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One topic that was met with great interest at the North American Veterinary Conference (January 2016) was therapy for laminitis. Vernon C. Dryden, DVM, CJF, APF, of Rood and Riddle Equine Hospital in Lexington, Kentucky, approached this subject from several angles. We will run a series of articles based on his presentations on EquiManagement.com.
Treating Laminitis with Stem Cells
Managing laminitis cases is an inevitable part of equine veterinary practice. Many different therapies have been tried, each working to a lesser or greater degree depending on the case. As explained by Dryden, a newer adjunctive therapy is the use of stem cells.
When laminitis results in detachment of the dermal-interdermal interface, there is a potential for pedal bone displacement, either with rotation or sinking. As the tissue heals, it forms a lamellar wedge. Dryden reported that success of laminar stability is inversely proportional to the thickness of the lamellar wedge. Lamellar wedge and epidermal cell hyperplasia are known to occur within 30 days of pedal bone displacement.
The attempt with mesenchymal stem cell (MSC) therapy is to manage lamellar tissue quality as it heals and also to gain palliative anti-inflammatory effects elicited by MSC. A trial using MSC was conducted on 30 horses experiencing serious laminitis. The horses treated were affected by either a) severe rotation with possible mild to moderate bone disease; b) chronic laminitis with severe bone disease; or c) sinking. Treatment was given monthly for 3-4 administrations, and treatment was administered using retrograde digital limb perfusion at the level of the palmar/plantar digital vein.
The results were encouraging: 70% (21 of 30) overall had successful results. Deep digital flexor tenotomy was performed on at least one limb in half the horses, in many cases because they were sinkers.
Of significance is that horses receiving MSC treatment within 30 days of the acute onset of laminitis had a 100% favorable outcome. In contrast, only 50% of horses receiving MSC treatment beyond 90 days from onset of laminitis experienced success. In general, if a horse was treated with MSC prior to 71.5 days, 87% were successful. If the first treatment was begun past 71.5 days, then 53% were successful. In addition, horses younger than 11 years seemed to have a better outcomes than older individuals.
The other significant finding was that horses with severe bone disease did not achieve a successful outcome, but 59% of those with mild to moderate bone disease did. The study reported: “In chronic advanced cases with bone disease and lamellar wedge formation, MSC therapy had no effect on prognosis” because the lamellar wedge had already formed. Sinkers appeared to respond the most dramatically to MSC therapy, with 18 sinkers achieving favorable improvement with MSC treatment applied within the recommended time period.