Measuring Chronic Pain in Osteoarthritic Dogs Treated Long-Term with Carprofen, through its Impact on Health-Related Quality of Life

Introduction: Health-related quality of life (HRQL) is key to measurement of osteoarthritis impact in people. VetMetrica is a web-based owner questionnaire which generates scores in 4 domains of HRQL–energetic/enthusiastic (E/E), happy/content (H/C), active/comfortable (A/C), calm/relaxed (C/R) in dogs. Continuous versus intermittent therapy with NSAIDs offers pain control, greater mobility and slower OA progression, but limited studies have shown these benefits. Carprofen treatment for up to 8 months in dogs with OA was investigated to demonstrate whether a sustained improvement in chronic pain as measured by its impact on HRQL would occur.

Materials and Methods: Owners of dogs with newly diagnosed OA were recruited and requested to complete assessments at baseline and 14, 28, 60, 128, 180, 240 days after beginning treatment with label dose carprofen. Group mean and 95% confidence intervals at all time points and significance between baseline and 14 days using paired t-test were calculated.

Results: Owners of 29 dogs (16 females, 13 males, mean age 8.9 ± 2.9) were recruited. Twenty-one completed assessments to 240, 25 to 180, 27 to 60 and 29 to 28 days. Significant improvement at 14 days relative to baseline (E/E, H/C and A/C, p ≤ 0.001 and C/R, p = 0.023) reaching maximum at 60 days for E/E and A/C and at 28 days for H/C and C/R was demonstrated. Thereafter improvement was generally maintained until treatment end.

Conclusion: Long-term carprofen improves HRQL in OA, providing evidence to support its continuous use for up to 8 months, when used as labelled in appropriately selected dogs.

Acknowledgements: This study was funded by Zoetis. Professor Reid is a director and Dr Noble an employee of NewMetrica Ltd, a company that provides VetMetrica under commercial license for clinical trials. Dr Wright and Dr Gober are employed by Zoetis.