According to a report in the Scotsman newspaper, solicitor Ronnie Alexander was trying to calm the raging animal and herd it into an alleyway where it could be held.
The bull started to lash out as it passed the town's butchers shop and charged Alexander, who fell and struck his head on the kerb.
The paper reports that Alexander is in a serious but stable condition, suffering severe bruising to the brain, a fractured skull and bruising around the heart.
The bull was eventually caught by officers from Central Scotland Police and a team from Blair Drummond Safari Park two hours after it escaped.
It has been transported back to its farm in Clackmannanshire, where it will remain until the tranquilisers wear off and it can be taken back to the abbatoir for slaughter.