Though the image etched into her retinas bespoke a Lovecraftian horror, Williams kept her cool, recalling previous reconnaissance into canine pigmentation aberrations.

“Luckily, I had recently read an article about a green dog. So at least I knew what was going on.”

Apparently, this whole chlorophyll-colored pup thing isn’t as uncommon as you might think. CNN reported a similar case in 2017, attributing the cause to “biliverdin,” a pigment found in bile, and the same pigment that causes that Grinchly shade of green in bruises.

If a dog comes into contact with biliverdin in the womb, it can basically dye their fur that color, not unlike how you might color an Easter egg — just a little less festive. The good news is that green in the womb doesn’t spell doom for a puppy, as it’s mostly a cosmetic issue, and that the coloration will usually fade within a couple weeks.

Biliverdin in the womb is natural, and a green pup likely just points to a higher amount than would usually be present. While research on the subject is scant, it appears that biliverdin plays an important role in neonatal development and wellness for a variety of creatures, according to ScienceDirect, with a wide range of antioxidant and pigmentation properties. Being born Hulk-hued seems to be an issue specific to dogs, though.

So if you ever come across a green puppy, keep calm and name it something more creative than “Hulk” or “Forest,” cause out of the handful of documented cases, those names have already been taken.