Q&A: What Zoetis' new JAVMA study reveals about Librela and a rare condition in dogs

A new study published in the Journal of the American Veterinary Medical Association (JAVMA) describes a rare, newly named condition—abnormal periarticular bone remodeling (APBR)—identified in a small number of dogs treated with Librela (bedinvetmab), Zoetis's monoclonal antibody therapy for canine osteoarthritis (OA) pain. The study, led by Steven C. Budsberg, DVM, MS, DACVS, and colleagues, drew on Zoetis's pharmacovigilance database and identified 186 affected dogs out of an estimated 34 million doses dispensed.

Richard Goldstein, DVM, DACVIM (SAIM), DECVIM-CA, global chief medical officer at Zoetis, spoke with dvm360 about how the research came together, what APBR is, and what veterinarians should discuss with pet owners when weighing OA treatment options.

RELATED: Rethinking pain: Q&A with Richard Goldstein, DVM, DACVIM (SAIM), DECVIM-CA, on preventive OA management

Editor's note: Below is the transcript from a verbal interview, which has been edited for a written format.

dvm360: Can you tell us a bit about your background and your current role at Zoetis?

Goldstein: I'm Richard Goldstein, a veterinarian and internal medicine specialist. In my past, I've been in academia at Cornell University, [and] I've been the chief medical officer of the Animal Medical Center of New York. My current and most significant role, is global chief medical officer for Zoetis where I am heavily involved in the medical parts at Zoetis, and representing Zoetis to the medical community.

dvm360: There has been recent research published in JAVMA surrounding Librela. Can you give us some insight into that?

Goldstein: The publication that came out today, authored by Budsberg, et al., is a result of us being aware that there were cases being discussed on listservs and in publications, and that Zoetis saw in our own pharmacovigilance data, which we monitor very closely, that there appeared to be something abnormal happening in a very small number of dogs with their joints [while] they were on Librela. Obviously, in the pharmacovigilance database, all you see is the dogs that are on Librela — you don't see other dogs. As we always do, we wanted to understand exactly what's happening, [and] whether or not it's associated with Librela.

This publication is a result of Zoetis opening our pharmacovigilance database to a group of experts: surgeons, radiologists, pathologists, experts in human orthopedic disease. We asked them, independently, to look at these cases, figure out who should be included in this group for this study based on search criteria of our database, and then try to characterize what is being seen in the most objective way possible. Zoetis has been very hands-off, this is really their publication and their opinion of what is being seen, but it is our pharmacovigilance database, and I think it's important that we be 100% transparent. Even if things are happening uncommonly, or there aren't many of them, every dog is important, and so we want to make sure that all this data gets out as quickly as possible to the community, so veterinarians can make decisions regarding Librela and be aware of what's happening.

It describes what the radiographic appearance is in these dogs that are in the paper, and it also talks about the number of dogs. They ended up finding 186 dogs with this identified condition, out of our entire database, using search criteria, including the fact that we could have radiographs — I'm sure there's going to be more that we couldn't get radiographs from, but it's likely a very small number. There were 34 million doses of Librela dispensed during the time that this study was done.

dvm360: What did the study conclude, and what did the research team find?

Goldstein: The study identified this syndrome, Abnormal Periarticular Bone Remodeling (APBR) and this study is the first finding that this exists. Abnormal periarticular means around the joint — it's not really the joint surface itself. This is new bone formation around the joint, and that's what's unusual about it.

We don't know exactly what the influence of Librela is on these dogs, and why this is showing up in this small population of dogs. But it is an unusual radiographic appearance that has been described in a few publications recently by others who have seen these cases in other databases. They’re the same cases, because all the cases in the other reports were provided to the reviewers for screening, and each one with a radiograph was reviewed by the authors. Since it is being discussed a lot, we wanted to make sure we get the facts out there, with complete transparency [from] our entire pharmacovigilance database, so people would know both what it looks like and what the context is in terms of the numbers.

