A stock horse is a specific type of equine mammal that is considered especially suited to working with livestock — cattle in particular. They tend to be characterized by their agility, quickness and intelligence. Most stock horses have a muscular build with powerful hindquarters.
The quintessential example of a stock horse might be the type of horse ridden by the cowboys of the western United States. Other places with large open spaces and a history of cattle husbandry, such as portions of South America and Australia, have also made extensive use of these horses. Like most working animals, a stock horse comes from a long line of ancestors that have been domesticated by humans to perform certain tasks. Arabians, quarter horses, quarabs, mustangs, appaloosa and morabs are common examples of stock horses, although any horse that is used for working with livestock, or any horse that is trained to participate in competitions requiring interaction with livestock, would qualify as a stock horse.
Along with their powerful physical appearance, stock horse breeds are also judged by their cow sense. "Cow sense" is a term used by people who work with stock horses to refer to the horse’s innate ability to interact with and control livestock, especially cattle. Horses with this ability tend to be laid back but observant, and they have an instinctual knack for making cows move in the desired direction. These traits might be the result of selective breeding over many successive generations, but a good stock horse will also be trained to complement its inherited traits. There are various organizations around the world that hold many shows and competitions in which stock horses can be judged.
For competition purposes, it typically takes between 18 months and two years of training for a stock horse to be ready for a competition. Some categories of competition include campdrafting, cutting, reining and team penning. These categories are generally based upon the movements required of a working ranch horse. For example, "cutting" is a term that is derived from the practice of separating a herd of cattle into different groups for different purposes, such as one group to be branded and another to be shipped to market. The cutting horse would enter the larger herd and separate an individual animal from the group so that it could be herded to the group to which it belonged, and in a cutting competition, a stock horse is judged on how well it makes the types of movements that would be required if it was completing such a task on a ranch.