INFLUENCE OF ANESTHETIC REGIMENS ON THE PERIOPERATIVE CATECHOLAMINE RESPONSE ASSOCIATED WITH ONYCHECTOMY IN CATS

Plasma catecholamine concentrations in response to onychectomy were ex amined in 27 cats receiving different anesthetic regimens. Each cat wa s anesthetized with a dissociative-tranquilizer combination, and onych ectomy was performed on 1 forefoot. One week later, each cat was anest hetized with the same dissociative-tranquilizer combination plus eithe r butorphanol or oxymorphone, and onychectomy was performed on the oth er forefoot. Four treatment groups were studied: tiletamine-zolazepam and tiletamine-zolazepam-butorphanol combinations were administered to group-1 cats, ketamine-acepromazine and ketamine-acepromazine-butorph anol combinations were administered to group-2 cats, tiletamine-zolaze pam and tiletamine-zolazepam-oxymorphone combinations were administere d to group-3 cats, and ketamine-acepromazine and ketamine-acepromazine -oxymorphone combinations were administered to group-4 cats. All drug combinations were administered IM. Central venous blood samples were d rawn for catecholamine analysis after injection of drug(s), after onyc hectomy, and 1, 2, and 4 hours after injection. Tiletamine-zolazepam a lone or tiletamine-zolazepam-butorphanol prevented epinephrine release for 2 hours after injection of drug(s). Norepinephrine concentration increased significantly (P < 0.05) from baseline after onychectomy for tiletamine-zolazepam-butorphanol and at 4 hours for tiletamine-zolaze pam and tiletamine-zolazepam-butorhanol. After onychectomy, there was no difference in epinephrine values between tiletamine-zolazepam and t iletamine-zolazepam-oxymorphone. Ketamine-acepromazine prevented incre ases in norepinephrine and epinephrine concentrations for up to 2 hour s after surgery. Addition of butorphanol to ketamine-acepromazine decr eased norepinephrine values immediately after onychectomy. Addition of oxymorphone to ketamine-acepromazine resulted in lower epinephrine va lues 4 hours after surgery.