When a pair of ranchers in Northern California cut open a wild pig they shot on their land recently they did not expect to see bright blue fat throughout. Few hunters have ever seen such a thing.

The couple’s son-in-law posted photos and an explanation to Imgur this week, it raised all kinds of suspicions on-line. Could it be an alien race of hogs? Maybe the hog ate a whole truckload of M&Ms or possibly blueberries. 

In an attempt to solve the mystery, the family from Morgan Hill outside San Jose had a portion of the flesh sent to UC Davis researchers for examination. Blue pigmentation can reportedly be the result of copper poisoning, but there was no obvious source of copper on the ranch — only old mercury mine shafts that had been filled in.

The most likely explanation is that the pig ate a large amount of rat poison over time, not enough to kill it but enough to turn its fat tissue blue. It may have either consumed poisoned feed or rodents themselves, which had eaten the poison.

A paper on anticoagulant rodenticide intoxication by UC Davis researchers states that “although uncommon, some AR baits contain a dye that causes a marked color change of fat and tissues in animals after ingestion.” 

This sort of unintended exposure to rat poison has led the US EPA to place greater restrictions on the use of such substances. In most cases, hunters are told that what they might discover within an animal shouldn’t make them sick. But this case is different. Experts warned against consuming any of this blue hog.

Photo credit: Imgur