The purpose of this study is to evaluate the safety and effectiveness of a pain-relieving patch containing the narcotic drug fentanyl in cats undergoing surgery. Cats will be assigned randomly to one of two study groups. Study cats will all be client owned cats undergoing elective onychectomy, with or without spay/neuter. One group will have a patch containing fentanyl placed on the skin, the other group will be given standard pain relieving drugs by injection and orally. Levels of pain will be assessed by using a special pressure sensitive mat to measure weight bearing before and after surgery. This model, using the onychectomy procedure and the pressure mat, provides an objective measure of pain relief that has been difficult to obtain and validate in any other way. Once it can be shown that the fentanyl patch provides significant pain relief, it will be used for many other procedures or situations where felines suffer pain.