Outside of humans and one species of armadillo, identical twins seem to be extremely rare. Now for the first time a bitch has given birth to a pair of identical twins in South Africa's Rant en Dal Animal Hospital.
Vet. Dr Kurt de Cramer was performing a Caesarean section on a female Irish wolfhound that showed distress and prolonged abdominal straining when she was due to give birth but noticed something abnormal.
At first Dr Cramer thought the lump was excess fluid surrounding the foetus and then painstakingly extracted the foetus from the bulge by making an incision into the dog's uterus only to find not one, but two foetuses. They were both attached with umbilical cords to the same placenta.
"When I realised that the puppies were of the same gender and that they had very similar markings, I also immediately suspected that they might be identical twins having originated from the splitting of an embryo," says de Cramer.
He could not stop and marvel at this peculiar discovery, because there were still five live puppies to deliver. Cramer says it was the first time de Cramer had delivered two living pups from one placenta in 26 years of practice.
He had to call his team of Animal gynecology specialists who obtained blood samples of the twins when they were two weeks old and confirmed they were twins.
"The twins looked very similar," says Dr Joone Carolynne of James Cook University in Townsville, Australia . "But pups from the same litter often do, [and] there were small differences in the white markings on their paws, chests and the tips of their tails. I wasn't sure they were monozygotic [identical] at all initially."
De Cramer and his team had therefore delivered the first known instance of monozygotic twin dogs and when the twins were six weeks old the team again took DNA samples, this time from their tissue rather than their blood which also confirmed they were identical twins.
It is hard to know, says Joone to BBC. "We are so lucky that this bitch ended up having a C-section," she explains, because otherwise it is unlikely her owners would have noticed.\
"Yes, there would have been one less placenta than there were pups, but as the bitch often eats the placentas the owner probably would have simply shrugged this off. There have been rumours about twins in dogs before," says Joone. "We just happened to be lucky enough to be able to confirm it genetically. It has taken so long for us to find a monozygotic pair, so they are probably rare," says Joone. "But so many of them will have been born naturally and blissfully unaware."More photos...