Allometric method for the long term observation of adjuvant arthritis in rats.

An allometric method for estimating the volume change in inflamed paw of rats is described. The technique is effective and advantageous for long term observation of adjuvant arthritis which lacks a suitable reference criterion due to the simultaneous swelling of the control paw. In the present method, the inflammatory intensity (IF) of paw edema is estimated by means of the formula; IF(%)=(2Vr/cXd(I+Wt/aXb)-I) X 100 where Vt is the paw volume, Wt is the body weight weight and X is the tail length of the inflamed rat. The constants a, b, c, and d are obtained from tthe normal rats using the relative growth law, W=aXb and V=cXd (where W is the body weight, V is the paw volume and X is the tail length).