Equine non-infectious synovitis associated with osteoarthritis can be devastating to both the horse and owner. It can also
be difficult for the equine practitioner to treat. Early detection and treatment are the cornerstones of successful management
of osteoarthritis, and hyaluronate sodium is an important part of that treatment.
Hyaluronate sodium (hyaluronic acid) is a normal joint fluid and cartilage component. It decreases production of the mediators
of inflammation within the joint. Hyaluronic acid also lubricates and protects the joint cartilage and synovial membrane.2 Legend® (hyaluronate sodium) Injectable Solution (Bayer Animal Health) is produced by a bio-fermentation process and purified
through a 12-step micro-filtration system.
Because of its purity, Legend can be administered intravenously or intra-articularly—the only FDA-approved joint therapy product
labeled for both routes.
Intravenous administration alleviates the need for repeated intra-articular injections in horses and the associated complications
of joint infection, trauma, and reaction. It also ensures a rapid onset of action in multiple joints.
Is Legend effective? In field studies, clinical improvement was judged to be excellent or good in 90 percent of horses with
lameness that were treated with intravenous Legend.1
In addition, clinical improvement was judged to be excellent or good in 96 percent of horses treated with intra-articular
Additional studies have corroborated these results as well.Researchers at Colorado State University evaluated the use of intravenous
hyaluronate (Legend) on carpal joints in exercising horses after arthroscopic surgery and osteochondral fragmentation.3 In this study, 12 clinically normal horses underwent osteochondral fragmentation of the distal aspect of one radiocarpal
bone to simulate naturally occurring osteochondral fragmentation. Six of the horses were treated with 40 mg hyaluronate intravenously
and the other six with saline solution (placebo) intravenously once a week for three consecutive weeks on days 13, 20, and
27 after surgery. The horses were exercised on a treadmill five days a week beginning at 15 days and ending 72 days after
surgery. Lameness examinations were performed on the horses on day 72 after surgery; they were graded on a scale of 0 to 5
for severity according to American Association of Equine Practitioners (AAEP) guidelines. Synovial fluid samples were evaluated
from each middle carpal joint, measuring total protein, inflammatory cell, hyaluronate, glycosaminoglycan, and prostaglandin
E2 concentrations. Synovial membrane and articular cartilage were evaluated histologically.
How did the horses respond? In the forelimbs with osteochondral fragments, horses treated with hyaluronate intravenously had
lower lameness scores (Figure 1), significantly better synovial membrane histologic scores (significantly less inflammatory cell infiltration and less vascularity),
and significantly lower concentrations of total protein and prostaglandin E2 within synovial fluid 72 days after surgery than placebo-treated horses. Researchers concluded that intravenous hyaluronate
alleviates lameness by interacting with synoviocytes and decreasing inflammatory mediator production and release. They believe
that the results of their study indicate a prolonged beneficial effect after intravenous treatment with hyaluronate.
Tracy Turner, DVM, DACVS, of Anoka Equine Veterinary Services in Elk River, Minn., says that Legend® (hyaluronate sodium)
Injectable Solution gives veterinarians the opportunity to attack equine joint disease prior to cartilage breakdown, thus
increasing the viability of the animal.