EXCLUSIVE

Alex Trebek^[1]'s dog runs after a pedestrian who falls into the street. What is Alex Trebek is getting sued. 

Hanna Ketai claims she was walking her yellow lab down an L.A. street earlier this month when a "large black dog" -- from Trebek's property -- came running at her and tried to attack her. The docs -- obtained by TMZ -- claim Ketai screamed, turned away and fell on her hands and knees into the street.

Ketai claims a large SUV was headed in her direction, but a witness helped her away from oncoming traffic and to safety.

As a result of the incident, Ketai claims to have suffered physical, mental and emotional pain, worry and anxiety. She also says it has affected her work abilities.

We reached out to a rep for Alex ... so far, no word back.

References^ Alex Trebek (www.tmz.com)

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