The City of San Antonio Animal Care Services shared the heartwarming story on Facebook, explaining that the dog - named Samson - went missing 10 years ago.
Understandably, this 'broke his family's hearts', but despite doing everything they could to track him down, he seemed to be lost forever.
Fast-forward to 2021, when the poor dog was brought into the shelter in a pretty bad way.
Before he received treatment, Samson was scanned for a microchip, in turn revealing his owner - who was 'shocked' by the news and immediately rushed over to see his dog.
The man, known only as 'Mr. C', was worried that his pet wouldn't recognise him after all these years, but eventually the two enjoyed a tearful reunion.
The City of San Antonio Animal Care Services wrote: "'I wonder if he will still remember me?'
"This is the thought that ran through Mr. C's head as he waited to see Samson for the first time in 10 years.
"You see, Samson went missing a decade ago and it broke his family's hearts. They did everything they could to find him but never did. Still, they never forgot him.
"We brought Samson into our care last month along with six other abandoned dogs he had been with. He was in pretty rough shape, dirty and covered in fleas.
"Before he was able to get treatment, he was scanned for a microchip - and we found one! Mr. C was shocked to hear that Samson had been found, and rushed over to ACS."
The post continued: "He was so anxious to see his dear Samson after so many years but finally, it was time for the long awaited reunion. Mr. C kneeled down and said softly, 'Samson, it's me. Do you remember me?'
"Samson gently and slowly walked up to him and sniffed his hand. We could tell Mr. C was holding back tears as he said, 'They took the better years from us.'"
Staff also warned about the importance of micro-chipping pets, adding: "We don't know what happened to Samson all of those years, but the power of microchips holds true.
"We are so grateful that they can be together now. We can never stress enough how important it is to microchip your pets and microchip licensing is the law here in San Antonio.
"Congratulations on your reunion, Mr. C and Samson! We hope you can make some beautiful new memories."
The post has since gone viral, racking up 7,800 likes, 4,700 shares and hundreds of comments.
One Facebooker commented: "Oh. My. Word. I don't know whether to be sad for all the time lost or happy that they found each other again."
Someone else said: "Oh man, this got me right in the feels!! I'm so happy that they were finally reunited!!"
A third added: "Samson is so fortunate to get to spend his twilight years with family that loves him and will care for him."
Featured Image Credit: City of San Antonio Animal Care Services