2.3 Edema measurement
Paw thickness was used as a measure of inflammation-induced edema (Buritova, Honore & Besson, 1995; Wei, Zou, Young, Dubner & Ren, 1999). The dorsoventral thickness of each hind paw was measured with a digital caliper. The caliper was placed at the metatarsophalangeal border and touched, but did not squeeze, the hind paw. Contralateral paw thickness was used as a control measure.