My first blog on Librela got a lot of traffic and triggered a lot of questions. It was very new to the market when that blog came out and many owners were seeking information. Why? Two reasons:

1. When their dog received the medication, they had not been given a lot of information about it including risks and how it works.

2. Owners were seeing adverse events and were often being told it was not Librela that caused the change but something that might have happened anyways.

Since that blog was published in late 2023, more information about Librela has come to light. This has lead to a proliferation of news reports from many prominent publications, Facebook groups dedicated to the topic and many owner experiences shared on-line.

This blog will attempt to cover the key highlights of what has occurred from late 2023 to the most recent study by Dr. Mike Farrell et al. in May of this year.

April 2024 - Wall Street Journal Publishes Librela Article :

"What Killed Their Pets? Owners Blame Meds, but Vets Aren’t Sure"

Maker Zoetis says side effects are rare and its arthritis drugs are safe

December 16 2024 - FDA Releases “Dr. Veterinarian” Letter

The FDA approved Zoetis for use in May 2023 based on the research on safety and efficacy that was available to date. After its release, and due to the reporting of many adverse events (what most would call side-effects), the FDA then further investigated Librela.

Adverse effects reported by the FDA after administration of Librela included:

• Trouble walking (wobbly legs, especially in the back end)

• Changes in coordination or balance

• Seizures

• Changes in peeing or drinking habits

• Digestive upset

• And in rare cases, dogs became very sick or were euthanized due to complications

These reactions were not common, but they were serious enough that the FDA wanted veterinarians to be aware. Most of the reported side effects happened after the first dose, and in many cases, within the first few days. The FDA also called for vets to report an adverse events to the drug manufacturer Zoetis who would then report to the FDA. Alternatively, a vet could report directly to the FDA.

The full FDA report can be seen here.

December 18, 2024 - Zoetis Respond to the FDA Report

Zoetis responds to the “Dear Veterinarian” letter from the FDA calling it a “communication” and not a “warning” downplaying the concerns of many who read the report.

Zoetis went on to say that Librela had helped “millions of dogs with osteoarthritis” and that “no individual adverse event sign has been reported at a rate higher than rare, as defined by the European Medicines Agency (EMA) – representing less than 10 occurrences per 10,000 treated animals.”

February 4, 2025 - Zoetis updates Librela Product Insert

Zoetis updated it’s Librela label (aka the product insert) based on the post-approval experience. The press release on its website re-iterated its confidence in the safety and efficacy of the drug.

Changed from its previous version, the insert lists more side effects reported to the FDA, recommends that veterinarians discuss adverse effects with owners before administration of Librela and encourages vets to provide owners a copy of the drug’s information sheet. The side effects reported now include neurological ones - ataxia, seizures, paresis, proprioception deficits, paralysis.

The information sheet can be viewed here.

March 24, 2025 - Research: Librela vs. Meloxicam for Dog Arthritis Pain

Researchers compared Librela (bedinvetmab)nto meloxicam in dogs with confirmed arthritis. Over 8 weeks, they monitored pain and mobility using the Canine Orthopaedic Index (COI) which measures gait, stiffness, function and quality of life. 101 client-owned dogs with arthritis were recruited across multiple clinics in the UK.
One group received monthly Librela injections (52 dogs), the other took daily meloxicam (49 dogs)

Research findings:

• Both treatments worked equally well: COI scores dropped significantly in both groups. Librela showed a slightly bigger improvement—but the difference wasn’t statistically significant .

• Pain relief improved over time: The greatest benefit was seen by Week 6–8 in both groups

• Fewer side effects with Librela: Librela group had only 4 adverse events (skin, systemic and, musculoskeletal disorders), while meloxicam group had 17 adverse events (skin, digestive, systemic, musculoskeletal, behavioural and neurological disorders) mostly digestive issues (like diarrhea or vomiting)

• Kidney markers increased on meloxicam:

  • The meloxicam group showed a mild—but statistically significant—increase in creatinine, a sign of kidney strain.

• Librela offers similar pain relief to meloxicam, but with fewer digestive side effects and higher rates of compliance

• For pet owners who struggle with daily pills or whose dogs can’t tolerate NSAIDs, Librela is an excellent alternative.

• The authors concluded that both Metacam and Librela were effective pain relievers but Librela improves owner compliance and has less side effects

Important things to note from this study was that it only compared the two medications for 56 days which “limits the safety data conclusions.” This study included dogs of ages 1-16 with confirmed arthritis diagnosis on an x-ray and excluded any dogs with neurological symptoms. The study acknowledged the social media reports of neurological side effects on social media following Librela injections but that only dogs in the Metacam group had these adverse events. It also suggested that acute onset of neurological signs (such as ataxia and vestibular disease) are more common in older dogs and may be attributable to age alone and not any one medication provided in this study.

