If you remember your color chart from school, those shades combine to make green. When the syrup is swirled together with the white ice cream, you get the Shamrock Shake's festive light green ...

They were left shocked when they realised Shamrock remained green. While it is not uncommon for light-coloured pups to have some green on them when born, Shamrock was deep, dark green,” Carole said.

Biliverdin is a green bile pigment found in the womb and can stain fur, especially if the fur is a light color. Carole said Shamrock is currently healthy, happy and has lost most of the tint.