The currently ubiquitous LEGO System horse figure design was introduced in 1984 in several Castle sets, superseding previous designs of brick-built horses.
The new horse was a prefabricated figure consisting of a solid main segment representing the horse's body and legs and movable segment encompassing the head and neck. The body features a recess in its back, measuring 1x2 studs in base area and 4 plates in height, which is usually occupied by a saddle piece and allows standard minifigures to mount or dismount the horse without the need to bend the figure's leg assembly. The recess could be filled with a 1x2 brick plus plate if a saddleless horse without rider was preferred. Many sets with horses include a saddle and/or filler pieces. The recess also allows for the attachment of a horse-drawn carriage using various hinge pieces.
The first horses came only in black and white and were initially an exclusive feature of the Castle theme.
The Brown Horse Edit
The first brown horse was in introduced in 1986. After several updates, a new variant was introduced in 2007. This version sports a black bridle with white/silver details and the usual black with a white dot eye print currently found on other horses. The rearing model was introduced several years later. It has no special mane print, and this horse features a grey saddle.
This creature appears to be the Horse, Moveable Legs with Black Bridle and White Blaze Pattern (minus the white blaze on the face). This piece can be found in many LEGO sets, including Stagecoach Escape.