While the team working with Dogs of Chernobyl was investigating the blue dogs, they came upon an old portable toilet, or porta-potty.

“We are suspecting that this substance was from an old portable toilet that was in the same location as the dogs; however, we were unable to positively confirm our suspicions,” says Betz.

Thanks to the photos of the blue dogs that have a geotag, the team accurately pinpointed the location of the dogs in conjunction with the portable toilet.

Many portable toilets contain a blue liquid that serves as a deodorizer, and they suggest the dogs may have rolled in it. However, until the team can catch and analyze one of the blue Chornobyl dogs, they won’t know for sure what caused the blue fur.