Rabicano, also called white ticking, is a horse coat color characterized by limited roaning in a specific pattern: interspersed white hairs most dense and originating from the flank and the tailhead. Rabicano is distinct from true roan, which causes evenly-interspersed white hairs throughout the body, except the head and legs.
The word "rabicano" is of Spanish origin - rabo meaning "tail" and cano meaning "white" - thus, it described a horse with white hairs in its tail. This definition is consistent with the modern usage.
The word appears very early in epic poems in Italian literature: Argalia, a character in Orlando Innamorato (1495), rides a horse named "Rabicano". So too does Astolfo. In Italian, the term simply means "roan" and might therefore have been a descriptive name.
The characteristics most often associated with the rabicano pattern are white hairs at the tailhead and the flank, where the body of the horse is joined by the hindquarters. Like other patterns and colors, the expression of the rabicano trait varies. Most of the factors affecting these variations are unknown, however, it is known that horses with a chestnut or chestnut-based coat express white patterns such as rabicano more readily; that is, they tend to have more white. Minimal expression includes a few white hairs in those areas, and for that reason is often not mentioned in descriptions of an individual horse's color. Rabicano is a white pattern that falls into the category of roaning or scattered white hairs, the genetics of which are not yet fully understood.
The original definition of "rabicano" refers to the presence of white hairs in the base of the tail, a characteristic called a "skunk" or coon tail. The term "coon tail" is associated with white hairs in the form of striping at the tailhead. The sides of the tail at the tailhead may have much white hair. Extensively-marked rabicanos sometimes exhibit striations in their pattern on the ribs, giving them a striped appearance.
Prevalence and inheritance
The rabicano pattern is thought to be a dominant gene in some families, however other forms of white ticking not following the rabicano pattern may exist and be controlled by separate mechanisms. Rabicano is present even in breeds which do not possess any true roan individuals, such as Arabian horses. In the Arabian, Rabicano patterning is even defined as "roan." Rabicano may occur on any base color and may occur in conjunction with any other white pattern, including true roan or gray.
Higher expression of the rabicano pattern on the flanks may produce a coat easy to mistake for true roan. However, in highly-expressed rabicanos, the distribution of white hairs along the barrel may produce faint striping or stippling over the ribs, which is not seen in true roans. Furthermore, the skin of some rabicanos may be slightly mottled with pink, particularly on the abdomen and groin. This trait is not seen in true roans, and suggests that, like the white hairs associated with other white markings and patterns, the white hairs of a rabicano may be rooted in unpigmented skin cells. However, the genetic and developmental controls of such roaning is presently poorly understood, and has not yet been formally studied.
While rabicano itself does not produce white markings on the face and legs, it is associated with some of the numerous sabino patterns, one of which has been mapped to the KIT gene. Other color patterns mapped to KIT include tobiano and true roan. This may explain the close association between rabicano and sabino, which are often observed in the same horse.
Rabicano vs. Roan
Rarely is rabicano patterning extensive enough to be confused with true roan. Rabicanos are not true roans and can be distinguished from true roans by the following:
- Roaning on rabicanos is centralized at the junction of the stifle and the flank; true roan is evenly distributed over the whole body except the points.
- Rabicanos usually have skunk tails or rings of white hairs in the tail, while true roans do not.
- Rabicano roaning often spreads, while true roans usually become darker.
- Rabicanos do not develop corn marks when their skin is damaged.
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