The tail flick test measures the response to acute thermal pain administered by an infrared heat source in restrained animals. Analgesic compounds such as morphine increase the latency to flick the tail away from the heat source.
Morphine at 5 mg/kg significantly increases the latency to withdraw the tail from the heat source, and this analgesic effect lasts for at least 60 minutes but less than 5 hours.
Morphine dose-dependently increases the latency to withdraw the tail from the heat source in the tail flick test. * - p<0.05 from vehicle control.