USS Nimitz’s beloved working dog dies, leaves behind legacy of comfort and companionship

A four-legged shipmate who lifted spirits aboard the USS Nimitz leaves behind a legacy that touched the hearts and minds of crew members across the Navy’s oldest aircraft carrier.

“He never met a stranger. Everybody was his best friend,” said Brooke Corson, director at the nonprofit Mutts With A Mission.

Capt. Poseidon, a black Labrador retriever, died unexpectedly after experiencing a medical emergency that ultimately led to his euthanasia, Mutts With A Mission announced Monday in an Instagram post.

“A Mutts With A Mission staff member was with him as his suffering was ended and he passed on to his next great mission,” the organization said in the post. The organization did not disclose the date of death or the details of the medical condition. Poseidon was 3 years old.

With most crew members still on post-deployment leave, the command is planning a memorial ceremony for Poseidon after the crew returns, tentatively scheduled for early September, said Lt. Cmdr. Peter Pagano, Nimitz’s public affairs officer.

“The entire Nimitz team is grieving the loss of our beloved shipmate, Capt. Poseidon, who, over the past two years, provided all of us with the resiliency, comfort and compassion we needed to complete the mission at hand. We will never forget his profound impact in service to our ship, our Navy and our nation,” Pagano said.  

Nimitz facility dog, Poseidon, a “Mutts on a Mission” dog, rejoins the crew of aircraft carrier USS Nimitz in San Diego, March 12, 2026. (Julian Jaime/U.S. Navy)

Nimitz facility dog, Poseidon, a “Mutts on a Mission” dog, boosts morale of Sailors during flight deck PT on the flight deck of aircraft carrier USS Nimitz in the Pacific Ocean, April 15, 2026. (Tanner Orth/U.S. Navy)

Poseidon was one of several expeditionary facility dogs provided by Mutts With A Mission to support sailors and Marines during deployments. He was the first expeditionary facility dog to serve aboard Nimitz, Corson said.

“He made deployments a little easier for everybody,” Corson said, adding that Poseidon brought a “piece of home” to the crew and enabled people to reach out for mental health services.

Expeditionary facility dogs are specially trained dogs that serve aboard U.S. Navy ships. They work with entire crews, helping sailors and Marines reduce stress. And they boost morale on board.

“(Poseidon) was a dog who made everybody feel like they were the most important person in the world when he was visiting with them,” Corson said.

There are five other dogs stationed across the Navy fleet: Cmdr. Ike on USS Wasp; Capt. Sage on USS Gerald R. Ford; Capt. Rudder on USS Carl Vinson; Capt. Fathom on USS Abraham Lincoln; and Capt. Demo with Strategic Communications Wing 1 at Tinker Air Force Base, Okla.

Trinidad and Tobago government and military leaders pose for a photo “Mutts on a Mission” facility dog, Poseidon, and Nimitz-class aircraft carrier USS Nimitz Handler, Lt. Cmdr. Louis Martinez, in the flight deck control room during a distinguished visitor tour in the Atlantic Ocean, May 25, 2026. (Molly Guy/U.S. Navy)

Poseidon, a “Mutts on a Mission” dog, visits the main media shop aboard the aircraft carrier USS Nimitz in the Philippine Sea, April 30, 2025. (Franklyn M. Guage/U.S. Navy)

After completing two years of training with his puppy raiser family, Poseidon began serving aboard the Nimitz in March 2025 and completed two deployments with the ship.

Poseidon’s death comes nearly three weeks after the Nimitz arrived at its new homeport in Naval Station Norfolk, Va. The beloved Labrador at the time was greeted on the pier by fellow furry friends as he returned with the crew from what was likely the carrier’s final deployment.

“We were gonna let him work with (USS Nimitz) a little longer, and then we had another assignment for him,” Corson said.

The carrier left previous homeport, Naval Base Kitsap, in Washington on March 7 and circumnavigated South America, hosted multinational exercises and made a stop near New York City for the 250th anniversary of the United States.