The puppies, born in South Africa, make dogs only the third species capable of producing monozygotic twins
In what is believed to be the first pair ever recorded, two puppies born in October have been proven to be identical twins after genetic tests proved they share the same DNA. The Irish wolfhound puppies, born in South Africa, now suggest that dogs are only the third species capable of producing identical twins, after human beings and nine-banded armadillos.
The dogs, named Cullen and Romulus, were first identified as potential twins by South African vet Kurt De Cramer, who delivered their mother’s litter by Caesarean section. While the average female dog will usually deliver five to six puppies per pregnancy, Cullen and Romulus shared a single placenta, a rare occurrence which typically results in both puppies dying shortly after birth.
“It is even less likely for placenta-sharing puppies to survive, because of several complications relating to nutrient and oxygen supply from a single placenta having to do the job that is normally done by two placentas,” De Cramer told the BBC. But the puppies have since thrived, reaching a similar size to the five other puppies from their litter despite starting out as the runts.
Blood and DNA samples were taken from the two dogs at six weeks to determine once and for all whether they were monozygotic twins, have once been the same fertilised egg. Puppies in litters often look very similar, and Cullen and Romulus did have some slight differences in markings on their tails and paws. Working with a veterinary researcher at Australia’s James Cooke University, the pair was finally confirmed as the world’s first recognised identical twin dogs.