[redgolum]

Hitting a tiger with a dart will make him mad. The drugs won’t take effect fast enough to stop that tiger from attacking.

People have been killed trying to do so. The sheriff tried it, but even the people from the zoo said it was to risky.

[xsrdx]

One or two animals, I can buy the dart gun argument, if the animals aren't an immediate threat.

You couldn't dart 35 big cats successfully in a populated area without taking enormous risk.