NASHVILLE − Country music star Miranda Lambert, a well-known advocate for shelter dogs and animal welfare, confirmed she is mourning the loss of two of her cherished rescue dogs.

In two recent, separate Instagram posts, the 40-year-old singer, who lives with her husband on farm about an hour south of Nashville, revealed in that she’d lost Delta Dawn and Louise, "the best and most loyal friends I have ever had."

"I’m so heartbroken to have lost them," the awarded-winning "Bluebird" and "Mama's Broken Heart" singer wrote in her first social media post. "To love this big you have to hurt just as big. They are worth it."

Miranda Lambert's dog Delta Dawn

In the post, Lambert wrote she spent 16 years traveling the world with her Chihuahua and pug mix, Delta Dawn, before the dog's April 22 death. The post includes photos and videos of her late dog who she said she found at an Oklahoma Sonic Drive-In in 2009.

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“She was homeless and hungry but still full of personality. I opened my car door and she jumped in,” she wrote. “Little did I know when I was trying to just get a cherry limeade, I would meet one of the most amazing dogs I would ever know.”

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Miranda Lambert's dog Louise

In the second post created over the weekend, Lambert paid tribute to her late dog Louise, who she wrote went by the pet names Lou Lou , boo boo, Lou bell, Lunas, and fluff cloud.

"Yesterday we said goodbye to the fluffiest most protective gal pal I could ever ask for," wrote Lambert, who rescued Louise and her sister Thelma in 2016.

“The first day I ever brought them to the farm in TN they were right at home,” Lambert wrote. "I have mini horses, chickens and goats and I needed them for protection for the critters. And boy did they do the job. I had 7 years with Thelma who we lost last July and 8 years with this beauty. My Lou Lou polar bear. She loved it when I sang her ‘special songs’ to her.”

Both dogs, according to Lambert, passed away within the past six weeks.

Maranda Lambert's MuttNation non profit

In addition to being an empowering female country artist, Lambert and her mother Bev Lambert founded the MuttNation Foundation in 2009.

According to its website, the nonprofit has raised more than $9 million since inception and aims to promote shelter pet adoption and spaying and neutering pets.

"The goal is to ensure as many dogs as possible would have a safe place to call home," she previously told the USA TODAY Network.

The non-profit also works with transport partners to assist and relocate animals during natural disasters.

Natalie Neysa Alund is a senior reporter for USA TODAY. Reach her at [email protected] and follow her on X @nataliealund.