Use Of Potassium Chloride For Low-Residue Euthanasia Of Anesthetized California Sea Lions (Zalophus Californianus) And Northern Elephant Seals (Mirounga Angustirostris ) With Life-Threatening Injury Or Disease

OBJECTIVETo demonstrate the efficacy of potassium chloride (KCI) for low-residue euthanasia of anesthetized pinnipeds in field settings for which carcass retrieval for disposal is not feasible.ANIMALSStranded, free-ranging California sea lions (CSLs; Zalophus californianus; n = 17) and northern elephant seals (NESs; Mirounga angustirostris; 6) with life-threatening injury or disease between May and August 2020.PROCEDURESEach animal was anesthetized and then received a lethal dose of KCI solution administered by IV or intracardiac injection. The effective KCI dose; durations to cardiac arrest, respiratory arrest, and pupil dilation; and presence or absence of agonal breaths, muscle fasciculations, or skeletal movements were recorded.RESULTSMean effective dose of KCI was 207.4 mg/kg (94.3 mg/lb) for the 17 CSLs and 209.1 mg/kg (95.0 mg/lb) for 5 of 6 NESs (1 outlier NES was excluded). The range in duration from the beginning of KCI injection to cardiac arrest was 0 to 6 minutes, to pupil dilation was 0 to 5 minutes, and to respiratory arrest was 0 to 5 minutes. Muscle fasciculations, skeletal movements, and agonal breaths were observed in both species during and after KCI administration.CONCLUSIONS AND CLINICAL RELEVANCEThe use of KCI provides an effective, low-residue method of euthanasia in anesthetized CSLs and NESs. Our recommended dose for these species is 250 mg KCI/kg (113.6 mg KCI/Ib) delivered by intracardiac injection. Compared with euthanasia by barbiturate overdose, the use of KCI reduces the potential for secondary intoxication of scavengers and is appropriate in field scenarios in which the carcass cannot be retrieved for disposal.