They say a dog is a man's best friend, but in this case, it's clear he's a little boy's best pal.

Paula Williams from Lubbock, Texas, tugged at the heartstrings of millions when she posted a video of her son Kahne, 6, reuniting with his dog who was missing for a month. The happy mom shared the emotional moment on the city's Lost and Found Pets Facebook page.

"On Dec. 4 our dog Kase went missing," Williams told TODAY.com about the heartbreaking day. "We let him outside to go to the bathroom and when we went to let him in he was gone. My son cried and we went searching up and down the street, but couldn't find him."

To make matters worse, a week after he went missing the area suffered a huge blizzard with close to 20 inches of snow, and the family didn't know the fate of their beloved pet.

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Over a month later on Jan. 8, Williams said she was coming home from dropping her son off at his grandmother's when she got stuck behind a school bus. "I saw two little girls get off and then saw Kase run up to them. So I pulled in and said, 'That's my son's dog.'

Paula Williams with her son and Kahne snuggling with Kase at home Paula Williams / Courtesy of Paula Williams

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"The family said that the dog had come to their house, so they took him in, fed him and gave him a warm place to say," she said. "If they wouldn't have taken him in we don’t know what would have happened."

What followed was the tear-jerking moment — captured by Williams on her phone — showing the 6-year-old sobbing with joy after reuniting with his beloved pet. "I missed you," says Kahne as he hugs his furry friend. The dog seems just as excited, licking his young owner on the face.

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"We've had pets since my son was born and he has grown up with them, but he's never bonded with an animal like has with Kase," said Williams. "I had to stop myself from crying in that moment. This was his dog. My son picked him out from the litter and from that day on he said that was his puppy."

Kahne holding his best friend Paula Williams

The video has since received nearly 4 million views, and has been shared more than 67,000 times, collecting more than 8,500 comments.

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"Oh my gosh! I'm crying with him. I'm so happy you found Kase. I know your son must have felt so awful without his buddy," one user wrote. "How beautiful and moving," wrote another. "That is proof how much love an animal has. He was trying to comfort that little boy. If he had arms I bet that would have been one of the biggest hugs ever!"

Williams is surprised by all of the attention. "It's crazy," she said. "I had posted on the Facebook page that Kase had been missing several time. So, when we were reunited I just wanted to share a good story and give hope to people that have pets who are still missing."

Even the administrator of the Facebook page, Ryan Mayfield, told us he's "blown away" by the response the video has received. "The page was just started as a way to help local families reunite with their animals," he said. "It's like a digital version of a missing sign you'd post around town. And this video is just one of the thousands of reunions we've seen come about because of the page and it proves that getting the word out can really help."

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Since the happy reunion Williams says Kahne does not let Kase out of his sight, and that Kase will not leave his side. "They sleep together," she said. "They are constantly together."

Kahne sleeping with his beloved Kase Paula Williams

With this newfound fame, Williams and the city's Lost and Found hope this touching story gives hope to families with missing pets and inspires other cities to create similar pages. "It will make a huge difference and increase the chances for more reunions like this," said Mayfield.

"The reason that I posted the video was to give people hope," said Williams. "It may be two years or two weeks, but there's still a chance you'll find your pet."