Abstract
A low cost infrared skin heating system has been designed to measure the efficacy of analgesics in rabbits. Following construction of a prototype, it was used to assess the effect of buprenorphine given subcutaneously and per rectum. Buprenorphine administered subcutaneously has a rapid onset of action, but its duration (8-10 h) appears slightly shorter than has been suggested previously; rectal administration appears to prolong its effect. Preliminary data show that lofentanil has a longer duration of action than buprenorphine and it may prove, therefore, to be a valuable long-acting analgesic in the rabbit.