The horse in
Jesse James was killed by being ridden off a cliff into a river.
Taras Bulba amazes me too Mark. The old cinema cuts were made for a 'U', yet the footage removed was mostly dummy horsefalls. The violence (mild by today's standards) was left intact.
Michael York's horse is tripped by roadside bandits in
The Four Musketeers (similar to the Donald Pleasence scene cut from
Soldier Blue) though somehow the BBFC missed it (amongst other things). Faye Dunaway's horse is also tripped in a similar fashion.