First identical twin puppies confirmed in South Africa

For the first time, scientists have confirmed the birth of rare identical twin puppies born to an Irish wolfhound in South Africa.
The puppies were first suspected to be twins when, during their birth last year, veterinarian Kurt De Cramer at the Rant en Dal Animal Hospital in South Africa observed that the two puppies had shared a single placenta.
The puppies' mother had been straining to give birth for several hours and was taken to De Cramer, who performed a Cesarean section.
He delivered the mother's other five puppies, each with its own placenta.
De Cramer thought it possible that the placenta-sharing puppies were monozygotic twins. When the puppies were two weeks old, researchers drew blood samples and sent them for genetic testing.

"I wasn't sure that they were going to be monozygotic at that time," Carolynne Joone, a veterinarian and lecturer at James Cook University in Australia told the 'Live Science'.

"They did look very alike, but they weren't completely identical. There were slight differences in the puppies' white markings," she said.
The DNA showed that the puppies had identical genes on 40 different markers that are commonly used in such testing.
A second DNA analysis, done with samples taken from cheek swabs, confirmed that the dogs were identical. The differences in white marking patterns are likely due to differences in gene expression between the two puppies, Joone said.

Since this is the first documented case, researchers think that monozygotic twins in canines are rare, she said.
However, it is also possible that such twins are born more frequently than thought, but go undetected, she added.
The research appears in the journal Reproduction in Domestic Animals.