A double-blinded positive control study comparing the relative efficacy of 2.5% polyacrylamide hydrogel (PAAG) against triamcinolone acetonide (TA) and sodium hyaluronate (HA) in the management of middle carpal joint lameness in racing Thoroughbreds

Abstract

The purpose of this prospective double-blinded positive control study was to compare the efficacy of 2.5% polyacrylamide hydrogel (2.5% PAAG) in the management of middle carpal joint lameness in Thoroughbreds against treatments of triamcinolone acetonide (TA) or sodium hyaluronate (HA). A total of 31 flat-racing Thoroughbreds with lameness (grade 1-3/5) localized to the carpus by intra-articular analgesia were selected. Following a radiological assessment of the carpi confirming the absence of fragment/fracture, the horses were randomly assigned for intra-articular treatment with either 2 ml of 2.5% PAAG, 12 mg TA or 20 mg HA (followed by two further intravenous treatments of 40 mg, at weekly intervals in the HA group only), by a treating veterinarian. All horses were rested for 48 hours post-treatment and then re-entered an unaltered training regimen. Subsequent examinations at 2, 4, and 6 weeks were performed by a blinded examining veterinarian for all groups, while horses treated with 2.5% PAAG were monitored for 12 weeks for recurrence of lameness. Significantly more joints treated with 2.5% PAAG were lame free (83%) at 6 weeks compared to TA (27%; P = .007) and to HA (40%; P = .04). There was no significant difference between TA and HA groups at any time. All the joints treated within 2.5% PAAG that were lame free at 6 weeks (10/12) were still lame-free at 12 weeks. In conclusion, treatment with 2.5% PAAG led to statistically superior results compared to TA and HA in the management of selected middle carpal joint lameness in flat-racing Thoroughbreds, with therapeutic effects persisting up to 12 weeks.

Highlights

• 31 lame racehorses enrolled in prospective double-blinded positive control study
• 2.5% PAAG tested versus TA/HA to abolish carpal lameness in flat-racing Thoroughbreds
• 83% of 2.5% PAAG treated joints lame free at 6w versus 27% for TA and 40% HA (P < .05)
• All 2.5% PAAG-treated joints lame free at 6w (10/12) remained lame-free at 12w
• Excellent tolerance of 2 ml 2.5% PAAG injected in 12/12 middle carpal joints

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