April 24, 2024 - Research on Global Trends on Librela Reporting

This paper analyzed global safety data on Librela from February 2021 to June 2024 and and reported side effects from the over 18 million doses given worldwide, tracking any reported side effects in that period

Study Findings

• Frequency of adverse events - About 9.5 events per 10,000 doses were reported—classifying them as rare

• Most common side effects (between 1–10 per 10,000 doses):

1. Lack of efficacy (dogs not improving)

2. Polydipsia (Increased drinking)

3. Ataxia (wobbling walking)

4. Increased or frequent urination

5. Poor appetite

6. Lethargy

7. Death (reported but still rare)

8. Vomiting
   

• Other side effects were very rare—under 1 per 10,000 treated dogs

• Adverse events were most commonly reported in older dogs (this accounted 80% of the dogs in the data) and dogs that were considered to be in “fair’ clinical condition

• Trends in reporting:

• The U.S., U.K., Germany, Spain, France, Italy, Canada, and Australia were the largest markets for Librela

• The highest reporting rates came from Canada, U.S., U.K., Australia, and Germany

• Reporting rates varied due to how long the product had been on the market in each country—for example, the U.K. had data for 41 months post-launch, while the U.S. had just 9 months

This paper also highlighted

May 9, 2025 - Research on Adverse Effects in Dogs Receiving Librea

The purpose of this study was to conduct a disproportionality analysis of musculoskeletal adverse events in dogs who received Librela vs dogs who received one of 6 other common medications used to treat osteoarthritis in dogs (Rimadyl, Metacam, Previcox, Onsior, Galliprant and Daxocox). In other words, were particular side effects reported more often for one drug than another. The authors expected that Librela would have no greater than 50% more adverse musculoskeletal events than the other drugs and that the reported events would “surge and taper” following the introduction of the drugs to the market.

Study Results:

• The expected results were not the actual results

• Ligament/Tendon injury, polyarthritis, fracture, musculoskeletal neoplasia (abnormal growth of tissue) and septic arthritis were reported approximately 9-time more frequently in dogs who received Librela

• 19 musculoskeletal adverse events were suspected to be linked to “accelerated joint destruction” or rapidly progressing osteoarthritis

• The total number of musculoskeletal adverse events for Librela over 45 months “exceeded those of the highest ranking NSAID (Rimadyl) by ~20-fold”

The study concluded that there are in fact more reports of musculoskeletal adverse events reported in dogs who received Librela than other meds that treat osteoarthritis in dogs. This supported the FDAs findings of “lameness” following Librela injections. The authors suggested further investigation of the drug and close monitoring of dogs who are receiving Librela.

Other important information to take from this paper:

• Rapidly progressing osteoarthritis (RPOA) was the reason that human trials into drugs similar to Librela were halted. There have been no prior reports of RPOA in dogs. However, veterinary clinicians were starting to observe suspected canine cases of RPOA in dogs receiving Librela. This was the impetus for this paper.

• Reporting errors were made by Zoetis in 52% (9/19) of cases that were reviewed for suspected RPOA including incorrect diagnoses, severity and outcome. Two cases were reported as “overdoses” who received a dose in the recommended range

• The study suggests that due to the role of nerve growth factor (the protein that is involved in sending pain messages to the brain and is reduced following Librela injections) in bone and cartilage repair that musculoskeletal adverse events should be an “expected consequence” of Librela

• The effects of cartilage damage, whether from Librela or naturally occurring osteoarthritis, is not reversible

• RPOA was not seen in pre-market studies because x-rays were not completed. However, it is not known if those x-rays would have shown changes in the joint or not

• RPOA is a term not currently used in the ‘veterinary dictionary’ and thus cannot be used at present to describe an adverse event that is reported

Librela - what's the bottom line? From the research that has occurred over the last 1.5 years we now know that there are more adverse effects from Librela than were previously known. We also know that some of these risks, while very rare, are very serious and life altering or life ending. If the question is "Does Librela work?" the answer is "Yes." The follow-up question, as stated by Dr. Mike Farrell, is "at what cost?" As an owner of a senior dog with osteoarthritis I know my own dog would be at risk of experiencing an adverse event/side effect. I personally, would be waying the risk and benefits of any medication for my dog's pain and arthritis to determine the best course of action. What the correct decision for my dog is, may not be the same for your dog. The vital ingredient? Knowledge. Knowledge about what the drug can offer but what it may take away. A highly informative and unbiased account of Librela is from the last study's primary investigator Dr. Mike Farrell and is entitled "Librela: Hero or Villain" which is available on Youtube.