Definition of "shabrack"

Oudet and Papilette, two of the best sub-officers in the regiment, were at their head. When I had them formed up in fours, all in silver grey and upon chestnut horses, with their leopard skin shabracks and their little red panaches, my heart beat high at the sight.

1896, Arthur Conan Doyle, The Exploits of Brigadier Gerard‎