The first documented case of an animal being abused on film was also shown in the CBC documentary. Tospy the elephant was electrocuted to death on film, and the image will haunt me forever.

http://www.boingboing.net/2008/01/03/edison-electrocuted.html

Edison electrocuted an elephant 105 years ago today
Posted by Cory Doctorow, January 3, 2008 10:24 PM | permalink
Today's the anniversary of Thomas Edison's vicious electrocution of a live elephant in order to prove the dangers of Nikola Tesla's alternating current and the safety of his competing direct current.

When the day came, Topsy was restrained using a ship's hawser fastened on one end to a donkey engine and on the other to a post. Wooden sandals with copper electrodes were attached to her feet and a copper wire run to Edison's electric light plant, where his technicians awaited the go-ahead.
In order to make sure that Topsy emerged from this spectacle more than just singed and angry, she was fed cyanide-laced carrots moments before a 6,600-volt AC charge slammed through her body. Officials needn't have worried. Topsy was killed instantly and Edison, in his mind anyway, had proved his point.

A crowd put at 1,500 witnessed Topsy's execution, which was filmed by Edison and released later that year as Electrocuting an Elephant.

Link