Sully, the service dog who symbolised devotion lying by former US president George H.W. Bush's flag-draped casket, has a new mission.

The 2-year-old yellow Labrador Retriever on Wednesday joined Walter Reed National Military Medical Centre's dog programme to help wounded veterans. Sully offered his paw as he was administered an oath streamed on Facebook to "support, comfort and cheer warriors and their families".

Sully received a new vest and is considered a Navy hospital corpsman second class. Sully's Instagram account posted he looks forward to continuing his mission "as my best friend wanted me to".

The service dog was named for retired airline pilot Chesley "Sully" Sullenberger III, who became famous for landing a damaged passenger jet on the Hudson River in 2009.

Sully served Bush for six months until the former president died in November.

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