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Successful use of allogenic umbilical cord-derived stem cellsin nonresponsive chronic laminitic cases

Scott Morrison DVMRood and Riddle Equine Hospital, Lexington KY

Take-Home Message: Stem cell therapy, using equine umbilicalcord-derived cells, can improve the success rate in horses withchronic refractory laminitis, when used in conjunction withroutine treatment procedures and hoof support systems. The cellsare delivered directly to the affected foot via regional perfusionusing a digital vein.

Introduction: Many chronic laminitis cases can be rehabilitatedto various degrees of stability or soundness. Foot support systems,deep digital flexor tenotomy, and hoof wall resection arecommonly used in unstable cases. Success rates for various formsof chronic unstable/uncompensated laminitis have been docu-mented for our caseload and treatment approach (Morrison,2009). With success rates already established, we were able tobegin studying whether the addition of stem cell therapy couldimprove our success rates.Materials and Methods: Outcome data were reviewed for 12horses with chronic laminitis that were unresponsive to all othertreatments and thus were treated with stem cells. In all cases,routine treatment for laminitis continued and variously includedantibiotic therapy, foot casts, deep flexor tenotomy, hoof wallresection, and anti-inflammatory therapy.The stem cells were derived from equine umbilical cord blood,and an estimated 20–25 million cells were administered to eachaffected foot. The cells were diluted in sterile saline and infusedinto a digital vein using a technique similar to that described forregional perfusion of antibiotics in horses. Immediately followingstem cell infusion, the tourniquet was left in place for 25–30 minand the limb intermittently unweighted to facilitate distributionof stem cells to all regions of the foot. The procedurewas repeatedevery 3–4 weeks as needed.Results: To date 10/12 horses (83%) are doing well. However,long-term success rates still need to be determined. The first“successful” case is only 14 months out from initial treatment. Onaverage, 3 stem cell infusions were administered per affected foot.Discussion and Conclusions: Stem cell therapy improved thesuccess rate in this group of refractory laminitis cases. Althoughstem cell therapy potentially is a useful adjunctive treatment tohelp rehabilitate severe cases, it is important to note that othertreatment modalities must also be in place for a successfuloutcome. Timing of treatment, route of administration, andhistological studies of the tissue type generated after stem celltherapy are areas that need further investigation.

Practical – Laminitis: Progress by Design

Metabolic intervention: recognizing and acting on the subtleearly warning signs of insulin resistance

Donald M. Walsh DVMHomestead Veterinary Hospital, Pacific MO

Take-Home Message: Hyperinsulinemia causes changes in hoofgrowth that are easily detectable by hoof caregivers and veteri-narians. Intervention which normalizes blood insulin concentra-tions can prevent laminitis and restore a normal hoof growthpattern.Introduction: Insulin resistance that results in hyperinsulinemiais associated with laminitis in horses and ponies. The exactmechanism is still under investigation, but recent work hasshown that insulin may be activating insulin-like growth factor 1receptors on epidermal laminar cells. The result is an abnormalproliferation of epidermal cells in the laminae. In the hyper-insulinemic model of laminitis, this proliferation causes thelaminae to lengthen and stretch. These same changes are seen inprelaminitic animals that are experiencing abnormally highinsulin levels associated with equine metabolic syndrome orequine Cushing's disease.

Identifying At-Risk Individuals: It is important to appreciatethat even animals with no history of lameness may haveabnormal hoof growth patterns related to elevated blood insulinlevels. (Normal fasting blood insulin levels are considered to be10–40 mU/ml.) If hyperinsulinemia is not addressed and bloodinsulin levels normalized, then continued abnormal hoof growthmay lead to further weakening of the laminae and the develop-ment of laminitis. However, in cases where diet, exercise, andappropriate medication are able to normalize the insulin levels,over time hoof growth returns to normal and laminitis is averted.Abnormal growth rings in the external hoof wall and separationof the wall from thewhite line, with the presence of seedy toe, areearly signs of the damaging effects of hyperinsulinemia. Often,small areas of hemorrhage are present in the seedy-toe area,caused by damage to the laminar vessels. These changes slowlyprogress if hyperinsulinemia persists until the laminae can nolonger effectively suspend the distal phalanx in its normal posi-tion; consequently, the distal phalanx descends into the sole andthe horse now has acute laminitis. This final insult is caused byvery elevated insulin levels, often associated with the intake ofa high nonstructural carbohydrate diet, such as spring grasses.These cases are usually confined off the pasture and treated withpain medication. However, the initial clinical response is