Experts Solve The Mystery Of Yuki, The Shelter Dog That Wouldn’t Stop Growing

It was 2008, and Yuki's original owner was getting desperate. The small, shivering puppy they'd once rescued had transformed into a wild, snarling creature. The owner couldn't get Yuki to sit, let alone keep him on a leash and away from other people. It was like Yuki was another dog entirely.

To make matters worse, the gray-matted puppy wasn't really a "puppy" anymore. The energetic dog was getting too difficult for one person to control, and that alone was enough to make the owner seek outside help...that is, until he noticed another startling trait.

At eight-months, Yuki had grown to a bigger size than his owner could ever have expected. Of course puppies grow, but this much so soon was alarming enough that his owner decided to wipe their hands clean of the matter and make Yuki someone else's problem.

The owner dropped Yuki off at an animal shelter in hopes that they could find him a more suitable home. The shelter had seen all kinds of badly-behaved pups and wild animals in their time, but it soon became clear that they were no match for Yuki. So, they called in the big guns.

They knew of a nearby shelter that specialized in taking care of animals that other shelters couldn't handle. Owned by Kent and Nancy Smith, the animal shelter's staff and volunteers had overseen the most unruly animals, from badly-behaved dogs like Yuki to bobcats and cougars.

Settled in Naples, Florida, Kent and Nancy's shelter, Shy Wolf Sanctuary, has helped over 1,200 creatures in need. More than that, the Smiths have emphasized an educational approach to better unify humans with animals. They had no idea then how little they were prepared for an animal like Yuki.

Two staff members from Shy Wolf Sanctuary traveled over to bring Yuki to his new home. The gray dog needed special care and people who could actually understand him, and the staff members knew they were the best people for the job...until they met him face to face.

They'd been told that Yuki was a tough case, but it was still unnerving to see young Yuki thrashing around in fear when they approached. When he wasn't baring his teeth at them, he was glaring at them with small, yellow eyes. Of course, what really struck them as odd was his size.

For being only eight-months old, Yuki was big — weirdly big. One look at him and Kent and Nancy knew they weren't dealing with a normal pup. So, they arranged for Yuki's DNA to be tested. While they waited for the results, their hunch that something was up with Yuki was only reinforced by his behavior.

Yuki definitely didn't have the friendly, "man's best friend" attitude of other dogs. He was erratic at best and violent at worst, though he slowly got more comfortable at the sanctuary as time went on. Still, the sanctuary's staff tried to domesticate him...until an accident made doing so impossible.

When Yuki unexpectedly wounded his right knee against a palmetto, he needed five surgeries to fully heal. The painful experience only made poor Yuki even more unpredictable. Throughout that period, he became very particular about who was allowed into his cage.

It became apparent that the few staff members Yuki liked were women. When comfortable, Yuki could even manage to sit on one of their laps for a cute Instagram moment! Those moments were rare, however. Most of the time, the staff simply tried to figure out why he wouldn't stop growing.

When the DNA tests finally came back, the staff didn't know what to expect. As the owners of Shy Wolf Sanctuary, Kent and Nancy definitely had a feeling that Yuki's dog-like appearance didn't tell his entire story. And when they analyzed Yuki's DNA, they saw just how right they were.

Yuki had German Shepherd and Siberian Husky in his genetic makeup. With his inquisitive yet protective nature, this made sense, though the German Shepherd and Siberian Husky genes were only a fraction of his DNA. As it turned out, the other 87.5% of Yuki's DNA was grey wolf!

With that, everything started to make much more sense. It was no wonder his original owner couldn't handle Yuki — he wasn't a dog at all! Although pure wolves are known to be anti-social to humans, wolfdogs like Yuki are unpredictable. Whether or not he could be domesticated was unclear...

The staff at the sanctuary were hopeful that knowing Yuki's DNA would make it easier to domesticate him. After all, some wolfdogs can be successfully managed in a home...but it's a very low percentage. And with Yuki's injury and aversion to males, Shy Wolf Sanctuary became a permanent home for Yuki.

Growing up into an adult, Yuki weighed close to 120 pounds. He grew to be over five feet long, and by that time, the staff were grateful that Yuki was there to stay. After all, just because Yuki couldn't be fully domesticated didn't mean he couldn't have a family.

And thanks to the staff members at Shy Wolf Sanctuary, Yuki had his own fans, too! Through Instagram, the volunteers kept their followers up to date on the daily life of their very own wolfdog. They updated their followers on Yuki's favorite activities, and even on his love life.

Yuki went on to find a mate with a canine named Bella. To the shock of the staff, it was Bella who ended up being the alpha of the pair! The duo lived together happily for years, their lives broadcast on Instagram. But as Yuki got older, he received something no one expected: a cancer diagnosis.

