The last known living 9/11 search dog has died in a Houston suburb at age 16.

Bretagne, a golden retriever, was euthanised Monday at a veterinary clinic in the Houston suburb of Cypress, according to a statement from the Texas A&M Engineering Extension Service.

Bretagne was two years old when she and her handler, Denise Corliss, were part of the Texas Task Force 1 sent to the World Trade Center site in Lower Manhattan after the terrorist attack brought down the buildings on September 11, 2001. They spent 10 days at the scene searching rubble for human remains.

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About two dozen first responders lined the sidewalk leading to the veterinarian’s office and saluted Bretagne as she walked by for the final time Monday, The Houston Chronicle reported. An American flag was draped over her body as she was carried out of the facility.

Bretagne retired from active duty at age 9. At 15, she was taken by Corliss to the 9/11 memorial and participated in an interview with Tom Brokaw of NBC News.

Corliss told NBC’s Today that in recent weeks Bretagne began experiencing kidney failure and slowing down.

Bretagne was nominated for a Hero Dog Award from the American Humane Association in 2014. An online biography posted by the organisation says Bretagne served as an ambassador for search and rescue dogs in retirement, often visiting elementary schools.

Bretagne and Corliss met with former President George HW Bush at his presidential library late last year.

A post on the Texas Task Force 1 Facebook page remembers “the valiant effort and dedication to finding a victim trapped in a destroyed building that Bretagne showed us on a regular basis”.

Bretagne returned to New York where she was given a hero’s welcome last year. Photo: Texas Task Force 1/Facebook