It's tough getting old, and that goes as much for giant pandas as people.

Veterinarians at the National Zoo in Washington, D.C., say Tian Tian, an adult male panda, received laser treatment and acupuncture for what they initially thought was a touch of arthritis in his left shoulder.

During the exam earlier this week while the 20-year-old Tian Tian (pronounced t-YEN t-YEN) was under anesthesia, vets also took blood and urine samples and performed X-rays.

"Veterinarians did not find anything abnormal, but Tian Tian may be starting to show some changes that are normal for an older bear," according to the zoo's website. "The biggest change that the keepers have noticed is that he has lost some weight during the past several months. He weighs 260 pounds, and his weight has been holding steady for the past month. His behavior and appetite are normal, but the panda team wanted to take a closer look as an extra precaution."

Veterinarians said they also took the opportunity while Tian Tian was under "to perform acupuncture and laser treatment — both are complementary treatments. The acupuncture may help improve some of Tian Tian's overall muscle tone, and the laser treatment may help suspected arthritis in his left shoulder."

Chief veterinarian Don Neiffer told CBS that he used to think acupuncture was "all a bunch of hooey," but not anymore, because he's seen it work.

Neiffer tells CBS news that Tuesday's exam determined that Tian Tian's shoulder soreness was not the result of arthritis after all. As for the weight loss, they have yet to diagnose a cause.

The panda was born in China and is the half-brother of Bai Yun, who lives in San Diego — at the zoo there, that is.

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