A woman has learned the heartbreaking reason why her rescue dog might be struggling to mix with other canines, and she told Newsweek the sad truth behind his inability to socialize.

Back in March of this year, Yaprak Yalcinkaya was thinking of getting a cocker spaniel puppy from a breeder when a bit of divine intervention struck.

"My boyfriend was driving one day when he saw a truck full of dogs," she told Newsweek. The truck belonged to Balkan Underdogs, a cat and dog rehoming initiative and registered charity primarily focused on rehoming dogs from the Balkans.

"So I scrolled on a charity's website called Balkan Underdogs and Runi was the first dog I clicked on," Yalcinkaya said. "He was found in a field full of sheep in Serbia. They think he was abandoned in the summer of 2022 when he was just six months old."

It had taken Runi a couple of months to get used to life in the shelter and trust his new carers. Not much is known about his life before but he carried one significant injury from whatever had come before: he didn't have a tail.

"They think he either had been in a fight with another dog or apparently sometimes their mothers dock it," said Yalcinkaya, from Sheffield, in the U.K. "He has a little nub that he wiggles when he is really happy but usually it's impossible to spot."

Working dogs often have their tails docked over concerns about potential injuries. However, data from the American Veterinary Medical Association undermines this with a major study on the topic finding just 0.23 percent of working dogs with tails suffered injury to this appendage.

Runi's lack of a tail was never a major concern for Yalcinkaya. "The funny thing is we didn't realize he didn't have a tail till very late in the adoption process," she said. "I don't think it would have changed anything at all but I fell for his cute face and ears anyway."

Whatever happened has clearly had an impact on Runi though. "They use it to balance themselves, and his balancing skills are zero to none," Yalcinkaya said. "We think he lost it in a fight because he is really scared of everything! He was scared of his own shadow when he arrived."

Runi is a happy dog in many respects. "Some of his favorite things to do is lick our legs as a form of begging whilst we eat dinner. He loves sniffing cars and he spends a good amount of time grooming Coco, his plush dog toy," Yalcinkaya said.

"He loves to destroy anything cardboard and follows me around the house. Sometimes he'll even pick up a dirty sock of ours and drop it in front of us."

But one thing Runi really struggles with is other dogs.

"He is quite reactive to other dogs mainly because I think the trauma he had to his tail," Yalcinkaya said. It was during a recent discussion with Runi's trainer that Yalcinkaya learned the "sad truth" about why her rescue dog struggles with other canines.

"Tails are usually the first indicator of emotions for dogs," she said. "When a dog sees a dog from a mile away they can understand if they are stressed or happy from tail wagging. But since Runi's is missing, his communication is a lot harder, the dogs can't read him and his emotions."

The result is that Runi has struggled to make many fellow dog friends.

"A lot of dogs snap or growl at him, they think he is weird," Yalcinkaya said. "Dogs with docked tails are more likely to have aggressive encounters and also because he is a black dog and dogs' sight isn't the best, they can't read them well either!"

Despite his difficulties with other dogs, Runi is well looked after. He lives in an apartment with a garden and Yalcinkaya works from home, meaning they get to spend lots of quality time together. Maybe one day Runi will find a four-legged friend who understands him but right now he's just happy having a human one that does.