The zoo held a memorial service Saturday for the popular 2-year-old elephant named Mac, who was remembered in anecdotes tinged both by sadness and laughter.
"The entire Zoo staff is absolutely devastated. It's difficult to put into words and describe the attachment that has developed over the past two years. This is a terrible loss especially for the elephant keepers and veterinary medical staff who cared for Mac during his time with us," said Houston Zoo spokesman Brian Hill.
The people at the zoo weren't the only ones grieving Monday, reports CBS affiliate KHOU-TV. The gentle giants in the elephant exhibit were also missing Mac. Behind a fence and to the side, Mac's mother, Shanti, and his aunt, Methai, looked on.
"They'll grieve just like people will. They're incredibly intelligent animals," said Houston Zoo Director Rick Barongi. "They know he's gone now."
Elephant keepers at the zoo alerted veterinarians Sunday morning when they saw that Mac was exhibiting symptoms of the virus.
"It attacks the blood vessels, causing them to leak and makes the heart work harder to pump blood and essentially have cardiovascular failure," explained Dr. Joe Flanagan, Directory of Veterinary Services at the zoo.
The young elephant weighed 384 pounds when he was born in October 2006, making him the largest Asian elephant born in captivity at a U.S. zoo, said Deborah Cannon, president and CEO of the Houston Zoo.
Mac learned more than 30 behaviors before he turned 1, something previously unheard of in elephants, Cannon said.
But the beast's energy suddenly vanished Sunday as he became lethargic and lost his appetite, two symptoms of elephant herpesvirus.
Before getting sick, Mac was known for his sense of fun and mischief. Noble recalled buying Mac an inflatable punching bag.
"He would come back to it, whack it with his trunk and then tear off and go running crazy about the yard," she said.
Death from elephant herpesvirus is usually attributed to heart failure. It was first identified in 1995 by researchers at the Smithsonian National Zoo and Johns Hopkins School of Medicine.
There is no cure for herpesvirus in animals, and there is not yet a direct test to detect it in a healthy animal. Over the past 20 years, the Houston zoo has lost six other elephants to the herpesvirus.
Other zoos across the country in recent years have also lost elephants to herpesvirus, prompting some animal rights groups to attribute the disease to captivity.
But Cannon said elephants are at risk of contracting the disease both in captivity and in the wild. Breeding elephants in captivity, she said, is the only way to ensure the species doesn't become extinct and gives researchers opportunities to study the disease more.