When a litter of puppies is born, you don't always know what's going to come out. Sometimes they are all clones of each other, other times they look completely different and, every so often, there's a green one.

Yes, you read that correctly. From mint to bright lime, green puppies have been surprising dog owners all over the world. Recent news stories have featured a German Shepherd named Hulk from North Carolina, a Labrador Retriever named Fifi (after Shrek's Princess Fiona) from England, a Great Dane named Verdant from Colorado and Golden Retriever named Forest from Scotland (pictured below).

The reason for their uncommon hue is simple: poop. When dogs have light-coloured fur, it can get dyed by meconium which is the puppy's first #2. The meconium won't affect every member of the litter, however. Each puppy hangs out in its own sac while their mom is pregnant so a "dying agent" in one sac will not spread to the others.

Meconium is not harmful for puppies and its effects are not permanent. Dog owners who have witnessed the phenomenon say that the green colour fades over time. It's just another quirk of breeding dogs along with litters that contain entirely different breeds. Because it's possible for a litter to have multiple fathers, some puppies can be full-breeds while others are mixed.

If you want to dye your dog green, that's another story entirely. Although we don't recommend it, we love this story of a Pomeranian named Harvey Moon who prefers to be brightly coloured (or so his owner says). You can, if you really want to, safely dye your dog by only using pet-friendly dyes, non-toxic food colouring or fur chalk. Make sure to keep dyes away from sensitive areas (mouth, nose, ears) and consult your groomer or vet beforehand.

Would you ever dye your dog? Let us know in the comments or tag us @pawzyco on Facebook, Twitter and Instagram.