ORIGINAL ARTICLE - RESEARCH Current use of biologic therapies for musculoskeletal disease: A survey of board-certified equine specialists Lindsay E. Knott DVM 1 | B. Alexander Fonseca-Martinez DVM, MSc 1 | Annette M. O'Connor BVSc, MVSc, DVSc, FANZCVSc 1 | Laurie R. Goodrich DVM, PhD, DACVS 2 | C. Wayne McIlwraith BVSc, PhD, DSc, FRCVS, DACVS, DACVSMR 2 | Aimee C. Colbath VMD, PhD, DACVS 1 1 Department of Large Animal Clinical Sciences, College of Veterinary Medicine, Michigan State University, East Lansing, Michigan, USA 2 Orthopaedic Research Center, C. Wayne McIlwraith Translational Medicine Institute, Colorado State University, Fort Collins, Colorado, USA Correspondence Aimee C. Colbath, MSU Veterinary Medical Center, 736 Wilson Rd, East Lansing, MI 48824, USA. Email: colbatha@msu.edu Abstract Objective: To evaluate the use of mesenchymal stem cells (MSCs), autologous conditioned serum (ACS), platelet-rich plasma (PRP), and autologous protein solution (APS) for the treatment of equine musculoskeletal disease by diplo- mates of the American College of Veterinary Surgery (ACVS), and American College of Veterinary Sports Medicine and Rehabilitation (ACVSMR). Study design: Cross-sectional study. Sample population: Diplomates (n = 423). Methods: An email link was sent to ACVS and ACVMR diplomates. A survey contained 59 questions regarding demographics, as well as indications, fre- quency, adverse effects, and limitations of use. Responses were analyzed using Fisher's exact test. Results: One hundred and fifty four surveys were analyzed. Years in practice and type of practice were not associated with biologic therapy use. PRP was the most used therapy (120/137; 87.5%). PRP and MSCs were most often adminis- tered intralesionally while ACS and APS were most often administered intra- articularly. ACS (50/104; 48.1%) treatment was repeated commonly within 2 weeks of initial injection. MSCs (39/90; 43.3%) and PRP (38/100; 38%) were commonly repeated 1-2 months after initial injection and APS was typically repeated >4 months after initial injection (21/53; 39.6%). Local inflammation and expense were the most common adverse effect and limitation of use. Abbreviations: MSCs, mesenchymal stem cells; ACS, autologous conditioned serum; PRP, platelet rich plasma; APS, autologous protein solution; ACVS, American College of Veterinary Surgery; ACVSMR, American College of Veterinary Sports Medicine and Rehabilitation. Some results of this study were presented at the AO Foundation Virtual Symposium - Bridging the Gap: Translating Clinical Research to Clinical Practice (December 7, 2020), and the North American Veterinary Regenerative Medicine Association Conference (September 22 - 24, 2021) in Fort Collins, Colorado. Received: 3 August 2021 Revised: 5 February 2022 Accepted: 20 February 2022 DOI: 10.1111/vsu.13805 This is an open access article under the terms of the Creative Commons Attribution-NonCommercial-NoDerivs License, which permits use and distribution in any medium, provided the original work is properly cited, the use is non-commercial and no modifications or adaptations are made. © 2022 The Authors. Veterinary Surgery published by Wiley Periodicals LLC on behalf of American College of Veterinary Surgeons. Veterinary Surgery. 2022;51:557–567. wileyonlinelibrary.com/journal/vsu 557