is implicated in the changes that occur within the foot.
Treatment of laminitis often includes trying to reduce the pull of the DDFT on the pedal bone. This may be by means of shoeing, or by cutting the tendon.
Dr Daniel W. Carter of West Florida Veterinary Associates, Gulf Breeze Florida, and Dr J Ben Renfroe of the Child Neurology Center of Northwest Florida have developed a new procedure to reduce tension in the DDFT.
The technique, which they described in the Journal of Equine Veterinary Science, involves injecting a diluted solution of Botox (Botulinum toxin type A) into the deep digital flexor muscle in several places. The skin is clipped and aseptically prepared before injection, and to make sure the muscle is injected correctly they monitor the procedure with an electromyograph (EMG).
They explain that botulinum toxin blocks the release of the neuro-transmitters (acetylcholine) from the nerve endings. This temporarily prevents the muscle contracting.
“ The clinical changes are first noted approximately two days later, with peak benefit in approximately two weeks.” The effects gradually wear off after about three months.
In the report, Carter and Renfroe describe several laminitis cases that they have treated using this technique. They feel that the technique has promise, so much so that they have patented it - so no one can use it without authorization.
“ Administering botulinum toxin type A in our hands was safe and effective for the treatment and prevention of laminitis” they conclude. “ Botulinum toxin chemically denervates the muscle belly, affecting the pull of the deep digital flexor tendon. The deep digital flexor muscle-tendon unit relaxes and decreases the pull on the palmar aspect of the distal phalanx, mimicking a deep digital flexor tenotomy.
The temporary nature of the botulinum toxin provides an intervention that is effective yet transient, therefore permitting the horse to return to a more normal routine after recovery from the laminitis.”
They suggest that further work, including controlled studies, should be carried out to further assess the value of the technique.
For more details see:
A novel approach to the treatment and prevention of laminitis: Botulinum Toxin Type A for the treatment of laminitis.
DW Carter, JB Renfroe.
J Equine Vet Sci (2009) 29, 595 - 600.