After doctors gave Bella just three to six months left to live last year, Robert Kugler took his three-legged dog on one last road trip across the country.

Bella, a nine-year-old chocolate labrador, has lung cancer and her condition is terminal.

Mr Kugler, a Marine veteran from Nebraska, told CNN: “I just didn't want her to be gone one day when I came home.”

After heading to the Marine Corps Ball in Chicago in November, the pair continued across the US in his Toyota 4Runner.

They travelled across states including Detroit, Kentucky and Ohio, checking out the sunset, Niagara Falls, monuments, museums and the Adirondack Mountains in New York.

Along the way, they stayed with friends or camped in his car, documenting his travels on Twitter, Facebook and Instagram.

They are currently on the west coast of Florida. Mr Kugler is considering driving back to Nebraska to avoid the summer heat, which Bella struggles to cope with.

Mr Kugler also plans to visit Yellowstone and Yosemite National Parks.

“Continuing to move and see the country is a good excuse to spend time with my dog,” he said.

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Speaking about her death, he said: “Some days I'm completely prepared. I pictured her just swimming out to sea.