December 16, 2021

Interpretive Summary: Tissue Dimensions Captive Bolt Swine

Interpretive Summary: Tissue Dimensions Captive Bolt Swine

By: Caitlin Vonderohe

Penetrating captive bolt is a commonly used and  humane method for euthanizing swine that weigh less than 200kg. There are also multiple techniques where the captive bolt can be applied frontally, temporally, or behind the ear. A recent study by Anderson et al., published in the Journal of Animal Science, critically examined the use of behind the ear and temporal captive bolt placement for humanely euthanizing mature sows and boars. This is particularly important to explore in large, adult sows and boars because they have greater cranial thickness, developed sinus cavities and a bony ridge that may limit the efficacy of penetrating captive bolt as a euthanasia method. The authors hypothesized that these differences in cranial anatomy would affect the efficacy of the penetrating captive bolt to render humane euthanasia. 

Mature swine cadaver heads were used to explore the effects of captive bolt placement (frontal versus temporal versus behind the ear) and cranial anatomy on the ability of the penetrating captive bolt to sufficiently damage the brain for death to occur with minimal suffering. Digital images of the brain of the cadaver heads were used to assess damage after captive bolt placement, and the degree of brain-bolt contact. 

The greatest amount of consistent brain damage, and the least amount of soft tissue was detected in the frontal placement of the penetrating captive bolt in both sows and boars. As a result, if a penetrating captive bolt is used on a mature sow or boar, it is more likely to be effective as a method of humane euthanasia if placed in the frontal position. However, more studies need to be done to further explore the use of the alternative bolt positions.