Calgary Zoo officials say 2-year-old male Siberian tiger Vitale did nothing wrong when he got a hold of an intruder who had scaled two fences into zoo property overnight.
Police say the man was one of two who broke into the facility by scaling an 8 foot fence equipped with barbed wire at the north end.
He then breached a four foot fence outside the tiger main enclosure.
It's believed the 27-year-old approached the exhibit and was hooked by the animal's claw.
A spokesperson for the zoo says the tiger has never been in this kind of situation before and reacted naturally as a carnivore.
The zoo says it's reviewing security procedures but notes if someone is eager enough to break into a property, they'll find a way to do it.
"You have to rely on people to use common sense," said zoo director Graham Newton.
Police said the man's arm injuries were so bad he may lose the limb.
Zoo officials also add a second man who broke into the property was an acquaintance of a security guard but there's no evidence to suggest security staff had anything to do with what happened.
Motive for the break-in is under investigation.