The Castillon (also 'Castillonais', 'Saint-gironnais', 'Ariegeois de Castillon', and 'Cheval du Biros') is a French light draft breed which originated in the Pyrenees. It should not be confused with the Merens.

A local horse:
Contrary to the famous Merens and Pottok that also originated in the French side of the Pyrenees, the Castillon was never a widespread or a well-known breed. There are no records of how it was 'developed', although it probably involved crossing the local horses, who roamed in the Pyrenees for thousands of years, with Oriental and Spanish breeds at some point or another.

The Castillon was always an all-around breed that was locally used for farming, pulling carts, and for cavalry. During the 20th century, the Castillon's already fragile population nearly went extinct due to excessive crossbreeding with heavy draft breeds and, later on, due to the mechanization of agriculture and transportation which rendered the Castillon obsolete.

During the 1980s, when only several dozens of pure Castillons were left, a small group of breeders teamed together to save the breed. In 1992 they established an official breeding association for the breeding and promotion of the Castillon. Furthermore, thanks to their efforts, the Castillon was officially recognized by the French authorities in 1996.

The Castillon today:
Today, the Castillon remains a somewhat obscure breed outside of the Pyrenees. Nevertheless, he is known locally as a good all-around horse, and is used for various disciplines, among them are recreational driving and riding, including trekking and recreational show-jumping.

Conformation:
The conformation of the Castillon is characterized by a large head with a concave-to-straight profile, short ears, a neck of medium length that connects to somewhat protruding withers, an extremely low-set tail, solid legs, and large hooves.

The hair of the mane and tail is often wavy, with the tail growing thick and long, and the mane being anywhere from short and sparse to long and full. The legs have light feathering.

Performance metrics:
The following are the: range, average, (SD), and MOE of performance metrics of ordered Castillons in Horse Isle (not bred ones). In rare cases, horses might have metrics outside of the range. Breeders can produce horses that are beyond this range.

Speed: 14.1-15.8, 15 (0.3), 0.06.
Sprint: 37-49, 43 (3), 0.59.

Accel: 0.74-0.9, 0.83 (0.04), 0.01.
Decel: 1-1.13, 1.06 (0.03), 0.01.

Jump: 4.97-5.24, 5.1 (0.06), 0.01.
Pull: 2.5-3.22, 2.81 (0.16), 0.03.

Turning: 43.74-56.68, 49.86 (3.06), 0.6.
Reverse: 2.2-2.8, 2.5 (0.1), 0.03.

Stamina: 46.64-51.48, 49.11 (1.09), 0.21.
Reaction: 0.74-0.85, 0.80 (0.02), 0.00.

Coats & Height:
Colors: usually seal-brown, less often black or 'bay' brown (the latter termed 'brown' in Horse Isle).
Additionals: sooty is extremely common.

Markings: The coat lacks white markings.

While Castillons are eligible for registration even if they have minor white markings on their legs, the breed standard still prefers that the hooves will be dark. In addition,
Castillons don't have prominent facial markings.

Therefore, in Horse Isle, Castillons don't naturally come with markings, and those who are born with prominent markings will receive a 100% penalty.

Height: 13.1hh to 15hh.