A case series report following the treatment with 2.5% polyacrylamide hydrogel of 804 joints in 341 horses (average of 2.36 joints per horse). The treatments were carried out by three different vets, each at a different practice. The practices were chosen due to the diversity of their equine populations.

Reasons for performing the case series:

Intra-articular administration of a 2.5% polyacrylamide hydrogel (2.5% PAAG) has been widely used to treat non-septic arthritis since its introduction to the United Kingdom animal health market, 7 years ago. In order to support an application for Marketing Authorisation (MA), further information, particularly on the safety of the product has been sought from veterinary practices in the United Kingdom.


To retrospectively analyse data from horses treated with 2.5% PAAG from three specialist equine practices in the United Kingdom.

Study design:

Retrospective case series.


Horses showing clinical signs of non-septic arthritis were treated intra-articularly with 0.4ml-4mls (dose dependant on joint/s affected) of 2.5% PAAG, by a treating veterinarian. The tarsometatarsal (“TMT”) joint, distal intertarsal (“DIT”) joint, fetlock joint and distal interphalangeal (“DIP”) joint accounted for 89.7% of all joints treated. Ancillary treatments commonly included anti-inflammatory and/or hyaluronic acid preparations and less commonly digital neurectomy.


A total of 341 horses, comprising 804 joints were available for analysis. The veterinary practices involved were all specialist equine centres, whose patients were principally racing thoroughbreds.  70/80 (87.5%) and 232/261 (88.9%) of those treated with 2.5% PAAG and ancillary treatment, and those treated with 2.5% PAAG alone respectively, achieved the anticipated outcome within two months. 15.8% (15/341) received additional injections of 2.5% PAAG, after the initial treatment and 61.6% of horses (210/341) were still in full exercise at least two years after the initial 2.5% PAAG treatment.   Adverse reactions were extremely rare, occurring in only 0.59% of horses (2/341), and both of which responded to conservative therapy.


Case selection bias, lack of controls, no blinded assessment. Pending publication.


This case series shows that 2.5% PAAG is safe and effective at alleviating the clinical signs of non-septic arthritis. There appears to be no major benefit or deleterious effect derived from ancillary treatments. Efficacy results appear consistent with those from previously published studies.