Rarely has a racehorse practitioner not encountered a case of bucked shins (also called dorsal metacarpal disease, or DMD). This commonly identified racehorse injury has both mechanical and biologic roots, so one veterinarian recently set out to test a new treatment protocol in hopes of getting quicker and better results than current treatment options offer.
At the 2012 American Association of Equine Practitioners convention, held Dec. 1-5 in Anaheim, Calif., Ryan S. Carpenter, DVM, MS, Dipl. ACVS, a practitioner at Equine Medical Center in Cypress, Calif., described the results of a small trial he completed recently.
Bucked shins, Carpenter explained, are caused by "inadequate bone modeling and remodeling, resulting in fatigue failure" of the cannon bone; severe cases can result in stress fractures. Early signs of the condition include sensitivity to palpation; lameness only develops if the bone is overloaded continually during racing or training, he said. Stress fractures are identified via radiographs.
Currently, veterinarians recommend conservative management (i.e., stall rest) for horses with DMD that haven't developed fractures; more severely affected animals typically require surgery. However even with surgery, Carpenter said, success rates are variable, and it often takes eight or more months for horses to make their first post-injury start.
Recently, Carpenter tested a new treatment method--regional limb perfusion (RLP) with the bisphosphonate drug tiludronate plus extracorporeal shock wave therapy (ESWT)--on 10 racehorses (four males and six females) with DMD. He elected to use tiludronate because veterinarians have reported success treating other orthopedic conditions with the drug to slow down bone remodeling and restore normal balance between bone resorption and formation.
Investigators administered tiludronate RLP in the horses' affected leg(s) every other week during the six-week treatment protocol and treated the affected areas with ESWT weekly. Additionally, Carpenter devised an exercise program to accompany the treatment:
- Week 1: Hand walking, 10 minutes daily
- Week 2: Walking on the track under saddle, 15 minutes daily
- Week 3: Walking on the track under saddle, 25 minutes daily
- Week 4: Jogging on the track, 0.5 miles daily
- Week 5: Jogging on the track, 1 mile daily
- Week 6: Jogging on the track, 1.5 miles daily
"Currently, all 10 horses that have completed this protocol have raced successfully without recurrence," Carpenter said, noting that none of the horses developed complications from the tiludronate RLP. The average time from diagnosis to race return, he added, was 126 days.
Carpenter did note limitations to the current study:
- Because the treatments were used together, it was not clear which therapy was most important for treating DMD; and
- Only a small number of horses were included in the study.
"Since the success of the first 10 cases, several additional horses are currently being treated with this protocol, and subjectively the results are encouraging," he added. "It will be exciting to see what results are obtained when this protocol is conducted on a larger scale."
Carpenter noted that only after larger-scale studies are completed can "definitive recommendations be made regarding the proposed protocol" for widespread use in racehorses.
Disclaimer: Seek the advice of a qualified veterinarian before proceeding with any diagnosis, treatment, or therapy.