Robenacoxib for Feline DJD Pain — Adrian et al. 2021 Pilot RCT: Disability Reduction and Endpoint Methodology

Bottom line

• In a randomized blinded pilot clinical trial (Adrian et al., Sci Rep 2021) in 109 client-owned cats with chronic degenerative joint disease-associated pain, robenacoxib treatment compared with placebo produced a 49% reduction in owner-assessed disability (p = 0.01, effect size ~0.3) and a significantly greater success rate at 6 weeks (p = 0.018, NNT 3.8).¹
• Objective actimetry showed high within- and between-cat variability (82.4% of values were zero), but robenacoxib-treated cats showed a significantly higher proportion with >10% activity increase at 3 weeks (p = 0.046) and 6 weeks (p = 0.026).¹
• Adverse event frequencies did not differ significantly across treatment groups (PP, RR, RP).¹
• The study was designed as a pilot to identify suitable outcome endpoints for a confirmatory pivotal trial; findings support the use of owner-assessed outcome measures, particularly disability scales, as primary endpoints in future feline DJD trials.
• This is a clinician-facing evidence summary. It is not a dosing protocol; confirm regimen, monitoring and contraindications against current product labeling and a veterinary formulary.

Study design

Adrian et al. (2021, Scientific Reports, PMID 33833276) enrolled 109 client-owned cats with chronic DJD-associated pain in a parallel-group, randomized, blinded clinical trial with three treatment arms: placebo-placebo (PP), robenacoxib-robenacoxib (RR), and robenacoxib-placebo (RP), each period lasting 3 weeks. Outcome measures included actimetry (continuous accelerometry data) and owner-completed assessments covering disability, temperament, and overall happiness. Data were analyzed with mixed-effects and generalized mixed-effects linear models.

Evidence summary

Actimetry findings

Actimetry in cats is technically challenging: 82.4% of all activity values were zero, reflecting the predominantly sedentary nature of cats and the burst-activity pattern that makes continuous accelerometry difficult to interpret.¹ Despite this, a categorical analysis showed that more robenacoxib-treated cats had a >10% increase in activity at 3 weeks (p = 0.046) and 6 weeks (p = 0.026).¹ Mean total activity was numerically 5.7% higher in robenacoxib-treated cats but did not reach significance in the continuous analysis (p = 0.24), illustrating the statistical power problem with actimetry as a primary endpoint in feline chronic pain studies.

Owner-assessed outcomes

Owner-assessed disability showed a 49% reduction in robenacoxib-treated cats versus placebo after 6 weeks of treatment (p = 0.01, effect size ~0.3).¹ Owner-reported temperament improved significantly (p = 0.0039) and happiness improved significantly (p = 0.021) in the robenacoxib group at 6 weeks.¹ Categorical success rates at 6 weeks significantly favored robenacoxib (p = 0.018, NNT 3.8).¹

Safety

No significant differences in adverse event frequencies were detected across the PP, RR, and RP groups. This is consistent with the broader robenacoxib feline safety literature.

Endpoint methodology implications

This pilot trial's methodological contribution is its systematic comparison of outcome measures in feline DJD. The low actimetry sensitivity in cats means that owner-reported outcomes — disability scales, global assessments, and composite scores — are the more statistically sensitive and practically deployable primary endpoints for confirmatory trials.² This has informed subsequent feline pain trial design, including the 2024 ISFM/AAFP guideline framework's emphasis on functional outcome monitoring in chronic pain management.

A specific patient with feline DJD?

Get an instant cited answer — no signup needed for your first question.

Try Voyage Clinical Desk

References

1. Adrian D, King JN, Parrish RS, et al. 2021. Robenacoxib shows efficacy for the treatment of chronic degenerative joint disease-associated pain in cats: a randomized and blinded pilot clinical trial. Sci Rep 11(1):7721. https://europepmc.org/articles/PMC8032665
2. Gruen ME, Dorman DC, Lascelles BDX. 2017. Caregiver placebo effect in analgesic clinical trials for cats with naturally occurring degenerative joint disease-associated pain. Vet Rec 180(19):473. https://europepmc.org/articles/PMC5498173

Changelog

• 2026-06-23: First published.

---

For licensed veterinary professionals. Evidence summary, not clinical advice. Voyage is decision support, not a substitute for clinical judgment — always confirm dosing and treatment with current formularies and your own clinical judgment.