With this being the first major Librela study that goes beyond case reports, this is the first insight into a phenomenon that has happened [and] is happening. The context is important: we're talking about less than 200 dogs identified in this study. Now, again, there may be [somewhat] more, out of the millions of dogs that have received Librela. But radiographic appearance is important — veterinarians [can] start understanding it, learn to recognize it.

It's very hard, just looking at a pharmacovigilance database that has no controls — we don't know what's happening with all the dogs on Librela that don't have this, or don't have any adverse events, which is millions and millions of dogs. The next step is going to be to try to figure out why this is happening in this very small group of dogs. Is there an influence of Librela or not, and if so, what is it? What can we do in terms of guidance? If there are risk factors we can identify, should we avoid it in certain cases, or how do we even monitor it early? The cases in the database are relatively advanced, so what does it look like in earlier stages? Can we catch it early? And what's the best thing to do, from a clinical perspective, if a veterinarian feels like this is developing? Those are questions that are still unanswered, but this is the beginning of this journey, and we will continue to work on it diligently until we get all those answers as best as we possibly can.

dvm360: What was the inspiration for bringing together specialists from so many different backgrounds, including human medicine experts, for this research?

Goldstein: When we first started, we didn't know what we didn't know. The key element here is the radiographs and the clinical story, so we needed radiologists and we needed surgeons who are experts in these areas. We added pathologists because we thought that in this process people might be submitting tissue — we didn’t get a lot of tissue at all, but we thought we might, and we thought that would be important. And the reason we had human experts is [that] there's just a lot of experience [built up] over the years looking at pharmacovigilance databases, looking at unusual findings, and we wanted to make sure that if there was something from the human side, we could understand better, that would help our patients.

dvm360: How should veterinarians factor this into conversations with pet owners about OA treatment options?

Goldstein: From a veterinarian's perspective, this is something that should be discussed with pet owners, just like every other adverse event. I feel very strongly that the conversation and the decision veterinarians make [with clients] is around risk versus benefit. When a dog is in pain from osteoarthritis, the option shouldn't be [whether] to treat or not to treat — we need to alleviate OA pain. That's why we all took an oath, that's why we all became veterinarians: to keep dogs from being in pain.

So the question a veterinarian has to ask is: This is a dog in pain, this dog has osteoarthritis, I need to alleviate this pain — what are my best options to do that? There's a whole approach to alleviating OA pain. It's not just medications; it's weight loss and exercise. But when it comes to actual medications to alleviate pain, veterinarians have a choice, and they have to weigh the risk-benefit of each option and choose the best recommendation for each individual pet. To do that, they have to have all the information they possibly can — they have to know what's happening with NSAIDs [nonsteroidal anti-inflammatory drugs], what's happening with Librela: what the risks are there versus the benefits for both. That's important for them to take into account, as well as the context — the small number of cases identified in our review —compared to the millions of dogs getting Librela .

The same risk vs. benefit conversation needs to happen with the pet owner: “I've diagnosed your dog with osteoarthritis. I feel like your dog is in pain. We don't want your dog to be in pain. Here are the choices, and this is my recommendation.” There is a client information sheet in the US for veterinarians to use, though the APBR information is not on there at this time so it will need to be discussed directly, but the specific symptoms/indicators are on the CIS.

For APBR, I would recommend: there is this condition that has been reported, and while we only identified a small number of cases in our review, it is out there and could happen, and we will monitor for it. When you have that discussion up front with pet owners, they're more informed, they trust you, and you make that decision together based on information available. Again, the next step will be [figuring out] if there's a way to minimize the risk for it, and then what to do when you find it — but that's something we're going to have to keep working on.

dvm360: How does this kind of transparency help veterinarians navigate misinformation clients might encounter, on social media, for example?

