Drug options to provide analgesia in cats are limited, especially when oral administration is required. Drugs that are commonly used in other species, such as opioids, non-steroidal anti-inflammatory agents, alpha-2 agents, the dissociative, ketamine, and local anesthetics often produce side effects in cats. Tramadol is an orally administered, centrally acting analgesic drug that interacts with opioid, adrenergic and serotonin receptors. It has been shown to be efficacious and well tolerated in people and dogs. Although tramadol is currently used in cats, no scientific data support this use. Its pharmacokinetics are unknown in that species, making rational dosing recommendations impossible. Its duration of action is also unknown. Although it appears to improve pain clinically, no objective data on efficacy in cats are available. In this study, we propose to determine the pharmacokinetics of tramadol in cats. We will then characterize its analgesic effects, the dose-dependence of these effects, and their duration using a thermal threshold model. This study will allow the recommendation of optimal dosing regimens, both in terms of dose and dosing interval.