Gait analysis has been used in patients with rheumatoid arthritis to study both static and dynamic lower limb functional disability or improvement after treatment [
1,
2]. It has also been used for the study of various models of arthritis [
3‐
6]. The CatWalk system, which is a video based automated gait analysis system was developed to evaluate footfall and gait changes in rodents [
7]. It can record both static and dynamic parameters such as paw pressure, print area, stance phase duration, swing phase duration, stride length as well as interlimb coordination. Recently, the CatWalk system has been used for studying rodent models of arthritis, mainly the rat model [
8‐
16]. Functional changes caused by arthritis and the effects of analgesic drugs have been analyzed in some of these models using the CatWalk system [
8‐
10,
12,
15]. The evaluation of the usability of this system in different mice models of arthritis is important taking into consideration that mice are extensively used in the study of the disease, both in the pathogenesis of the disease and search for therapeutic targets and molecules, and also that mice are the preferred animals for genetic modification to study biology and disease [
17]. The background mouse strain most commonly used for the production of transgenic mice is the C57BL/6 (
http://jaxmice.jax.org/strain/000664.html). Two previous studies described the use of the CatWalk system in assessment of weight bearing changes and effects of a non-steroidal anti-inflammatory drug in a lipopolysaccharide (LPS)-induced monoarthritic C57BL/6 mouse model [
8,
15]. However, the analysis was limited to static changes, print area and weight bearing, only. Beside the CatWalk system, other gait analysis systems have been used to evaluate gait in mice with arthritis. One study used DigiGait Imaging System (Mouse Specifics, Inc.), which is to some extent similar to the CatWalk system, to evaluate both static and dynamic parameters in mice with collagen-induced arthritis (CIA) [
6]. Locomotion has also been studied in mice with CIA using a computerized tracking system and image analyzer (EnthoVision 3.1, Noldus) and was found to be correlated to clinical arthritis [
18].