A review of secondary pentobarbital poisoning in scavenging wildlife, companion animals and captive carnivores

Abstract

Sodium pentobarbital is a veterinary drug commonly employed to euthanize different animal species humanely. Cases of secondary pentobarbital poisoning have been documented in scavenging wildlife, companion animals and captive carnivores. Since the extent of such poisonings remains mostly unknown, a review was undertaken to consolidate cases published, recorded, only locally reported or shared anecdotally. A questionnaire was distributed to veterinary surgery and wildlife rehabilitation centers, and zoos. About 125 cases affecting 432 animals across the US, Canada, the UK, South Africa, New Zealand, Australia, Germany and France were collated, with 76.8% obtained outside the published literature. Our findings support that pentobarbital poisoning affects a range of wild species (e.g., griffon vultures, canids) and companion animals (especially dogs and captive carnivores), and although a known source of toxicosis, pentobarbital-related poisonings continue to present day. Carcass disposal methods were considered in regard to associated incidents of secondary poisoning. Wild scavengers and companion animals were mainly affected after feeding on livestock carcasses that were insufficiently buried or left uncovered. Captive carnivores were accidentally poisoned after being fed pentobarbital-euthanized animals. Euthanized carcasses of stranded whales, provision of euthanized carcasses to dogs at hunt kennels, sourcing of meat from fisheries and laboratories, and use of barbiturates in baits to deliberately harm wildlife emerged as noteworthy sources of risk or exposure. The ongoing presence of pentobarbital residues in pet food as a threat to companion animals was incidentally considered. Additional recommendations for follow-up research, to increase awareness of this issue and prevent exposure, were suggested.

Validation of Multi-Residue Method for Quantification of Antibiotics and NSAIDs in Avian Scavengers by Using Small Amounts of Plasma in HPLC-MS-TOF

“…As a consequence, there is an increasing interest in the risk assessment of pharmaceuticals in scavenger species. To date, several compounds have been found in these species, including residues of antibiotics [13,[15][16][17], antiparasitics [18] and other drugs identified in plasma and tissues as cause of death (e.g., pentobarbital [19,20], ketoprofen [21] and flunixin [19,22]).…”

Developing a European network of analytical laboratories and government institutions to prevent poisoning of raptors

“…This is consistent with the literature on poisoning cases (Berny et al, 2010;Chiari et al, 2017;Grilo et al, 2021;Guitart et al, 2010;Motas-Guzmán et al, 2003;Parvanov et al, 2018;Uros & Andevski, 2018). Barbiturates are pharmaceuticals widely used in veterinary medicine, and they are involved in accidental secondary poisoning (Herrero-Villar et al, 2021;Wells et al, 2020). Nevertheless, our results showed that few laboratories analysed them in Europe (n = 8, 44%), being the group of compounds less frequently analysed (Fig.…”

“…Barbiturates are pharmaceuticals widely used in veterinary medicine, and they are involved in accidental secondary poisoning (Herrero-Villar et al, 2021 ; Wells et al, 2020 ). Nevertheless, our results showed that few laboratories analysed them in Europe ( n = 8, 44%), being the group of compounds less frequently analysed (Fig.…”

“…S2 ). This is the most used pharmaceutical to euthanize domestic animals that may be eaten by scavengers and become a secondary-poisoning source (Herrero-Villar et al, 2021 ; Wells et al, 2020 ). Pentobarbital is well detected in gastric content and the liver (Friend & Franson, 1999 ).…”

Successful medical management of an acute case of pentobarbital toxicosis in a wild bald eagle (Haliaeetus leucocephalus)

“…Acute secondary sodium pentobarbital toxicosis in wild animals has been documented as a cause of acute death in wild, captive and domestic animals worldwide. [9][10][11] A recent review of causes of mortality in bald eagles in the Canadian Maritime provinces between 1991 and 2016 demonstrated that barbiturate toxicoses was the cause of death of 3% of bald eagles presented for postmortem examination during the study period. Though poisoning was a relatively infrequent cause of death compared to other causes, the prevalence may be underestimated, as the presence of poison was not evaluated in all cases of nonspecific clinical signs or unknown cause of death.…”