'Unicorn puppy' could be hiding a not-so-cute secret
A golden retriever puppy that went viral last week due to the tail growing out of his head could be hiding a less than cute secret.
An expert claimed the tail growing between Narwhal, the 'unicorn puppy's', eyes could really be the remnants of a parasitic twin.
Margret Casal, a professor at the University of Pennsylvania School of Veterinary Medicine, highlighted that a "mohawk" of backward-growing fur located above the tail indicated a twin's rear end.
Casal explained that parasitic twins form when an embryo splits late, and asymmetrically. The result is a fully formed individual, with extra body parts – the remnants of the other twin.
This is not to be confused with conjoined twins where the split happens late in pregnancy and the halves don't fully separate.
If true, this would make Narwal extra special as identical twins are extremely rare in dogs.
The little tail does not wag and has no bones in it, which Casal pointed out is further evidence for the twin theory.
She told the Independent that the bottom of a spine can't develop bones without signals from the top – if Narwhal's appendage is a parasitic twin it could explain why the growth never formed bones.
Michael Levin, who directs the Allen Discovery Centre at Tufts University also thinks a parasitic twin might explain Narwhal, but he said it's impossible to know for sure, as a lot of different factors such as chemicals and environmental factors come into play when bodies form.
"There are massive gaps in our understanding," he said.
"It's a miracle it comes out right most of the time".
Narwal gained viral fame last week after a shelter in Missouri called Mac's Mission shared photos of the distinctive puppy. They claimed he was abandoned due to his appearance.
The rescue organisation, which specialises in what they call "janky" puppies, has been flooded with offers of adoption.
However they are holding on to Narwhal to ensure the tail doesn't grow out of proportion and begin to bother him.