BBB is a locomotor rating scale; you put 1 or 2 animals in an open field, then 2 observers observe the animals and score what they see by means of the BBB coding scheme.
BBB is intended to measure the functional recovery of an animal after experimental spinal cord injury (BBB is for rats and BMS is for mice). Part of the BBB score relates to interlimb coordination (which paw is placed after which paw). You can use CatWalk to measure the BBB score by using the Regularity Index. This CatWalk-based BBB score turns out to be more sensitive than the standard BBB score (Koopmans, G.C., Honig, W.M.M., Hamers, F.P.T., Steinbusch, H.W.M., and Joosten, E.A.J. (2005), The assessment of locomotor behavior in spinal cord injured rats; the importance of objective analysis of locomotion. J. Neurotrauma 22, 214-225).