Article Type: A Commentary on: Musculoskeletal adverse events in dogs receiving bedinvetmab  (Librela) by Farrell M, et al. Front Vet Sci. (2025) 12:1581490. doi: 10.3389/fvets.2025.1581490  

Submitted: Frontiers in Veterinary Science: Anesthesiology & Animal Pain Management - October  16, 2025  

Authors: Mike Farrell, BVetMed, CertVA, CertSAS, DipECVS-SA, MRCVS1*, Matthew Warren  Brunke, DVM, DACVSMR (Canine), CCAT, Fellow, IAVRPT2,3, and Curtis Wells Dewey, DVM,  MS, CTCVMP, CCRP, DACVS, DACVIM (Neurology)3 

Affiliations: 1Vetlessons, Bury St Edmunds, UK; 2Veterinary Referral Associates, Gaithersburg,  MD, United States, 3Elemental Pet Vets PLLC, Freeville, NY, United States  

Scope Statement: This commentary addresses the prescient issue of blame culture and its serious  welfare implications for veterinarians. It details how a drug manufacturer has attempted to deflect  blame for high adverse event rates associated with one of its best-selling products by unjustifiably  questioning the clinical judgment of veterinarians. Authored by experts with no financial conflicts  of interest, this evidence-based commentary challenges misleading claims regarding bedinvetmab  (Beransa or Librela) and defends the core principle of open and honest reporting. 

Musculoskeletal Adverse Events in Dogs Receiving Bedinvetmab (Librela): A Response to  Misleading Claims  

Musculoskeletal adverse events in dogs receiving bedinvetmab (Librela) challenged the premise that  severe side-effects of nerve growth factor (NGF) suppression seen in humans would not translate to  companion animals (1). In principle, this research should have triggered a significant re-evaluation  of the drug’s benefit-risk profile by the manufacturer, prompting stringent patient selection criteria  and more robust, transparent pharmacovigilance. In practice, Zoetis vilified and trivialized the  research (2), forcing us to contextualize their false and misleading claims.  

A central tactic is the deflection of blame, exemplified by Zoetis labelling reports for dogs receiving  the recommended dose as ‘overdoses’ (1). While manufacturers are responsible for product safety,  clinicians must ensure therapy safety and communicate risk to caregivers. With escalating  depression and suicide rates (3), misplaced criticism of veterinarians must be taken seriously.  Deflecting blame onto veterinarians exposes them to baseless public criticism for ‘concealing’ risks  when, in reality, they are merely relaying the company’s own biased guidance. In effect, the  manufacturer is compromising the reputation of local veterinarians to protect its product.  

In December 2024, the U.S. Food and Drug Administration (FDA) issued a formal safety warning  for Librela (bedinvetmab) after identifying disproportionately high adverse event reports compared  with other OA drugs (4). Statistically significant safety signals included:  

• Neurological: focal seizures (41x higher risk), epileptic seizures (13x), encephalitis (8x),  neuromuscular disorders (8x), impaired consciousness (7x).  

• Musculoskeletal: osteosarcoma (5x), musculoskeletal disorders (4x), lameness (3x). 

• Others: collapse (4x), syncope (4x), polyuria (4x).  

Zoetis responded to the FDA’s “Dear Veterinarian” letter by claiming it was not a “warning” and  contained “no new public data” (5). Both claims are misleading. A formal alert from a regulator  detailing high rates of serious events is, by definition, a warning. Moreover, raw data becomes  meaningful new information only after expert analysis—the very service the FDA provided.  

Zoetis deflected blame onto veterinary professionals by suggesting the high adverse event rate was  fuelled by social media-driven “over-reporting” (4). This accusation questions the professional  judgment of our community, as 89% of reports were filed by healthcare professionals. This pattern  of questioning veterinarians’ clinical acumen continued in their response to the FDA’s safety signal  for ataxia—a distinctive uncoordinated gait. Despite the straightforward clinical distinction between  ataxia and weakness from osteoarthritis, Zoetis suggested veterinarians were misinterpreting the  two—a baseless claim that casts aspersions on our core clinical skills (6).  

While Zoetis was critical of veterinary professionals, the FDA was critical of Zoetis, having twice  cited the company for misbranding Librela with misleading promotional materials. The first  warning letter concerned the misrepresentation of clinical trial data on its professional website to  create a misleading impression of Librela’s efficacy (7). The second concerned promotional videos  that created a “misleading impression regarding the safety” of Librela because risks were not  presented with “a prominence and accessibility comparable to the benefits” (8).  

