A pair of dog breeders in Spain have spoken of their shock after one of their dogs gave birth to a litter of pups – two of which were born with bright green coats.

The puppies were born on 3 June, but unlike the rest of the litter, had a visible green tinge to their coat.

Both puppies were weaker than the rest of the litter and the female died shortly after birth, Aida Vallelado Molina, 27, who breeds hunting dogs with her father in the town of Laguna de Duero, told The Local. The other, a male, is alive but is still weak and is losing his pigmentation.

Download the new Independent Premium app Sharing the full story, not just the headlines

"I thought the puppies were dirty and tried to clean them, but the colour wouldn't come off," Ms Molina said.

"I couldn't believe it when I first saw them."

Daniel Valverde, a local vet, is now investigating the cause of its death and why it was born such an unusual colour and plans to conduct virological and bacteriological tests on the animals.

Shape Created with Sketch. In pictures: Dog gives birth to green puppies Show all 8 left Created with Sketch. right Created with Sketch. Shape Created with Sketch. In pictures: Dog gives birth to green puppies 1/8 Green puppies 2/8 Green puppies 3/8 Green puppies 4/8 Green puppies 5/8 Green puppies 6/8 Green puppies 7/8 Green puppies 8/8 Green puppies 1/8 Green puppies 2/8 Green puppies 3/8 Green puppies 4/8 Green puppies 5/8 Green puppies 6/8 Green puppies 7/8 Green puppies 8/8 Green puppies

"There are no other recorded cases of this happening in Spanish scientific literature," he told local newspaper Laguna al Día after contacting Madrid's Complutense University.

A similar case was reported in the UK in 2012 when a golden Labrador gave birth to a puppy named 'Hulk', which also had a green tinge to its coat.

Experts said the animals could have been exposed to a substance called biliverdin, which can be found in the placenta and is sometimes responsible for the greenish hue often seen in bruises.