The Canine Ledger

Librela and the Anti-NGF Antibodies: What the Adverse-Event Reports Show

A monthly arthritis injection for dogs has drawn safety warnings. What regulators and researchers found, who funded what, and what to ask your vet.

Written by thecanineledger

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In December 2024, the US Food and Drug Administration wrote to vets about reports in dogs treated with Librela, a monthly arthritis injection. The reports included “ataxia, seizures, other neurologic signs”, and increased thirst and urination. “In some cases, death (including euthanasia) was reported as an outcome of these adverse events” (FDA, Dear Veterinarian letter, 16 December 2024).

The FDA did not withdraw the drug. It had already “determined Librela to be safe and effective for its intended use”.

While Librela helps many dogs with arthritis pain, the safety questions around it are real and not yet settled. This page sets out what regulators and researchers have found, who paid for which studies, and what to ask your vet.

If your dog is on Librela and has trouble walking, a seizure, sudden lameness or swelling in a joint, contact your vet promptly. Severe signs need an emergency clinic.

Our note: The box above is our wording, built from the adverse events listed by the FDA and the EMA.

1. What Librela is

Librela (bedinvetmab) is a monoclonal antibody, a lab-made protein that blocks nerve growth factor (NGF). NGF helps drive arthritis pain. Librela is given as an injection under the skin once a month. It is made by Zoetis. Some papers also call it Beransa, a name used in some countries.

The European Medicines Agency’s veterinary committee recommended it for approval in September 2020 (EMA, Librela). The FDA approved it on 5 May 2023.

There is evidence it works. AAHA’s 2022 pain guidelines say “Studies have shown good pain relief with anti-NGF monoclonal antibodies in dogs” (AAHA, 2022 Pain Management Guidelines). A 2026 trial in 32 dogs found it worked at least as well as an established arthritis tablet over two months, measured by how the dogs put weight on their legs (Enomoto et al., Sci Rep 2026). That trial was funded by Zoetis.

2. The safety concern

The worry comes from human medicine. A 2026 review in the Journal of the American Veterinary Medical Association notes that “In humans, rodents, and rabbits, inhibition of NGF is associated with rapidly progressive osteoarthritis”. That is a fast breakdown of the joint, and it “ultimately prevented regulatory approval of human aNGFmAbs” (von Pfeil et al., JAVMA 2026).

The authors describe the suspected events in dogs as “purportedly rare”, but “irreversible and often catastrophic”. They call for “documented informed consent” before treatment.

3. What the reports show

SourceWhat it found
FDA letter, December 2024Reports of neurological signs, increased thirst and urination, and some deaths.
Farrell et al. 2025 (European adverse-event database, 2004–2024)Ligament and tendon injury, polyarthritis, fracture, musculoskeletal tumours and joint infection “were reported ~9-times more frequently in Librela-treated dogs than the combined total of dogs treated with the comparator drugs.” An 18-member expert panel reviewing 19 cases “unanimously concluded a strong suspicion of a causal association between bedinvetmab and accelerated joint destruction” (Farrell et al., Front Vet Sci 2025).
Budsberg et al. 2026 (Zoetis’s own safety database, November 2020 to December 2025)Of 319 possible cases, 186 had unusual X-ray changes, most often in the elbow or hock. “Concurrent administration of NSAIDs was reported in 118 dogs (63%)” (Budsberg et al., JAVMA 2026).
EMA label change, November 2025Diarrhoea and vomiting added as rare side effects; immune-mediated polyarthritis, paresis, paralysis and seizure as very rare. New warnings for dogs with existing immune-mediated conditions or seizure disorders (EMA committee highlights, 4–6 November 2025).

Reports aren’t rates. Adverse-event databases show what vets and owners chose to report. They can’t tell you how often a problem happens, or prove the drug caused it. A newer drug that is in the news may be reported more.

Our note: “Rare” and “very rare” have defined meanings in EU labelling, which we haven’t read.

4. The two sides, and who funded them

Zoetis-employed authors published a reply to the Farrell study. They wrote that “Zoetis does not exclude the possibility of any AE”, but that the study “lacks a true case-control design and scientific rigor in case selection and evaluation”. They also pointed to past anti-inflammatory use in many of the cases: “(14/19 cases)” (Simon et al., Front Vet Sci 2025).

On funding:

  • The Farrell study declares “the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.” Several of its authors also wrote the 2026 review in §2.
  • The Zoetis reply was written by Zoetis employees and funded by Zoetis.
  • The 2026 trial in §1 was funded by Zoetis, and two of its authors have received consulting fees from Zoetis.
  • AAHA’s guidelines are supported by grants from companies including Zoetis.

A 2026 review of the published safety studies concluded: “There is conflicting evidence regarding the safety of bedinvetmab, though stronger evidence supported the safety of bedinvetmab when administered for under 3 months” (Yang and Macarthur, Aust Vet J 2026). Its authors, who declare no conflicts, judged that “the results generated by the three RCT studies are much more reliable than the DA”, meaning the randomised trials over the database analysis. Those trials were short, which is why the long-term question remains open.

Our note: We read the abstracts and key sections of the Farrell study, the manufacturer’s reply, the 2026 trial and the 2026 appraisal. We read only the abstracts of the Budsberg and von Pfeil papers.

5. What to ask your vet

Librela may still be the right choice for your dog. These questions can help you decide together:

  • What are the alternatives for my dog, and how do their risks compare?
  • Does my dog have a seizure disorder, an immune condition, or anything else that makes this riskier?
  • Should my dog have X-rays before starting, and again later?
  • Will my dog take any anti-inflammatory alongside it?
  • What signs should make me call you?
  • How will we judge whether it’s working, and when would we stop?

If your dog has a problem after an injection, ask your vet to report it. The FDA asks vets to report to Zoetis or directly to the FDA.

Our note: Approval dates, product names and labelling differ by country. We checked the EU and US only.

6. What we could not verify

Commonly saidWhat we found
“Librela is dangerous”Not established. Serious events are reported; how often they happen is not known.
“Librela is completely safe”Not established either. Regulators have added warnings since launch.
“Librela destroys joints”Suspected in some cases, by an expert panel; disputed by the maker.
“The FDA pulled Librela”False. We found no withdrawal on the FDA pages we read.

Sources

Always confirm with your vet before acting on anything on this page.