By Bob Menardi, DVM, and Eric Schreiber • Exubrion Therapeutics Cinder, a black labrador retriever, was always a fun-loving companion. Her pet parent, Terry, describes her as “my silly, happy, bouncy girl.” A canine athlete, Cinder participated in agility events until the age of 5 when she started noticeably restricting her movements. “Cinder is one of those dogs who doesn’t have a sense of self-preservation, so we knew something was really wrong when she showed a reluctance to jump,” Terry says. It wasn’t long until Cinder was diagnosed with osteoarthritis (OA), one of the most common and debilitating conditions in veterinary practice today.1 Over the next year, Cinder received numerous canine OA treatments, including NSAIDs, hyaluronic acid (HA), and platelet-rich plasma (PRP) injections, but none of these made much of a difference and the OA was progressing. “You could see how unhappy she was. She had a downtrodden look to her,” Terry recalls. “She didn’t want to come out of a dark bedroom, not even to eat, and I thought we were getting closer to having tough conversations about what do next. Do we take the unthinkable step of having to euthanize her? It was something we couldn’t even imagine ever having to do.” That’s when her veterinarian handed Terry a flyer for Synovetin OA®, a treatment that changed everything for Cinder. In the first three days following treatment, she was walking again. Three to four weeks later, she was running around with the family’s other labs and initiating play. The turnaround for Cinder is typical of the difference Synovetin OA has made for thousands of dogs. It’s completely different from other approaches to OA management that just treat symptoms. Instead, it’s the only treatment specifically designed to target the underlying cause of the disease—inflammation—and the resulting pain and progression of OA. A Disease of Inflammation Cinder’s story is not uncommon. In fact, roughly 25% of all adult dogs in the US suffer from arthritis joint pain, or about 1 in 4.1 Veterinarians are all too familiar with the signs: stiffness, lameness, difficulty rising, reluctance to jump or play. OA remains one of the most common causes of chronic pain in dogs—and also one of the most frustrating, because traditional treatments are typically designed to just treat pain signals rather than the underlying cause.2 Historically, OA has been thought of as a "wear-and-tear" disease of older dogs involving the mechanical breakdown of the joint over time. But now researchers and experts have proven it to be a disease of relentless inflammation that is directly responsible for the pain and progression of joint degradation, one which can affect even otherwise healthy young dogs. In fact, one study showed that radiographic evidence of OA was highly prevalent in dogs less than 4 years old, 60% of which were clinically affected.3 Whether triggered by developmental joint disease (i.e., elbow dysplasia), injury, or general cartilage degeneration, OA is driven by synovial inflammation (synovitis). This inflammation leads to significant pain and the production of pro-inflammatory mediators which break down cartilage, damage synovial tissue, and contribute to the sclerosis of subchondral bone. If left unchecked, this process becomes a vicious cycle. The inflammatory environment worsens, leading to more pain, more tissue damage, and ultimately, joint failure. Cartilage thins. Osteophytes form. The joint capsule thickens. And all the while, the dog’s pain and immobility increases. Without stopping the inflammation, we cannot truly control the pain and stop this vicious cycle. (Figure 1) OA progression is driven by a vicious cycle of ongoing inflammation, pain, and cartilage destruction. Figure 1. The Traditional Toolkit Has Its Limits The traditional approach to canine OA has largely focused on treatments such as NSAIDs, joint supplements, stem cell, PRP, and anti-nerve growth factor (anti-NGF) injections. These modalities offer important benefits, but they aren’t designed to treat the underlying cause of the disease. At best, they may buy time and potentially improve quality of life. At worst, they provide insufficient relief or carry risks that limit long-term use. Recent published data suggest the possibility that anti-NGF injections actually accelerate OA disease.2,4 This raises a critical question: What if we could do more than manage symptoms? What if we could target the inflammation driving the disease? A Different Approach Synovetin OA, a colloid containing microparticles of