Two Irish wolfhounds named Cullen and Romulus are reportedly the first-ever confirmed identical twin puppies to have come into the world.
Their birth occurred back in October, but scientists chronicled this biologically identical canine discovery in the just-published issue of the Reproduction in Domestic Animals journal in which they concluded that “To the best of our knowledge, this is the first report of confirmed monozygotic twinning in the dog.”
Although twin puppies may have been born before, this is apparently the first documented/recorded case as supported by DNA analysis, which apparently is otherwise seldom performed on a litter of puppies.
The vet who delivered the fraternal twin puppies via cesarean section for a mother who had an unusual bulge in her uterus in the South African municipality of Mogale City was amazed to find that they were both sharing the same placenta.
“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,” Dr. Kurt de Cramer, who performs about 900 C-sections each year but never saw one like this, told the BBC.
He alerted reproductive scientists who took blood samples from Cullen and Romulus about two weeks later and “the results confirmed what de Cramer had suspected: the dog had given birth to two identically genetic puppies.” Follow-up tissue testing four weeks after that once again confirmed that Cullen and Romulus were identical twins.
Cullen and Romulus have five similar-looking siblings who were delivered in the same litter, but none of them are twins, and each had their own placenta. The twins were somewhat smaller than their littermates when they were born, but caught up to their siblings after six weeks.
The vet added that in 26 years of practice “he had only seen one other case of two fetuses sharing a placenta…and the fetuses were already dead when he performed a cesarean section.”
“People have suspected for years that identical (monozygotic) twins are possible in domestic dogs, and there have been anecdotal reports, but there has never been a confirmed case in the scientific literature until now,” National Geographic explained about the uniqueness of the South African Irish wolfhounds puppies.
According to Life Science, the healthy canine puppies were still identical notwithstanding the fact that each had some subtle differences in markings on their paws, chests, and tail, similar to the way human identical twins may have different freckles or moles or fingerprints.
“There were slight differences in the puppies’ white markings. But 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, [Dr. Carolyn] Joonè said.”
Researchers believe that one of the reasons why identical twins are so rare in nature is that “they put such an incredible strain on the mother by having to fit into the same placenta, and then share nutrients throughout the pregnancy, it’s thought that many don’t make it to term,” Science Alert detailed.
Another theory is that maybe no human was around at the time of the birth and thus the occurrence never making it into the scientific literature. “Just because these little wolfhounds are the first ever identical twin dogs known to science doesn’t mean there haven’t been others that have gone unnoticed.”
“There have been rumors about twins in dogs before.We just happened to be lucky enough to be able to confirm it genetically,” Dr. Joone told the BBC, noting the C-section birth led to the discovery, since female dogs often eat the placentas after giving birth.
Hopefully when the times comes, the identical Irish wolfhounds can be adopted out together with the same family.
[Image via Shutterstock]