Intra-articular administration of a 2.5% polyacrylamide hydrogel (PAAG- Arthramid Vet) is shown to reduce or abolish lameness in distal interphalangeal (coffin) and metacarpo/ metatarso- phalangeal (fetlock) joints in horses undertaking equestrian disciplines. To date there had been no studies evaluating its’ efficacy in inter-carpal (knee) joints of racehorses conducted in a blinded fashion or up against standard treatments (controls).
To investigate the efficacy of a 2.5% PAAG (Arthramid Vet) in the management of inter-carpal joint lameness in racing Thoroughbreds.
Prospective double-blinded positive-control study.
33 flat-racing Thoroughbreds in full training at a single training facility with lameness (AAEP 1-3/5) localised to the inter-carpal joint by intra-articular analgesia and radiological assessment were enrolled. Horses were randomly allocated to be treated intra-articularly with either 2ml of a 2.5% polyacrylamide hydrogel, 12mg of triamcinolone acetonide (cortisone) or 20mg of sodium hyaluron (Hyonate®- followed by 2 further intravenous treatments of 40mg, at weekly intervals), by the treating veterinarian. All horses were rested for 48 hours’ post-treatment and then re-entered an unaltered training regime. i.e. kept in full work.
Subsequent examinations at 2, 4, and 6 weeks were performed by the blinded examining veterinarian for all groups. Horses treated with the 2.5% PAAG (Arthramid Vet) were monitored through to 12 weeks for reoccurrence of lameness in the treated joint.
Compared to horses that received triamcinolone acetonide or sodium hyaluron, horses treated with 2.5% PAAG (Arthramid Vet) showed a greater chance of resolution of lameness, joint effusion and reaction to passive flexion at four (p<0.05) and six (p<0.05) weeks, with no difference seen between groups at 2 weeks. There was no significant difference between the triamcinolone acetonide and sodium hyaluronate groups at any time point. Two-thirds (67%) of horses treated with the 2.5% PAAG hydrogel were still lame-free at 12 weeks.
This study indicates that a 2.5% PAAG (Arthramid Vet) hydrogel can be used in the management of inter-carpal joint lameness in flat-racing Thoroughbreds and was superior to and longer lasting than both Triamcinalone and Hyaluronic Acid. A reduction in joint effusion and reaction to passive flexion aligns with the proposed mode of action of Arthramid Vet.
Table 1: Pre-admission variables per treatment group. There was no statistically significant different between treatment groups.
|Age: range (mean)||2-5 (3.08)||2-4 (3)||2-6 (2.8)|
|Sprinter (%)||5 (42)||5 (45)||4 (40)|
|Miler (%)||5 (42)||4 (36)||4 (40)|
|Stayer (%)||2 (16)||2 (19)||2 (20)|
|Lameness range (mean)||1-3 (1.67)||1-4 (2.18)||1-3 (1.8)|
|Effusion range (mean)||0-2 (0.5)||0-1 (0.1)||0-2 (0.2)|
|Reaction to flexion range (mean)||0-2 (0.67)||0-2 (0.54)||0-2(0.6)|
|Radiological score range (mean)||0-2 (0.5)||0-2 (0.63)||0-2 (0.6)|