CHATTANOOGA, TN (WRCB) -- Everest, one of the Chattanooga Zoo's snow leopard cubs died Tuesday. The four-month old male cub, according to zoo officials, exhibited no signs of illness and passed his physical last week.

The discovery was taken as a "devastating and shocking blow to Everest's keepers and all of zoo staff," according to a news release from the zoo.  

Everest was immediately taken to the University of Tennessee School of Veterinary Medicine in Knoxville for a gross necropsy.

Preliminary necropsy findings showed a large, likely congenital tumor in Everest's heart which caused acute cardiac arrest.

Dr. Anthony Ashley, Chattanooga Zoo Veterinarian notes that "since Everest displayed no outward signs of low energy, getting winded easily or listlessness, there was no reason for Zoo staff to suspect heart trouble. Therefore, sedating the cub for an echocardiogram would have been an unnecessary and likely fatal procedure."