Effects of hylan on amphotericin-induced carpal lameness in equids.

In this double-blind study, the effectiveness of and dose response to intra-articular administration of modified hyaluronan (hylan) was determined in an equine carpal lameness model over a 23-day period, using a computerized three-dimensional motion analysis system, synovial fluid variables, and synovial histologic examination. In 24 clinically sound horses, baseline motion data was acquired from horses trotting at 4 m/s on a high-speed treadmill. Then, to induce lameness, 25 mg of amphotericin B in 5 ml of sterile water was injected into the left middle carpal joint of each horse every other day for 3 treatments. Phenybutazone (2.2 mg/kg of body weight, PO, once) and butorphanol tartrate (0.1 mg/kg, IM, q 6 h, for 36 hours) were used to control signs of discomfort. Horses were assigned at random to 4 equal groups and received intracarpal administration of either 1, 2, 4 ml of hylan (8 mg/ml), or 2 ml of balanced electrolyte solution (control). Intracarpal administration of amphotericin B caused significant (P < or = 0.01) increase in subjective lameness grades over the 2-week evaluation period, and hylan administration did not significantly (P < or = 0.01) change the subjective lameness grade. Lameness induction caused significant (P < or = 0.01) decrease in head and withers excursions during the lame forelimb support phase and significant (P < or = 0.05) increase in head and withers excursions during the sound forelimb support phase.(ABSTRACT TRUNCATED AT 250 WORDS)