Zoetis, in turn, has consistently criticized independent researchers (Table 1), authoring two letters  dismissing safety concerns (13-14), and formally demanding the retraction of a critical evidence  analysis (15)1. Simultaneously, Zoetis’s own paid consultants are conducting internal drug safety 

investigations, creating an untenable paradox: the same entity working to downplay safety concerns  is positioned as the only qualified investigator.  

This strategy exploits a critical information gap. Reading all relevant published research is  impossible, so many veterinarians will be unaware that Zoetis’s criticisms are unfounded. Zoetis  capitalized on this by issuing their rebuttals in a promotional flyer (2)—a format exempt from  impartial, expert fact-checking. The biased information landscape is compounded by the fact that  6/9 specialists on a high-profile expert panel that recommended Librela as first-line therapy for mild  osteoarthritis declared financial ties to Zoetis (16).  

Regulators must make high-stakes decisions based on incomplete or conflicting data, a challenge  aggravated by intense media coverage and pressure from those with financial interests in the  outcome. Such conditions demand expert judgment in circumstances where randomized controlled  trials would be unethical or impractical, events are emergent, or immediate safety decisions are  required (12). Yet, history shows that necessary interventions are often deferred in the absence of  ‘solid’ evidence, with devastating consequences (17).  

The opioid crisis is a tragic example with stark parallels to the current situation. Like Librela,  OxyContin was a popular and effective painkiller, with over 14 million prescriptions dispensed in  only two years (18). But its blockbuster status was enabled by systemic failures in post-marketing  pharmacovigilance. Years passed before a causal link to addiction and overdose was established—a  delay that ultimately cost over 100,000 lives (19).  

The opioid crisis provides a worrying example of the ‘denominator fallacy’: using massive sales  figures to downplay risk. In 2012, enough opioid prescriptions were dispensed for every adult in the 

USA to have a bottle of pills (18), resulting in 16,007 deaths (19). Using sales figures as a  denominator results in a mortality rate of 0.006%, dramatically obscuring the true scale of the crisis.  

Zoetis persistently leverages the denominator fallacy with Librela—counting monthly doses sold  rather than individual patients treated—and its misleading effect is magnified by the extreme scale  of under-reporting in veterinary pharmacovigilance. For example, the clinical incidence of  gastrointestinal side effects for the NSAID carprofen is ~5%, yet a large-scale pharmacovigilance  study found a reported rate of only 0.013% (20). This 385-fold discrepancy between reality and  reported data illustrates the magnitude of the problem.  

This massive evidence-practice gap exposes Zoetis’s misleading safety claims. Applying a 385-fold  correction means events they classify as ‘rare’ become ‘common’ (6). The discrepancy is even  starker for efficacy: the post-marketing lack of efficacy rate is only 0.02% (6), while pre-marketing  trials found a ~40% non-response rate (21, 22). This 2,000-fold difference highlights the profound  unreliability of using uncorrected pharmacovigilance data to portray a drug’s risk-benefit profile.  

The veterinary profession has unique access to a powerful drug class deemed too risky for human  use. This privilege comes with a profound responsibility to respect emerging safety signals.  Ultimately, independent experts and caregivers are not responsible for proving a drug is safe or  unsafe. That responsibility lies with the manufacturer, who must prove that new safety signals are  not a cause for concern. Attacking the sources of safety signals with misleading promotional  materials is not a substitute for transparent evidence; it is an abdication of that core responsibility. 

Conflict of interest: The authors declare that the research was conducted in the absence of any  commercial or financial relationships that could be construed as a potential conflict of interest. 

Author Contributions: MF: Writing – original draft. MWB: Writing – review and editing. CWD:  Writing – review and editing. 

Funding: The authors declare that no financial support was received for the research and  publication of this article. 

Generative AI statement: The authors declare that no generative AI was used in the creation of  this manuscript.  

Acknowledgments: The authors are grateful to Mr Andy Farmer and his veterinary team at AllPets  Veterinary Centre for sharing their personal experience of reporting a severe adverse event to  Zoetis. 

References  

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Footnote  

1The retraction demand concerned a 2023 critical appraisal by Dr. Kronenberger (15). The existence  of this unpublished letter was confirmed by personal communication with the author (K.  Kronenberger, personal communication, 30 August 2025).