Goldstein: It's a big part of being a veterinarian today — it is a team sport. It's the pet owners, the veterinarian, and the entire veterinary health team, the technicians — everybody is in this together. And [pet owners] may also be hearing things on social media or other places, so it's important the veterinarian has all the facts. The veterinarian is the scientist in that group, the source of knowledge, the source of truth. So the more facts we can supply to the veterinarian, the better equipped they'll be to manage all the other stuff people hear around them that may or may not be as factual.

I feel it's important to acknowledge what people have learned on social media and address it — we can't just tell them we don't want to hear it. But at the end of the day, the relationship has to be that the veterinarian is the expert, and for that, the veterinarian has to have all the information. This is part of that process.

dvm360: Why is research and data transparency, like publishing your pharmacovigilance database, so important in veterinary medicine?

Goldstein: Zoetis took the step to publish a summary of the global pharmacovigilance data last year, in 2025, and we've done the same for some other products, and we'll continue to do so. Information is power. Data is power, and research and science [are] power. I believe really strongly [that] we are a company of science. We want to be transparent, we want to publish science based information. That's the way [we operate].

We also have a lot of studies [underway] with real-world evidence. So we'll say to, for instance, a corporation in the US, “You have a lot of data, you're treating thousands and thousands of dogs with our products — please publish it, and we'll help you publish it if you need resources.” But we want [them] to publish it on their own, without any bias from us, and publish no matter what, because it's important. [I] believe really strongly in our products, including Librela, and it's important that as much information as possible on its use in the real world comes out. So I think it's tremendously important, and I hope everyone follows suit.

dvm360: Was there anything that surprised the research team about the study's findings?

Goldstein: I think the initial appearance is new to people, or at least we feel like we haven't seen it often before. I think how few cases were ultimately identified as APBR in context to the social media aspect of it. I don't want to minimize any adverse event, or any single dog, or any group of dogs that has an adverse event from medication. But if you look at just what's out there in terms of social media, and then the actual number of cases they were able to identify in the study — and again, there may be some more — that, to me, is the biggest discrepancy. And it speaks to why it's so important to get the actual facts out, versus just relying on what people hear on social media.

dvm360: Why is diagnostic imaging important for confirming a suspected OA diagnosis?

Goldstein: It's really important to diagnose OA for many reasons. You want to be able to address the underlying cause — osteoarthritis in dogs is typically secondary to some abnormality, so maybe there's a specific treatment for that abnormality. And you want to diagnose OA to make sure you're following the correct treatment protocols specifically for OA versus neuropathic pain, a neurologic disease, or other causes of pain the dog might have.

dvm360: Based on the radiographs, do you have any sense yet of what's driving these changes in dogs following Librela treatment?

Goldstein: We don’t know yet, and again, we don't know that it doesn't happen in dogs without Librela as well. This study is not able to prove causality. There's likely an association here, in this small number of dogs It would be way too soon to theorize on a mechanism, but that's something we definitely need to try to figure out — what's special about these dogs? Clearly, [this process isn't happening in] the vast majority of dogs, so what is predisposing this group of dogs for this to happen, Librela or no Librela? And what is the potential influence of Librela on the process? That's really important, because that's the kind of information veterinarians are going to need to make clinical decisions.

It's really hard when something is so rarely reported, because you can't study it prospectively — we can't just [survey] 100 dogs and expect this to happen and figure it out along the way. So we have to use large databases, we have to control that data against dogs that did not get Librela, and we have to investigate, as much as we possibly can, every single dog that did get it in our database — what was unique to this dog versus all the other dogs? It's a lot of work, but we are definitely dedicated to [doing] it. No question.

dvm360: Is there anything else you'd like veterinarians to take away about this study and what comes next?

Goldstein: The conclusion is only the beginning of the story. This is the context, and now we need to get to work figuring out why, how, who, and all the other questions that need to be answered — but [this study gives us] the foundation to start that. It's putting the information out there so people have it, but obviously it can't answer all the questions. We need to do a lot more work.

Check out the full study here.