**Background:** Giant Pacific octopuses (*Enteroctopus dofleini*, GPOs) are popular exhibit animals in zoos and aquariums, yet evidence-based guidelines for their sedation, anesthesia, and euthanasia are limited. Most available data come from smaller cephalopod species, and veterinarians may be reluctant to perform procedures due to uncertainty about best practices. This study aimed to characterize current husbandry and veterinary care practices, with a focus on anesthetic and euthanasia protocols, through an online survey of aquatic professionals.
**Methods:** A two-part web-based survey was created using Qualtrics and distributed to four email listservs (IAAAM, AAZV, WAVMA, and [email protected]). Phase 1 (11 November 2020 – 21 April 2021) was open to any North American institution that currently or historically housed cephalopods; 52 institutions participated. Respondents provided information on whether they currently house GPOs, habitat volume, water temperature, life support system type, and whether they had ever sedated or anesthetized a GPO. Those who answered “yes” to currently housing GPOs or having housed them in the last five years were invited to participate in Phase 2 (24 November 2020 – 19 January 2021), a more detailed survey on husbandry, veterinary care, sedation, anesthesia, and euthanasia techniques. Phase 2 received 25 responses (63% response rate from 35 invitations). Data were reported as averages, medians, modes, and percentages.
**Key Results:** In Phase 1, 40 of 52 institutions (78%) currently housed GPOs. Most (70%) housed one GPO, 27% housed two, and 3% housed three. Median habitat volume was 5405 L (range 1893–16,389 L), and 78% of systems were closed. Average water temperature was 10°C (range 8.8–14.4°C). Twenty-three institutions (62%) reported having sedated or anesthetized a GPO for any reason (including euthanasia). In Phase 2, 20 of 22 respondents (91%) acquired GPOs commercially or through donations; none reported hatching in human care. Feeding frequency ranged from twice daily to twice a week, with 56% feeding 3–5 times per week. Only 48% of institutions performed quarantine, typically for 30 days. Veterinary visual examinations occurred at entrance (71%), necropsy (67%), only when needed (52%), and preventatively (48%). Eight institutions (38%) had performed non-euthanasia procedures in the last two years, including biopsies (n=6), hemolymph collection (n=2), skin scrapes (n=2), ultrasound (n=2), radiographs (n=1), physical examination (n=1), skin culture (n=1), and wound care (n=1). Of these, 75% used sedation or anesthesia. For sedation/anesthesia, the most common agents were magnesium chloride (33–47 g/L, n=9), ethanol (0.03–3.0%, n=6), isoflurane (n=2), MS-222 (100 mg/L, n=2), magnesium sulfate (n=1), benzocaine (500–2000 mg/L, n=1), and dexmedetomidine (n=1). For euthanasia, agents included magnesium chloride (20–200 g/L, n=13), ethanol (5–27%, n=9), mechanical decerebration (n=4), pentobarbital (n=2), isoflurane (n=1), MS-222 (n=1), magnesium sulfate (n=1), benzocaine (>2000 mg/L, n=1), potassium chloride (n=1), dexmedetomidine (n=1), and freezing (n=1). Reported negative experiences included inadequate sedation, inking, prolonged recovery, and behavior changes. Induction times for ethanol ranged from 2 to 20 minutes, recovery from 10 to 45 minutes, with longer times in colder water. For magnesium chloride, induction was 28 minutes, immersion 45 minutes, and recovery 60 minutes at 33 g/L. Time to unresponsiveness with magnesium chloride for euthanasia ranged from 20 minutes to 2 hours. Pentobarbital was reported ineffective in one case (20 mL not effective).
**Clinical Implications:** This survey reveals that GPOs are commonly housed in North American institutions, and a majority have used sedation or anesthesia for nonterminal procedures. However, the wide variability in drug doses and methods, along with reported side effects, underscores the lack of standardized protocols. Magnesium chloride and ethanol remain the most common agents, but their effectiveness is influenced by water temperature, animal size, and health status. The findings highlight the need for prospective studies to establish safe and effective anesthetic protocols for GPOs, particularly given the growing interest in cephalopod welfare and the inclusion of cephalopods in animal welfare legislation (e.g., UK Animal Welfare Sentience Act 2022). Improved anesthesia techniques could facilitate diagnostic procedures (e.g., gill biopsies for branchitis) and humane euthanasia, ultimately enhancing the welfare of this species in human care.