Opioids are commonly used for the treatment of pain in cats. While they are considered to be highly efficacious, one main disadvantage to their use is their relative short duration of action, and therefore the need for repeated administration. Fentanyl is a potent opioid with a short duration of action. It is commercially available in patches, which are applied on the skin and provide continuous release for up to three days. They are therefore expected to produce continuous pain relief, with a single, non-invasive administration. While fentanyl patches are commonly used to treat pain in feline patients, their analgesic effect has not been studied using objective methods, leading to uncertainties as to onset and duration of effect. This is important, since practitioners using these patches may rely on the effect, and may not have the opportunity to reassess their feline patients often enough to detect inadequate analgesia early. The study proposed here will examine the effect of fentanyl patch application on an established model of pain in cats.