Scott McClure, DVM, PhD, Dipl. ACVS, ACVSMR, owner of Midwest Equine Surgery & Sports Medicine, in Boone, Iowa, and colleagues recently evaluated the polyacrylamide hydrogel product in two studies, and he presented their results at the 2018 American Association of Equine Practitioners Convention, held Dec. 1-5 in San Francisco, California.
Polyacrylamide hydrogel is a nondegradable synthetic viscous gel that has been shown to decrease knee OA symptoms in human patients. There’s less research in horses, so McClure and team set out to evaluate the 4% polyacrylamide hydrogel (available in the U.S. as Noltrex Vet, he said). In one study they evaluated the gel’s clinical, histologic (tissue structure), and metabolic effects in six healthy horses’ fetlock joints. They evaluated synovial fluid seven, 28, and 56 days following intra-articular (IA, in the joint) gel injection and analyzed cartilage and synovial membrane samples under a microscope.
McClure said the polyacrylamide was visible on the synovial membrane (joint capsule lining) seven days post-administration, and it was present between cells of the synovial membrane at Days 28 and 56. Further, they found no adverse effects following IA administration.
Then, they investigated the gel’s impact on 28 horses diagnosed with naturally occurring OA in a field trial. They administered IA polyacrylamide hydrogel and evaluated horses 45 and 90 days post-injection. McClure said they defined treatment success as lameness improvement by at least one grade or reduced pain scores, improved range of motion, and reduced joint swelling.
They found that:
- Average lameness scores decreased significantly, from 2.34 to 0.87;
- 23 horses (82%) showed improvement based on the study criteria at Day 45 post-injection;
- 21 horses (75%) still met the criteria for improvement at Day 90; and
- None of the 43 injections administered (eight horses had two injections) were accompanied by adverse effects.
The team concluded that the IA polyacrylamide hydrogel decreased lameness long-term in horses with naturally occurring OA.
“This is an exciting new therapy for managing horses with OA,” McClure said. “It adds another viable treatment to the veterinarian’s options. We will continue to learn more about this treatment and how to improve the horse’s soundness as we proceed.”