Though heartbroken, Shy Wolf Sanctuary did their best to ensure that Yuki enjoyed his final days. In November 2020, after years of rescue, rehabilitation, and love, Yuki passed away. Though he would no longer roam the sanctuary, Yuki still managed to inspire Kent and Nancy into making a huge decision.

Inspired by their difficult but rewarding years with Yuki, the Shy Wolf Sanctuary successfully managed to purchase another area in Florida. With more funding, the staff will only continue to grow their animal haven.

Reviving an endangered animal species is no easy task, and it’s rare for population levels to bounce back after years of decline. This is especially true in the case of the California Gray Wolf, whose numbers have dwindled to the low thousands. But with their numbers threatened, one wolf pack made a bold move to ensure their safety, giving officials way more than they bargained for.

Of course, nobody saw this coming. If you were hiking through a remote part of California a few years ago, you might have been warned about grizzly bears. But the chances of coming face to face with any other potentially dangerous animals, especially wolves, wasn't very likely...

In fact, coming across an actual wolf sounds fairly far fetched to a regular tourist or hiker. In the early 1920s, though, this was a different story. Back then, wolves prowled California’s remote forests and farms alike. 

Because of this, farmers and wolves were constantly at odds. Farmers often hunted wolves in hopes of avoiding a barnyard massacre. They couldn’t have known then the damage they were inflicting, and not just on the wolves.

In 1924, the very last gray wolf was killed. For the next 90 years, California didn’t have any wolves in an area that could support up to 500 of them. Unbeknownst to farmers, the species' absence shifted the balance of the ecosystems they used to inhabit. 

“Wolves keep [elk and deer] in check, which helps vegetation not get overeaten. That vegetation provides nesting habitat for migrating birds and building material for beavers, which create ponds for frogs and fish,” said biologist Amaroq Weiss. And this domino effect was not only noticed by biologists.

See, if something good came out of the mass wolf killings in the ‘20s, it’s that the negative effects alerted researchers nationwide to the dwindling population of gray wolves. So in 1975, the gray wolf received federal endangered species protections...but there weren’t any wolves left to protect.

That is, until 2011, when one lone gray wolf wandered into Siskiyou County from Oregon. Biologists were stunned by this sudden re-emergence. Without a pack to lead or to protect him, this endangered wolf had traveled into an entirely new state — and immediately became an icon.

Though biologists designated him OR-7, activists named him “Journey” in honor of his daring cross-state trek. A GPS collar tracked and recorded his personal hike...as well as his encounters with other animals.

According to his GPS collar, Journey found a mate — likely another migrated wolf — and added five pups to the state’s gray wolf population. He then migrated back to Oregon and fathered more pups. It seemed like those were the last wild wolf pups California would ever see.

It was believed that, as of 2015, the population of wild gray wolves in California was an alarmingly small number: seven. Since two of the seven wolves were wearing GPS collars, biologists thought that enough of the state’s wolves were being tracked...

So imagine the biologists’ shock when, in 2019, two adult wolves were seen caring for three young pups in California. Biologists had no idea these wolves were even there, let alone that they were having pups. Even more unexpected was the way biologists discovered the pack.

The pack was seen hunting and resting on a trail camera in a remote part of Lassen County. The three pups snacked on grass and howled at each other before passing through. Though it only lasts a minute, this footage created a huge stir in the environmental community.

“Having wolves return to California is one of the most significant environmental developments in conservation in this state,” Weiss asserted. This sounds like triumphant news for conservationists and activists everywhere, but some people are far from happy about the wolves’ return.

Farmers and hunters have always tried to subdue the wolf population in California in order to protect their valuable sheep and cattle, and this didn’t change when California’s Fish and Game Commission granted gray wolves special protection under the state’s Endangered Species Act in 2014.

Now that the population seems to be slowly ratcheting upwards, farmers are once again in fear of their livestock being hunted. When California’s Farm Bureau Federation took the matter to court, the fate of the wolves was put into jeopardy. 

Farmers weren’t the only group threatening California’s wolf population, either. The federal government, too, pushed to remove gray wolves from the endangered species list, meaning they would no longer benefit from federal protection. Everything, it seemed, would all come down to the lawsuit.

In the end, the consensus among the scientific community and the court was clear: no matter what happened at a federal level, California’s gray wolves would be protected under state law. In a perfect world, this would keep the gray wolves safe from hunters…

“If they’re coming from the Oregon side of the border or from Nevada, once they set a paw down in California they are protected,” Weiss said. But these idealistic words would not become a reality anytime soon.  

