The unusual phenomenon occurred in North Carolina, US on Friday, when a white German Shepherd named Gypsy gave birth to a litter of eight puppies.
The dog was in labour for three hours, her owner, Shana Stamey, told local news station WLOS.
Everything about the birth occurred as one could have expected, apart from when the fourth puppy made his arrival.
The puppy was peculiarly born with lime green fur, an occurrence that may have happened due to the “meconium” in the mother’s womb, which is the earliest stool produced by an infant mammal.
"The puppy's green hue is likely to have been caused by meconium, a puppy's first faeces which may be passed ahead of birth, or placental pigments," Daniella Dos Santos, president of the British Veterinary Association, tells The Independent.
"In any case, this should fade over time."
Ms Stamey said that while she knew the colour of the puppy’s fur “wasn’t harmful” she “had to look it up again to make sure”.
“Mum licks it away until I bathe it and then, I guess after a couple of weeks, it will finally fade out,” she said.
The owner revealed she and her family decided to name the infant “Hulk”, after the green Marvel comic book character.
“Hulk! It was lime green. He was super mad. So, yeah, he became Hulk,” she stated.
Her family considered other names for the puppy, including Gremlin and Pistachio.
However, as the puppy’s fur has now turned a more yellowish shade, he has also been nicknamed Pikachu, after the yellow Pokémon.
In July 2017, a Golden Retriever in the Scottish Highlands, gave birth to a litter of nine puppies, one of which came out with green fur.
It was believed that the puppy’s unusual shade of fur was caused by a bile pigment called biliverdin, found in the placenta of dogs, mixing with the amniotic fluid.