With the exception of only a few very lethal snakes, banana spiders, and fish toxins, I can't think of anything that deadly out there if there is no allergic reaction.
I've never heard of anything that fast either. I think that is one of the reasons Dog Gone was skeptical.
Remember, the evidence is anecdotal. Assuming the report is based on an actual event, it still does not mean the person died from something he caught while slaughtering a pig.