Miranda Lambert is mourning the loss of a good friend. The singer shared on Thursday evening (Oct. 22) that her dog, Waylon, has died, also telling the story of how he came to be hers in a heartfelt tribute post on social media.

Lambert says she discovered two stray puppies on an Oklahoma roadside in 2008, "starving and freezing nearly to death."

"I was listening to Jessi Colter and Waylon Jennings at the time me and mom saw them and pulled over to pick them up," the singer recalls. She took both dogs to the vet, who told her that the male probably wouldn't survive.

"But he did. For almost 13 years," Lambert continues. "He was a rock in our family and always held down the fort."

The "Bluebird" singer indicates that the other dog, Waylon's sister, Jessi, is still living, and how happy she is that her husband of nearly two years, Brendan McLoughlin, was able to get to know Waylon before he died.

"We are heartbroken but happy that he is running across the rainbow bridge right now and will be waiting for us when we get there," says Lambert, a known dog lover who has taken in many strays over the years. "Dogs change your life. The bond is something that can’t be described unless you have lived it."

Lambert is one of country music's most famous animal lovers, even taking her fostering and adoption efforts to a new level with her MuttNation Foundation. The year after she found and adopted Waylon and Jessi, the singer and her mother Bev founded the non-profit organization to help shelter animals across the country

On Wednesday, the country superstar released a new music video for her song "Settling Down" that shows her home life: writing songs, laying on the hammock, fishing and spending time with McLoughlin and their pets. Another of her rescue dogs, Delta Dawn, makes a cameo.