Meet the First Identical Twin Dogs on Record

· March 9, 2019
The first identical twin dogs were born in South Africa. In today's article, we'll tell you more about these two dogs and how they were discovered.

Cullen and Romulus were the first confirmed identical twin dogs on record. These Irish Wolfhound puppies were born in South Africa. They both shared the same placenta and were part of a litter of 7 puppies. 

Discovery of the first confirmed identical twin dogs

The discovery took place in the city of Mogale, South Africa. Since the mother was having complications giving birth, veterinarian Kurt de Cramer decided to perform a cesarean section on her.

However, at the beginning of the surgery, the vet noticed that the mother had a strange bulge in her uterus. He initially just attributed it to an excess of fluid surrounding the fetus.

Much to the doctor’s surprise, however, there were two puppies in the same placenta!

Meet Romulus and Cullen, the first identical twin dogs on record. The dogs were part of a litter of 7 puppies born by cesarean section in Mogale, South Africa. 

Cullen and Romulus, the twin puppies

Identical twin dogs playing.

De Cramer—a specialist in gynecology and animal reproduction—suspected right away that he was dealing with a case of identical twin dogs. However, in his 26 years of work, he had never encountered a case like this. Because of that, he contacted a group of colleagues to tell them about his findings.

The team included Carolynne Joone (James Cook University of Townsville, Australia) and Johan Nöthling (University of Pretoria, South Africa). These experts did blood tests on Romulus and Cullen when they were two weeks old. 

In doing so, they were able to confirm that the puppies were genetically identical, even though they had a few differences on their fur. They then published the good news in Reproduction in Domestic Animals. 

More analysis to confirm the identical twin dogs

Then, when the puppies turned six weeks old, the professionals took tissue samples to analyze their DNA. They also took samples from their other siblings.

And, once again, the scientists proved that Cullen and Romulus are genetically identical. On the other hand, the other puppies only had levels that are usually found within puppies of the same litter. 

So, they cleared up any doubts they had about the small differences in the spots on their legs, chest and tail. The explanation for those differences is that, despite having the same DNA, genes can manifest themselves in different ways. For example, identical twin humans have different moles and fingerprints.

Are there no other cases of identical twin dogs?

After this discovery, a lot of people began to wonder if identical twin dogs were really that uncommon. 

Female dogs often give birth to puppies that are extremely similar to each other, but:

  • It’s not common to do a DNA analysis
  • Vets don’t always do cesarean sections, so they can’t see the number of placentas
  • It’s normal for the mother to eat the placenta after giving birth

So, although this is the first confirmed case of identical twin dogs, scientists cannot determine if this case is really that uncommon. However, all evidence seems to show that it’s not very common.

Are twins common in the animal world?

Two puppies with their mom.

Normally, identical offspring aren’t common, except in humans and some armadillos.

This is because when two fetuses share the same placenta, they usually don’t get enough nutrients and oxygen to survive. Because of that, they’re less likely to survive.

As for Romulus and Cullen, although at birth they were smaller than the rest of the litter, they are now living happily with their mother and siblings.