South Africa is now home to the first-ever case of canine identical twins.
Dogs are usually born with their own individual placentas, so you can imagine Dr. Kurt de Cramer's surprise when he was delivering puppies in the Rant en Dal Animal Hospital in Mogale City, South Africa and two puppies in the litter were sharing a placenta.
When an Irish wolfhound came into the clinic with a strange bulge in her uterus causing abdominal strain, Dr. Cramer initially thought it was excess fluid around the multiple fetuses. He initiated a routine caesarean section and was shocked to find two fetuses attached to the same placenta.
Five more puppies were born in the litter, each with their own placenta. But the puppies sharing a placenta were an anomaly.
"When I realized 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 Cramer.
This was the first time Dr. Cramer had witnessed true sets of twins from a canine birth so he immediately alerted experts in the field. Carolynne Joone of James Cook University in Townsville, Australia and Johan Nöthling of the University of Pretoria in South Africa came to visit the twin pups to get blood samples.
"The twins looked very similar," says Joone. "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."
Because Cramer witnessed the pups being born attached to the same placenta, he could confirm that the pups are, in fact, identical twins, despite the slight differences in their markings on their chests.
The differences can be explained by the fact that individuals have certain genetic alterations even though they have the same DNA.
"Human identical twins also have the same genes, but because those genes are expressed differently in each person, they have different freckle and fingerprint patterns," explains Cramer.
It is debated if this is really the first set of twins in dogs. Mother dogs usually eat the placentas after giving birth, making it hard to tell if puppies are attached to the same placenta. In this case, it was lucky that Dr. Cramer witnessed the Irish Wolfhound's birth since it was a cesarean section.
It was also lucky the pups survived.
"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," Cramer says.
Identical births are rare in the animal world. Humans and a rare breed of armadillos are the only mammals to have truly identical twins.
Images via Kurt de Cramer via the BBC