Late last year, a California-born wolf pack mysteriously vanished in remote Siskiyou County. Since biologists weren’t able to collar any pack members, they may never know what happened to the pack. What’s more, they’re not the only mystery to plague California’s Department of Fish and Wildlife.

They’re also investigating the death of a young wolf that was mysteriously killed in Modoc County. It was handled as a criminal investigation, and the police warned the public that killing a wolf is a potential crime punishable with imprisonment. 

These tragic events only make the recent pack sighting on the trail camera all the more inspiring. Despite the resistance from the farming community, biologists remain hopeful that the wolves will one day lead many wild packs across California and beyond. Of course, wolves' interactions with humans could leave them forever changed.

One study, conducted from DNA found in Siberia, suggests that there is at least 27,000 years between the modern dog and wolf. Despite similarities in their appearance, it's clear that, at some point, the evolutionary paths of both animals diverged. And while dogs still have wolf-like instincts, it wasn't known until recently how dog-like wolves really are.

Wolves actively fear humans, and they avoid territory occupied by them. They're also far more independent than their domesticated counterparts despite their pack-like mentality. For example, when wolf packs go hunting, the pups are often left alone to learn to take care of themselves.

Dorottya Ujfalussy, from Eötvös Loránd University in Hungary, was more interested in the similarities between the two animals, though. For example, both wolves and dogs like to greet each other by licking the other's faces. Similarly, both dogs and wolves can understand certain human gestures, like pointing fingers — something chimps actually struggle to understand!

Ujfalussy conduced a study that analyzed the characteristics exhibited in wolves that were raised by humans caregivers. Ten grey wolves pups participated, seven females and three males, all of which were raised by humans and lived in captive packs.

The pups started the program when they were only 4-6 days old and were assigned to a foster parent. They spent 22-24 hours a day in close contact with their caregiver and were socialized in a domestic way.

For the first four-to-six weeks, the pups were carried in pouches. Later, they were leash trained so they could be exposed to domestic social situations, like encountering human strangers, novel objects, and urban settings. They were also socialized with their litter mates several times per week.

After about one year of care, the wolves were assimilated back into a wolf pack environment. All the while, scientists made some remarkable observations and concluded there was one common dog-like trait observed in all their wolves.

The common trait? Wolves who associated nurture with a human exhibited a unique attachment to their specific caregiver. There was an evident level of trust and companionship prominent between the pair.

Royal Society Open Science published this research on June 27, 2017, which concluded not only did wolves express a connection to their human caregiver, but these feelings lasted through the animals' adulthood, even if they still retained their inherent sense of fear toward humans.

Such observations led researchers to believe the common ancestor of dogs and wolves may have actually been open to human companionship, leading to the evolution of the friendlier, cuddlier ancestor — the dog that we all know and love.

Upon further observation of the behavior between wolf and human, it was noted that when socializing, wolves approached a human similarly to the way they would approach a member of their pack. This would include contact seeking and submissive behavior.

Wolves approached their human caregiver with lowered-body posture with lowered ears and low wagging tail. They would also display face-to-face oriented licking, jumping, and pawing, usually followed by a leaning or rubbing/nudging motion on the human.

Kathryn Lord of University of Massachusetts Medical School stated, "this result is exciting, not because wolves are more social than we thought, but because it is a step in uncovering the complexities of the differences between dogs and wolves in how they interact with humans."

Learning the key differences between wolves and dogs can only help us further understand the ancestral lineage and evolutionary divergence that has lead to the wolf and dog species we know today.

Like any thorough scientific study, there were a number of other observations and conclusions made. Perhaps the most important one, though, was that as much as wolves have the capacity to connect with humans, they are not domesticated animals.

They are still wild by nature, and they still are an entirely different species than dogs, even if raised by humans. This means that people should not try and domesticate wild wolves or wolf pups!

"The problem starts when people disregard the advice of professionals and mistake wolves for dogs, keeping them as pets," Ujfalussy said. "This is a serious welfare issue for wolves, as 99 percent of those animals will eventually be given up and usually euthanized."

This is especially true when wolves are taken out of their natural habitats to live with humans. Moreover, studies of a dog's brain prove that they are truly happier around us — even more than when they're around other dogs! Humans reduce stress in dogs. Yet, that's not the case with wild wolves.

This research was quite groundbreaking. "What we learned from our study is that while dogs may be more attached to their human caretaker in the sense of dependence and using their owners as a secure base," Ujfalussy said , "wolves are also able to form lasting affiliative relationships with their caretakers, though without a sense of dependence."

Ujfalussy's final note was: "Basically, wolves are wild animals, more independent, hard to control, hard to manage, and health-keeping conditions are impossible to provide in the human home, thus tame wolves kept as pets are a real danger to their environment and to themselves."