A pair of dog breeders from Vallodolid, Spain were shocked when they noticed that new members of their latest litter were born green.

Initially thinking it could be washed off, Aida Vallelado Molina, gave them a good scrubbing, but to no avail. 

The Local reports that the puppies, who were born last week, were noticeably weaker than the rest of the litter, with one dying shortly after birth and the other still very weak. 

Vet Daniel Valverde is currently running a variety of tests to determine the cause of this rare condition. 

A similar case was reported by the Daily Mail two years ago, when the colour was found to have been caused by bile mixing with amniotic fluid in the womb. In that instance, the colour faded after a few days.