Evaluation of intraperitoneal and intrahepatic administration of a euthanasia agent in animal shelter cats

One hundred eighty-one adult cats, with body weight greater than 1.8 kg, were obtained from animal shelters, then were administered a sodium pentobarbital-lidocaine euthanasia agent by either the intraperitoneal (IP; n = 77) or intrahepatic (IH; n = 85) route. A preliminary study (n = 19 cats) indicated that most cats gave no indication of perception of injection (responding) if restraint was minimal and injection was rapid. During IP injection, 3 of the 77 cats (4%) responded (turned the head backward or vocalized). Of the 85 cats given IH injection, 8 (9%) responded; however, no response approached the magnitude of that observed after IM injection of ketamine hydrochloride. After either injection route, cats were observed for excitement (any exaggerated activities of stage-I and -II anesthesia (eg, vocalizing, flopping, sneezing, licking, running, paddling), and after cardiac standstill, cats were necropsied to identify exact location (final site) of the injection. Of 53 initial IP injections, final site for 22 (42%) was in the peritoneal cavity (PC). Use of a sideport needle (n = 24) did not significantly increase accuracy of IP injection. The small and large intestines were penetrated by 27% (15/55) of the IP injections from the right side, and the spleen was penetrated by 32% (7/22) of the left-side injections. Intrahepatic injection was significantly (P less than 0.05) more accurate, with 70 of 85 (82%) of the final sites being the liver only, the liver/PC, or the PC only. Twenty-five percent (13/53) of IP injections resulted in excitement (all stage-I and -II anesthesia-exaggerated activities cumulative to 30 seconds).(ABSTRACT TRUNCATED AT 250 WORDS)