Feral swine are a highly destructive invasive species around the globe. Wildlife managers commonly trap and euthanize feral swine with firearms to reduce their adverse impacts. The utility of euthanizing domestic swine with firearms has been considered when emergency situations arise such as in the event of a foreign animal disease outbreak in domestic swine. Similarly, the rapid depopulation of domestic swine facilities became necessary when the COVID-19 pandemic disrupted pork production in 2020. Evaluation of the effects of caliber, cartridge, size of feral swine, and shot placement on effectiveness and safety of the method is needed. We collected data from feral swine euthanized in traps on how those variables influenced the effectiveness in time to death and number of shots required and safety risks based on the occurrence of bullet pass-through (i.e., bullet exiting the pig). We tested 3 cartridges of 2 calibers (0.22 long rifle, 0.22 Winchester magnum rimfire, and 0.308 Winchester) delivered from a rifle with 3 shot placements targeting the brain. From 570 euthanization events, we calculated an average time to death of 100.06 (SD = 29.24) s, with larger feral swine taking slightly longer. Most feral swine (73%) were euthanized with a single shot but averaged 1.28 (SD = 0.48) shots overall. Safety risks from pass-through shots were more common when using the 0.308 Winchester cartridge, and when rear and side shot placements were used. Overall, we recommend a 0.22 long rifle cartridge and frontal shot placement as an effective and safe option for euthanizing feral swine in traps, and likely for domestic swine of similar size and shot distances.
Keywords: Sus scrofa; disease; euthanization; gunshot; swine; trapping.
Unexpected events such as natural disasters and disease outbreaks can put livestock or free-ranging wildlife in jeopardy, possibly resulting in the need for depopulating numerous animals. During the COVID-19 pandemic, domestic swine production in the United States was disrupted, resulting in the need for refined depopulation efforts. Common euthanization methods were impractical for the scale of the situation and alternative methods were sought. While the use of firearms is an accepted method of euthanization, information on specific suitable firearms and ammunition was lacking. Meanwhile, invasive feral swine are increasingly common across the United States and are routinely captured and euthanized with firearms to alleviate damage to natural and agricultural resources. Although euthanization with firearms is common in field settings, it is unknown whether this would be a safe technique inside domestic swine facilities, considering concerns about bullets passing through a target and ricocheting. We evaluated 3 distinct rifle cartridges on 3 criterion addressing effectiveness and safety while euthanizing feral swine in traps. We found all combinations were effective in euthanizing feral swine averaging <120 s; however, only the 22 caliber did so with minimal potential for risk of pass-through shots on all weights of feral swine.
Published by Oxford University Press on behalf of the American Society of Animal Science 2024.