Maddox became the only visitor in the zoo's 116-year history to die when he unexpectedly lunged out of his mother's grasp, over the wooden railing, and into a net meant to catch falling debris and trash. He bounced from the net into the dogs' enclosure about 10 feet below.
The animals immediately attacked the boy, who bled to death from massive injuries.
The zoo's 20-page response takes issue with claims that the exhibit wasn't safe, noting the wooden plank at the top of the railing was slanted 45 degrees toward the viewing platform "in order to keep visitors, including children, from sitting or standing on the railing."
Mongeluzzi has argued in the lawsuit that zoo officials were told by at least two employees that parents routinely lifted children onto the railing and, therefore, should have taken even more precautions.
"Maddox Derkosh was fatally attacked and killed at the zoo, when the zoo, after being warned by their own employees of the very accident that would occur, summarily dismissed their warnings," Mongeluzzi said Thursday.
Zoo spokeswoman Tracy Gray declined to comment on lawsuit but said in a statement that the zoo has met safety standards of the Association of Zoos & Aquariums and that the U.S. Department of Agriculture found no problems with the exhibit in 35 inspections since 2006.
The dogs have been relocated to other zoos and the exhibit now houses cheetahs.