How effective is frunevetmab for feline osteoarthritis pain and how do I discuss it with clients?

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Frunevetmab (Solensia; Zoetis) is the only anti-nerve growth factor monoclonal antibody approved for feline osteoarthritis (OA) pain in the USA and is recommended as a first-tier medication for this indication. It is administered at a nominal dose of 1.0 mg/kg SC monthly (effective dose range 1.0–2.8 mg/kg SC), with injections given on days 0, 28, and 56 in the pivotal trial.12 Efficacy is meaningful but moderate in magnitude. In the pivotal controlled trial, frunevetmab produced significant improvement over placebo on owner-assessed client specific outcome measures at days 28 and 56, with a number needed to treat of 9 and a standardized effect size of 0.3 at day 56.1 Veterinarian-assessed joint pain scores improved significantly at days 56 and 84, with an effect size of 0.18 at day 56.1 A single monthly SC injection provides pain relief for at least 1 month in cats with OA.4 The effect size in the pivotal trial was smaller than the 0.74 seen in the earlier pilot proof-of-concept study, which the authors attribute in part to a larger caregiver placebo effect in the later, larger trial.1 The caregiver placebo effect is a critical factor when counseling clients. The placebo response in feline chronic pain trials is substantially higher than in canine trials, and the gap between placebo and treatment on owner-assessed measures was narrower in the pivotal trial than in earlier work.1 This means that some owners will report improvement regardless of treatment — frame this honestly: objective veterinarian-assessed joint pain scores confirmed a real drug effect, but owner perception alone is not a reliable sole endpoint.1 Frunevetmab is particularly relevant for cats with concurrent chronic kidney disease (CKD). OA and CKD co-occur in up to 70% of feline cases, and concern about renal toxicity drives reluctance to prescribe long-term non-steroidal anti-inflammatory drugs (NSAIDs) in older cats.3 Frunevetmab does not carry the renal safety concerns associated with NSAIDs an