The elephants found dead this month were believed to be from the same family group and ranged in age from 4 to 20 years, said Sen Nathan, the wildlife department's senior veterinarian.

NPR: 10 Dead Borneo Pygmy Elephants Feared Poisoned

"Antibiotic use in animals is out of hand, " said Dr. Gail Hansen, a veterinarian and senior officer for the Pew Campaign on Human Health and Industrial Farming, a project aimed at phasing out overuse of antibiotics in food production.

CNN: What government tests found in your meat