Intra-articular injections of polynucleotides show promise in improving clinical outcomes compared to hyaluronic acid in small-breed dogs with osteoarthritis

Objective To compare the therapeutic effects of IA polynucleotide (PN) and hyaluronic acid (HA) injections in small-breed dogs with osteoarthritis. Methods A multicenter, prospective, comparative, randomized, blinded clinical study was conducted from February 2024 to January 2025 at a university veterinary hospital and 3 veterinary clinics. Client-owned small-breed dogs (< 15 kg) with hindlimb osteoarthritis, confirmed by clinical signs and radiographic findings, were assigned to receive 2 IA injections of either HA or PN at a 1:2 ratio, with a 2-week interval. Clinical outcomes were evaluated at weeks 0, 2, 4, 8, and 12 using 2 validated clinical metrology instruments, the Canine Orthopedic Index (COI; function, gait, stiffness, and quality of life) and Canine Brief Pain Inventory (CBPI; pain severity score [PSS] and pain interference score [PIS]). Results Of the 34 enrolled dogs, 27 completed the study (HA, n = 9; PN, 18). The mean age was 6.3 years, with a median weight of 4.8 kg. The PN group showed significantly greater improvements in COI, stiffness, CBPI, and PIS compared with the HA group at week 12. The PN-treated dogs also experienced earlier or more sustained improvements in COI, stiffness, gait, CBPI, PSS, and PIS. The COI-defined success was observed from weeks 4 to 12 in the PN group and at week 8 in the HA group. Conclusions The IA PN injections resulted in earlier, greater, and more sustained clinical improvements than HA in dogs with osteoarthritis. Clinical Relevance Injections of PN may offer a more effective alternative to HA for managing canine osteoarthritis.