the radioisotope tin-117m, is an intra-articular veterinary device now available at over 100 practices across the US. It represents a paradigm shift: from managing symptoms by masking pain to breaking the vicious cycle of inflammation and helping to reduce pain at the source, while also preserving the health of the joint. Synovetin OA is injected directly into the affected joint. It is not a drug and is non-systemic. Once there, it delivers targeted radiotherapy to activated macrophages in the synovium and synovial fluid—the very cells that perpetuate inflammation in OA. Following treatment, inflamed, painful synovial cells (synoviocytes) take up the microparticles. The emitted energy (from conversion electrons) eliminates these cells, restoring the synovium and providing immediate pain relief. Macrophages in the synovial fluid also engulf the tin microparticles and are subsequently eliminated. This ends the production of cartilage damaging cytokines, thus breaking the destructive cycle at its source.5 Tin-117m conversion electrons are low energy, with a short tissue penetration range which is ideal for treating synovitis while remaining completely safe to cartilage, bone, or other joint structures.6 This approach offers advantages to veterinarians and pet parents alike:6-9 One simple, minimally-invasive outpatient treatment provides up to one full year of relief Targets the inflammation that causes pain and drives disease progression rather than just treating the symptoms Exceptionally safe with no systemic side effects for treated dogs No pet parent compliance issues that come with daily medications or monthly veterinary visits Pain Relief Plus the Potential to Slow OA Progression While long-term data in dogs is still emerging, preclinical studies in rodent models have shown evidence that tin-117m has the potential to slow disease progression, with substantial reductions in synovitis, cartilage erosion, and significant slowing of bony remodeling (as shown in osteophyte growth) observed. This raises the question: “Is Synovetin OA a disease-modifying osteoarthritis device?” It may be too early to tell, but these preliminary findings are promising—and exciting.10,11 New Hope for Dogs Suffering from OA and Pain For veterinarians and pet parents like Terry, Synovetin OA offers new hope and an “inflammation-forward” approach. With this novel modality, we can treat OA not as a degenerative process, but as an inflammation-mediated cascade that can be interrupted at all stages of the disease. This could be especially beneficial in early OA where the targeted action provides the best opportunity to relieve pain and break the vicious cycle to potentially slow progression.5-11 In Cinder’s case, this approach made all the difference. For the millions of dogs facing similar struggles, innovations like Synovetin OA may open the door to better outcomes for patients and their families, at all stages of the disease. “Cinder has now been treated three times with Synovetin OA, each time giving her more than one year of relief,” says Terry. “I have a happy, healthy, active, and pain-free dog again.” References ACVS. Osteoarthritis in dogs. Available at: https://www.acvs.org/small-animal/osteoarthritis-in-dogs/. Accessed April 7, 2025. Orthopedic Foundation for Animals. Available at: https://ofa.org/wp-content/uploads/2021/05/elbowarticle.pdf. Accessed April 7, 2025. Enomoto M, de Castro N, Hash J, et al. Sci Rep. 2024;14(1):2827. Farrell M, Waibel FWA, Carrera I, et al. Front Vet Sci. 2025;12:1581490. Stevenson NR, Lattimer J, Selting K, et al. Abstract S6-03. World J Nucl Med. 2015;14(Suppl 1):S15-S68. Lattimer JC, Selting KA, Lunceford JM, et al. Vet Radiol Ultrasound. 2019;60(5):567-574. Aulakh KS, Lopez MJ, Hudson C, et al. Vet Med (Auckl). 2021;12:117-128. Donecker J, Fabiani M, Gaschen L, Aulakh KS. PLoS One. 2021;16(7):e0254613. Donecker J, Lattimer JC, Gaschen L, Aulakh KS. Vet Med (Auckl). 2021;12:325-335. Doerr C, Stevenson N, Gonzales G, et al. J Nucl Med. 2015;suppl 3:1243. Doerr C, Bendele A, Simon J, et al. Poster presented at the Society of Nuclear Medicine & Molecular Imaging Annual Conference. San Diego, CA. 2016. Learn More To find out how Synovetin OA can fit into your OA treatment strategy, visit Synovetin.com or contact Eric Schreiber, Chief Commercial Officer, at eschreiber@exubrion.com. Important information about Synovetin OA. Studied in canine elbows, Synovetin OA is given by authorized veterinarians. Temporary discomfort in treated joints may occur. Visit Synovetin.com.
