Found this on the Pathe catalogue site (http://filmographie.fondation- jeromeseydoux-pathe.com/1169-cheval-emballe). It gave me new respect for Louis J. Gasnier (of 'Reefer Madness' fame).
Cirque d'Hiver, Paris, from 3 to 01.09.1908 In its issue 69 of 01.02.1908 Phono-Ciné-Gazette under "The danger in Cinematograph" recounted that ... the employee who ran the car risked his life as the vehicle made a plume which we did not expect when it comes to full market! And The Moving Picture World of 09.04.1910 the announcement of the arrival of Louis J. Gasnier to the direction of Pathé studio Bound Brook was followed by a story about the shooting of packaged horse: Mr Gasnier is a man of great resource and HAS HAD Many trilling adventures in the manufacture of films. One notable instance of This Was DURING THE photographing of the classic film The Almost Runaway Horse how much Was Heard It Was as to how feasible to secure a horse with intelligence Such as this one Seemed to have. The secret of the matter lay in the fact That underneath the body of the wagon was a two-wheeled vehicle. There was attached a coffin with the ends knocked out. This Was Because Of its chosen interior padding. In this, Mr. Gasnier Took His position, facing downward, and Entirely dressed in black, with black gloves and a mask similar to Those used on the days of the Inquisition, over His face, and from here he drove the spirited cavalry horse by means of two steel wires of the ends of which were Fastened to bold sticks For Him In His Hands. The shafts of the wagon Were Fastened to the body by bands purpose steels In Spite of this arrangement Mr. Gasnier was nearly killed. Just after the scene which shows the car knocking down the scaffold, the steel bands broke and Mr. Gasnier, as the car pitched forward and turned a full somersault, Was So badly Injured That He Was unconscious for more than half an hour and fifteen Spent days in the hospital. The horse, at the time of this accident was really running away, and HAVING rid himself of the cart, dashed ahead, and finally ran Into the river. Mr. Gasnier's nerve is shown by the fact That After His release from the hospital he got back Into the vehicle repaired and finished the picture.