Some neurobehavioral effects of ketamine in chicks

The neurobehavioral effects of ketamine 0.5 and 1 ml/kg subcutaneously were examined in 14 days-old domestic chicks using the open-field (5 minutes) and tonic immobility tests. Ketamine decreased locomotor activity as seen by a significant increase in the latency to move from the central square of the open-field arena and a decrease in the numbers of lines crossed (0.5 mg/kg, 30 and 60 minutes post injection) in comparison with control values. Ketamine also decreased vocalization behavior. The depressed open-field activity was further supported by significant increases in the durations of tonic immobility of the ketamine- treated chichs in comparison with the control group. Xylazine challenge at 5 mg/kg, subcutaneously, two hours after the ketamine injections signifantly increased the duration of sleep in both ketamine-treated groups by 59% and 100%, respectively in comparison with the control group. The data suggested that ketamine at subanesthetic doses reduses open-field activity in chicks, increases tonic immobility and increases the sedative action of xylazine.