Effects of Delta–9–tetrahydrocannabinol on Halothane MAC in Dogs

The effects of acute and subacute administration of delta–9–tetrahydrocannabinol (THC) on halothane requirements (MAC) in four groups of dogs were measured. THC administered intravenously produced a dose–related alteration in MAC. THC, 0.1 mg/kg, did not alter MAC 1, 3, or 24 hours after its administration. THC, 0.5 mg/kg, decreased MAC 32 per cent (P < 0.05) 1 hour after injection, but MAC was not significantly different from control after 3 and 24 hours. MAC was decreased 42, 36, and 18 per cent (P < 0.05) from control 1, 3, and 24 hours after 2.0 mg/kg THC. MAC was not changed from control 24 hours after four daily injections of 0.5 mg/kg THC.