Development and preliminary validity and reliability of the montreal instrument for cat arthritis testing, for use by caretaker/owner, MI-CAT(C), via a randomised clinical trial

•A pain scale (MI-CAT(C)) was developed for owners of osteoarthritic cats.•It was used with locomotor activity monitoring to assess meloxicam-treated OA cats.•Total scale intra-rater reliability, based on the primary owner, was excellent.•Scores fell with meloxicam and with higher locomotor activity, and rose with age.•Preliminary findings support the MI-CAT(C)’s reliability and validity in OA cats. Challenges in the clinical assessment of feline osteoarthritis (OA)-related pain and disability impede diagnosis and treatment of the disease. A pain scale was developed for use by cat owners and caretakers, the Montreal Instrument for Cat Arthritis Testing – Caretaker/Owner (MI-CAT(C)). Following content validation and a pilot assessment (n=11 cats with and without OA) of MI-CAT(C)-v1 reliability and validity, a randomised, double-blinded, placebo-controlled, crossover clinical trial was conducted; meloxicam efficacy in 54 OA-affected cats was evaluated using the MI-CAT(C)-v2 and locomotor activity monitoring (AM). The intra-class correlation coefficient was 0.81 for total scale intra-rater reliability, and 0.64 for inter-rater reliability; secondary owners tended to have more trouble completing the scale than did primary owners. Internal consistency assessed by Cronbach’s alpha was >0.70 for the total scale, but