Philadelphia Eagles quarterback Michael Vick’s appearance at several book-signing events over the next week have been canceled because of threats of violence received by the organizers.

Philly Mag’s Tim McManus reported (via Pro Football Talk) that the publisher of Vick’s autobiography shut down planned appearances in Atlanta, New Jersey and Pennsylvania because of the threats. Vick had been set to sign copies of his book, Michael Vick: Finally Free, at three Barnes and Noble stores.

According to the report, the threats stem from reaction to Vick’s involvement in a dog-fighting ring, which have intensified since Vick acknowledged last fall he was once again a dog owner.