Rio, a 3-year-old golden retriever, recently gave birth to a puppy whose fur was green.

The color started to fade pretty quickly, but not before the mint-green puppy, Forest, made a splash online.

Rio's owner, Louis Sutherland, was shocked to find that one of the nine puppies stood out, The Sun reported.

"We couldn’t believe it," she said. "When we checked it out later, we found out it is very unusual and to do with the placenta. The color has faded quite a bit already and will be gone soon, I’m told. We’ve named him Forest.”

Bile pigment found in the placenta of dogs can stain the puppy's coat green when it mixes with the amniotic fluid, The Sun reported. Green puppies have only been recorded three times before in the world.