Use of an activity monitor to detect response to treatment in dogs with osteoarthritis.
OBJECTIVE
To determine whether an activity monitor (AM) could be used to detect changes in activity in dogs with osteoarthritis treated with carprofen or a placebo.


DESIGN
Randomized controlled trial.


ANIMALS
70 dogs with no clinically important abnormalities other than osteoarthritis for which they were not currently being treated.


PROCEDURES
Dogs wore an AM continuously for 21 days. On days 8 through 21, the dogs were treated with carprofen (n = 35) or a placebo (35). Total activity counts for days 1 through 7 (baseline) were compared with total activity counts for days 15 through 21 (endpoint). The change in total activity count from baseline to endpoint was assessed within each treatment group as well as between groups. Linear regression analysis was performed to test for an association between treatment and percentage change in activity counts while controlling for other variables.


RESULTS
For placebo-treated dogs, median baseline total activity count was not significantly different from median endpoint total activity count (1,378,408 vs 1,310,112, respectively). For dogs receiving carprofen, there was a significant increase in median activity count from baseline to endpoint (1,276,427 vs 1,374,133). When age and baseline activity counts were controlled for, dogs in the carpofen-treated group had a 20% increase in activity counts, compared with placebo-treated dogs (95% confidence interval, 10% to 26%).


CONCLUSIONS AND CLINICAL RELEVANCE
Results suggested that the AM used in the present study may be a valid outcome assessment tool for documenting improved activity associated with treatment in dogs with osteoarthritis.