Use of bathroom scales in measuring asymmetry of hindlimb static weight bearing in dogs with osteoarthritis.

OBJECTIVE: The study assessed the use and reliability of bathroom scales as an objective measurement tool, and setting a normal variance of static weight bearing between hindlimbs.
METHODS: Two groups of dogs were tested: a healthy control group (n = 21) and a group (n = 43) of dogs with confirmed osteoarthritis in at least one stifle joint, with or without hip joint osteoarthritis. Static weight bearing was evaluated manually and measured with two bathroom scales. An orthopaedic examination was done and dynamic weight bearing was measured using a force platform. Radiographs were taken to confirm the presence of osteoarthritis, and dogs were divided into groups of severe and non-severe osteo- arthritic changes. Reliability by repeatability was tested using analysis of variance, and the congruity between static weight bearing and other evaluation methods with Kappa statistics and proportion of agreement.
RESULTS: The difference between the hindlimbs proportional to the body weight in control dogs was 3.3% (± 2.7%). The repeatability of measuring static weight bearing in the hindlimbs of osteoarthritic dogs with bathroom scales was 81% with osteoarthritic limbs, and 70% for unaffected limbs. The sensitivity of static weight bearing measurements using bathroom scales was 39% and specificity 85%. CLINICAL SIGNIFICANCE: Bathroom scales are a reliable, simple, and cost-effective objective method for measuring static weight bearing and can be used as an outcome measure when rehabilitating dogs with osteoarthritic changes in the hindlimbs.