**3. Results**

All 12 guinea pigs failed to show signs of corneal blink, righting reflex, audible vocalization, head/neck tension and rhythmic breathing immediately after the initial shot. Based on these criteria, all guinea pigs were considered to have been stunned and rendered unconscious immediately. No additional shots were required for any of the guinea pigs. Exsanguination via severance of the lower abdominal aortic vessel was performed within 20–30 s of the initial shot to ensure death. A few of the guinea pigs were seen to display signs of involuntary muscle fasciculations and slow hindlimb pedaling motions, which lasted for less than 30 s. The bolt produced cranial skull fractures with associated subcutaneous hemorrhages, but the overlaying skin remained intact. While there was no evidence of puncture or bleeding overlying the site where the bolt penetrated the skull (Figures 3 and 4), there was a discrete palpable, circular depression in the cranium the size of the captive bolt diameter. Mild epistaxis (*n* = 3) was seen post-CBE. Informal debriefing with the operators (*n* = 8) and researchers (*n* = 4) suggested they all favored CBE over the BFT method. They stated CBE had a greater yield of higher quality uncontaminated tissue and was less physically, emotionally and compassionately fatiguing than BFT [52].

**Figure 3.** Skin intact from penetrative CB site.

**Figure 4.** Skin removed from penetrative CB site.
