Maddox Derkosh was fatally mauled on Nov. 4, 2012 at the zoo's now-closed African wild dogs exhibit when he was lifted by his mother above a railing to get a better view, lurched forward and fell.
Parents Jason and Elizabeth Derkosh filed a lawsuit in May that accuses the zoo and the Zoological Society of Pittsburgh of wrongful death and negligence and seeks a minimum of $300,000 in damages.
In its response, filed earlier this week, the zoo denied claims that officials had ample warning that parents lifted their children onto a railing by an unprotected area overlooking the exhibit, and said the child's death was due to Elizabeth Derkosh's "negligence and/or recklessness."
Attorneys for the zoo said Derkosh placed her son over the top of the railing and failed to "maintain a proper grasp" of him - claims the family's attorney Robert Mongeluzzi dismissed.
"Their answer blaming the Derkoshes is outrageous," attorney Robert Mongeluzzi said on Thursday. "Maddox Derkosh was attacked and killed at Pittsburgh Zoo and now the zoo is attacking what's left of the family."
The zoo also said that the railing surrounding the enclosure was at least 42 inches high and complied with all applicable building and safety codes. It also denied claims made by the family that it had "out-of-date, non-functioning tranquilizer darts" before the accident.
The court battle is continuing.