The Chattanooga Zoo has had cause for celebration and sorrow this week. The exciting arrival of two cougar cubs was dampened by the death of their 4-month-old snow leopard cub, Everest.

Zoo staff found Everest dead in his enclosure Wednesday morning, according to a news release.

Staff believe Everest's death was a fluke.

"Everest exhibited no signs of illness and passed his physical last Tuesday with flying colors," Marisa Ogles, director of marketing and communications, said in a statement.

He was taken to the University of Tennessee School of Veterinary Medicine for a gross necropsy to determine the cause of his death. Early findings revealed a large, probably congenital tumor in Everest's heart, which caused an acute cardiac arrest.

But even as they mourn the loss of Everest, zoo staffers are looking forward to caring for their two new charges.

Two cougar cubs arrived at the zoo Tuesday morning.

The pair was discovered, orphaned and emaciated, in a Montana chicken coop by the Montana Fish, Wildlife and Park Service. They were handed over to the Oregon Zoo, which cared for them until they could be taken to their new home in Chattanooga.

"All of us at the Chattanooga Zoo are simply thrilled to have these two precious cougar cubs here at our zoo," said Darde Long, the zoo's executive director, in a news release.