These Are the First Identical Twin Puppies Ever Reported in History

De Cramer told BBC Earth he immediately suspected they were twinsies – but he wasn’t sure until he sent blood samples to be analysed by reproductive specialists in South Africa and Australia.

“There have been rumors about twins in dogs before”, she said.

Interesting fact of the day: outside of humans and the nine-banded armadillo, identical twins are pretty rare in the animal world. They had slightly different markings on their paws, the tip of the tail, and chest, and seeing as pups from the same mum often look very similar, he needed more proof.

As the BBC reported earlier this week, the twins, named Cullen and Romulus, were discovered in South Africa by veterinarian Kurt De Cramer, who delivered them via Cesarean section. “It has taken so long for us to find a monozygotic pair, so they are probably rare”, says Joone.

The puppies have subtle differences in the markings in their fur, because although they have the same genes, those genes aren’t necessarily expressed the same way.

‘There have been rumours about twins in dogs before.

“DNA profiles of twins A and B were identical at all 40 genetic markers”, the researchers conclude in Reproduction in Domestic Animals.

The pair are doing well and were the same size as the other five pups by the time they were six weeks old. Because this particular mother happened to have a C-section, the vet was lucky enough to be able to see the shared placenta – but after most dogs give birth, the mother will eat the placentas, which means there would be no clear evidence that any two puppies were twins, Joone explained. They had been born last in a litter of 7 and appeared to be sharing a second placenta.