A new apparatus for measuring diameter changes of the rat paw and tibiotarsal joint.

A new apparatus for the study of hind-limb inflammation in the rat is described. It measures with high precision the diameters of the hind paws and tibiotarsal joints at anatomically well defined reference points. Inflammation induced by subplantar carrageenin injection and by inoculation of adjuvant in the tail is accompanied by readily detectable and pronounced increases in diameters. Results obtained with this rapid and simple method are reliable and the method offers practical advantages over volume measurements.