The Cy-Fair Volunteer Fire Department says Bretagne (pronounced Britney) was a founding canine member of its search and rescue team in 2000.
She joined members of Texas Task Force 1 sent to the World Trade Center site in Lower Manhattan after the terrorist attack brought down the buildings on Sept. 11, 2001. She later responded to disasters like Hurricanes Katrina and Rita.
Bretagne was honored with an epic 16th birthday in New York City last year.
A statement from the Texas A&M Engineering Extension Service says Bretagne, a Golden Retriever, was euthanized Monday at a veterinary clinic in the Houston suburb of Cypress.
Even Texas Gov. Greg Abbott tonight thanked Bretagne for her service in a tweet.
The last living 9/11 rescue dog has passed away. Texas & America are forever grateful for Bretagne's servicehttps://t.co/w8uFJDiMuk— Gov. Greg Abbott (@GovAbbott) June 7, 2016
Bretagne was 2 when she and her handler, Denise Corliss, were part of the Texas Task Force 1. They spent 10 days at the scene searching rubble for human remains.
Bretagne retired from active duty at age 9.
The Associated Press contributed to this report.