The last surviving search dog who helped to find survivors after the Twin Towers came crashing down on September 11 has died.

Bretagne, a 16-year-old golden retriever, was euthanized on Monday in a Texas veterinary hospital.

With a host of honors to her name and countless searches behind her, Bretagne was honored - as any human would be - one final time before her death.

A row of firefighters stood at attention as Bretagne walked with her owner, Denise Corliss, into the Fairfield Animal Hospital in Cypress, Texas.

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Respect: Bretagne, a 16-year-old golden retriever who was part of the search team during 9/11, was euthanized on Monday in a Texas veterinary hospital

Salute: A row of firefighters stood at attention as Bretagne walked with her owner, Denise Corliss, into the Fairfield Animal Hospital

Final goodbye: With a host of honors to her name and countless searches behind her, Bretagne was honored as any human would be

Bretagne began suffering from kidney failure and when she stopped eating, Corliss knew it was time to say goodbye.

'She was really anxious last night and she just wanted to be with me.

'So I laid down with her, right next to her. When she could feel me, she could settle down and go to sleep. I slept with her like that all night,' Corliss told TODAY.

Leading up to her death, Corliss and her husband wrote out a bucket list for Bretagne and completed the items on it before Monday.

One of them included visiting local Robert Road Elementary School where the pooch had become a story time pal and had also helped work with autistic children.

The dog was also a volunteer firefighter and - in addition to 9/11 - had aided in searches during Hurricane Katrina, Hurricane Ivan and Hurricane Rita.

'She had lived longer and accomplished more than anybody,' Cy-Fair Volunteer Fire Department spokesman Capt. David Padovan told the New York Daily News.

Thank you: Corliss said that at first, the scale of the disaster overwhelmed her, but Bretagne just looked eager to work

Taking a nap: Worn out and taking a breather

Deserved rest: Bretagne began suffering from kidney failure and when she stopped eating, which indicated it was time to say goodbye

Following her death, Bretange's body was draped in an American flag and driven to Texas A&M University.

There veterinarians will study the effect of Ground Zero on her body. .

'She was one of a kind,' Padovan added. 'She was always eager to do searchers, even after she "retired",' Padovan said.

Corliss bought Bretagne in 1999 after she was asked to take part in a training exercise for search and rescue dogs.

She said workers buried her underneath rubble for an hour before sending the dogs to find her, and she will always remember the relief she felt when she heard one of them barking above her.

After that, she decided to buy Bretagne and began training her to do the job. Within a couple of years they were deemed good enough to be assigned to Texas Task Force 1.

Fateful day: Bretagne was among the first 300 dogs to respond to Ground Zero in Manhattan following the terrorist attack

Support: She and her owner Denise Corliss (pictured) worked 12 hour shifts digging through rubble, sometimes sleeping for as few as 4 hours

At 13 Bretagne's joints began to stiffen and she could no longer climb the stairs in her home.

Corliss installed a pool and the two swam for ten minutes every day.

She said it made a world of difference and allowed the dog to regain flexibility in her limbs.

Bretagne celebrated her birthday last year in New York City, where she began her search career at two years old, searching through the rubble of 9/11.

She was one of 300 first responder search dogs who heroically braved the site of the largest terrorist attack on American soil.

During her 16th birthday celebration last year Bretagne and Corliss were treated to a hero's welcome at LaGuardia Airport in New York, before being taken to 1 Hotel Central Park courtesy of BarkPost.

Tired: The 9/11 mission was Bretagne's first deployment, but Corliss said she took to it perfectly despite the exhausting hours

Heroic: Bretagne worked tirelessly throughout the aftermath of 9/11 to try and rescue those hurt in the terror attack

There, Bretagne was given treats and a birthday cake to help her celebrate her 16th birthday, before the pair made their way back to Ground zero.

Corliss explained how she and Bretagne were sent on their first-ever search from the Texas Task Force to relieve the first responders at the World Trade Center.

The mission was Bretagne's first deployment, but Corliss said she took to it perfectly, despite working 12 hours days in some of the most difficult conditions imaginable.

For the birthday girl: During her 16th birthday celebration last year Bretagne and Corliss were treated to a hero's welcome at LaGuardia Airport in New York before having cake

Tasty: They also got to stay in the luxurious 1 Hotel Central Park courtesy of BarkPost and tour Ground Zero, where they had helped in the search efforts so many years earlier

A very sad day for the men & women with the Cy Fair FD. Today they said good bye to Bretagne (pronounced "Brittany") she's the last known surviving 9/11 search and rescue dog. She would have turned 17 in Aug. This video shows her walking into the vet's office one last time - getting a hero's salute. She was put down at 5pm. STORY-->http://bit.ly/1XB5dhM Posted by Jennifer Bauer on Monday, 6 June 2016

THE HERO DOGS OF SEPTEMBER 11 During the chaos of the 9/11 attacks, where almost 3,000 people died, hundreds of loyal search and rescue dogs and their brave owners scoured Ground Zero for survivors. Some estimate there were 300 dogs - others say 900. It is unknown exatly how many dogs in total searched the rubble of 9/11. In 2011 a book called 'Retrieved' documented the last living dogs of September 11. Most of the search and rescue dogs were Labradors or golden retrievers. A study of the dogs after the search revealed that no only did the dogs fair well, but they also helped prevent Post-Traumatic Stress Disorder in their handlers. It was revealed many of the dogs suffered cancer, however it was not inconsistent with the type of disease an elderly dog would typically encounter. The study also found the dogs lived a long time - a median 12 years. Source: Dogtime.com Advertisement

Corliss said that at first, the scale of the disaster overwhelmed her, but Bretagne just looked eager to work, and so helped her get on with what needed to be done.

Cindy Otto, a vet who works for Penn Vet Working Dog Center and cared for more than 100 dogs who worked at Ground Zero and tracked their health after, said:

'You'd see firefighters sitting there, unanimated, stone-faced, no emotion, and then they'd see a dog and break out into a smile.

'Those dogs brought the power of hope. They removed the gloom for just an instant.

'Bretagne's partnership with Denise Corliss was magical.'

But Bretagne's legacy will live on, not just through Corliss, but through another dog bearing her name.

Penn Vet Working Dog Center not only tracked the dogs of 9/11 but also trained new sniffer dogs who can find, people, drugs or disease.

A puppy named for Bretange - Bretange 2 - whon lives with a man who has Type 1 diabetes.