What to Know
If the dog hadn't had a C-section, it's likely the owner never would have known about the twins
Non-identical twins are common in several species, including dogs, but identical twins are far more rare
Pups born in the same litter often look alike and DNA testing is usually not performed, but this is first documented case of identical twins
A veteran veterinarian delivered the first known biologically identical puppy twins in South Africa, researchers who tested the pups' DNA over several weeks confirm.
Kurt de Cramer, who works in South Africa's Rant en Dal ANimal Hospital in Mogale City, was performing a C-section on an Irish wolfhound when he encountered something unprecedented in 26 years of veterinary practice: two puppies with umbilical cords attached to the same placenta, according to British news agency BBC.
The puppies were the same sex and had similar markings; the other five puppies in the litter also looked similar, but each had his or her own placenta, the website reported.
A team of researchers took DNA samples when the pups were 2 weeks old, and again at 6 weeks, and the results confirmed de Cramer's initial hypothesis that they were monozygotic twins.
It's not clear if this is the first case of monozygotic twin puppies, because pups born in the same litter often look alike and DNA testing is usually not performed -- but it's the first documented case in scientific literature.
Non-identical twins are more common because they each have their own placenta. Identical twin fetuses have been reported in horses, for example, but the placenta doesn't have enough oxygen to sustain both.
De Cramer told BBC he saw only one other case of puppies sharing a placenta, but both, oxygen- and nutrient-deprived, were dead before he performed a C-section on the mother.