Tian Tian, the 20-year-old male giant panda at the Smithsonian's National Zoo, looked to be in pretty good shape on Wednesday afternoon as he chewed bamboo inside his pavilion. A medical checkup on Tuesday had dismissed concerns for his health.

"Nothing comes up," zoo biologist Laurie Thompson said on Wednesday of the checkup.

Tian Tian may be starting to show some changes that are normal for an older bear, the biggest being that he has lost weight over the past several months, the zoo said in a press release.

Tian Tian's weight has leveled off and been holding steady at 260 pounds for the past month, however. His behavior and appetite are normal, but the panda team wanted to take a closer look as an added precaution.

The preventative health exam for Tian Tian on Tuesday allowed the zoo's veterinarians to get an up-close and in-depth look at him while he was anesthetized.

As part of the exam, they took blood and urine samples and x-rays. They also performed an ultrasound to get a look at his internal organs.

"Veterinarians did not find anything abnormal," the zoo said in a press release on Wednesday.

During the exam, doctors also took the opportunity to perform acupuncture and laser treatment - the acupuncture may help improve some of Tian Tian's overall muscle tone, and the laser therapy may help what might be arthritis in his left shoulder.

On Wednesday afternoon, panda keepers were seen interacting with Tian Tian while he was playing in his outdoor yard.

Tian Tian is the father of the only three surviving giant panda cubs born at the National Zoo - Tai Shan and Bao Bao, who have both returned to China to join breeding programs there, and Bei Bei, who still resides at the zoo.

chenweihua@chinadailyusa.com