Stereotypic behavior, endogenous opioids, and postfeeding hypoalgesia in pigs

Tethered sows, some of which performed marked behavioral stereotypies after feeding, were injected IM with 1 mg/kg of naloxone 30 min before feeding (with 2 saline control days). Tail-flick latencies on a pain-sensitivity test were recorded before and after feeding. On control days, tail-flick latencies after feeding were longer than those before feeding, and this […]