A roan horse is characterized by a specific coat color pattern. Most roan horses will have a coat that is mixed with white hair and colored hair that is common to their breed. The “points” of the horse, however, are usually a solid color, without the white hair. That means the mane, tail, and lower legs tend to be a darker color than the remainder of the coat that covers the horse.
Roan patterning is a dominant inheritance. A majority of horse breeds allow for roan horses to be registered, though not every breed may allow a roan horse to produce purebred offspring. Although the reason for the roan coat is not known beyond the fact that it is a genetic mutation, DNA testing is available to determine the likelihood of roan characteristics for several different horse breeds.
Roan coloration is always present at birth, but their coloration may slightly alter as they grow older and their primary coat begins to grow in.
Many roan horses will have their coats become a different shade in the warmer and colder seasons, moving from light to dark or dark to light, depending upon the other color involved. Unlike gray horses, however, the roan coat stays consistent. Roans do not become lighter or darker in coat color as they get older.
What Are the Different Shades of Roan?
Although the mixture of coat colors involves white and a base color, the actual shading of the horse can be quite unique. The background color is often used to describe the exact type of roan that the horse happens to be.
There are three common types of roan coat coloring that are seen throughout most horse breeds today.
Blue roan is a coat color that has a very dark underlying coat that is evenly mixed with white coat hairs. This gives the coat color a bluish tone when sunlight strikes it. An authentic blue roan has a black base coat color, but any “dark” base coat color may be referred to as a blue roan.
Red roan is a coat color that involves a bay or chestnut primary coat that is mixed with the white hairs. Some horses may have a light red tone to their coat, which makes them appear to be slightly pink when the sun hits the hair. In the past, these red roan horses were sometimes called “strawberry roans.” Darker chestnut or bay colors may also be called “honey roan” or “lilac roan,” depending upon the breed.
Bay roan is a coat color that is specific to the bay coat color. Some breeds still incorporate this coloration into “red roan,” but Quarter Horses, Paint Horses, and other breeds have given this color its own category for breeding and registry purposes.
There are actually 3 different shades of bay roan that are possible in many horse breeds. There is a brown base color with black points with a dark shade, the same with a lighter shade, and then a bay roan that has some white hair in the mane and tail as well.
Most roan horses show more white hair during the summer months and have darker hair with a winter coat, but horses that do not grow a thicker coat for winter may seem lighter.
How Roan Horses Are Genetically Possible
The roan coat color is a simple dominant trait. It is usually symbolized through an Rn allele. The roan gene, or R, does not appear in the offspring of two parents that are not roan, even if there are roan horses in the offspring’s lineage.
If both parents have the Rn allele, then the offspring they produce is guaranteed to be a roan horse. There are homozygous and heterozygous roans (two parents being roan or one parent roan), but both types are identical in appearance.
When one of the parents is roan, then the base color for the coat becomes a combination of the coat genes passed to the horse. That is how the different colors become possible, including rare roan colors, such as palomino or buckskin roans.
Dominant traits cannot skip a generation. There are times when it appears that roan coloration might skip a generation, but one of the parents is slightly roan and it may not be noticeable. Extensive white markings or gray coloration can also “hide” roan coat attributes to create a foal that is a “surprise” roan.
Certain genetic influences may also cause some horses to be a “false” roan. Sabin, rabicano, and other coloration influences, such as varnishing marks or leopard complex colors, may create the appearance of a roan horse. “False” roans are not considered an actual roan horse.
DNA testing that can detect the Rn allele is available and the mutation that causes the coat coloration has been assigned to ECA3, which is a specific horse chromosome. Zygosity tests are available and reliable for certain breeds that allow for roan horses to be produced with greater reliability as well.
The Problem with Gray Horses and Roan Horses
It is not uncommon for gray horses to be mistaken for roan horses. Both types of coats possess similar characteristics, and since gray is a common coat color, it is not unusual for an owner or handler to believe they have a roan horse because of the way it looks. Many gray horses are actually registered as bay roan horses when they are young.
Gray foals can be born of any coat color, including roan, without there being an indication that the coat will change color as the horse reaches adulthood. That also complicates the registration process, especially if the foal does not come from a lineage that includes gray horses in recent generations.
What defines a gray coat from a bay coat is that the coat of the horse with gray will become consistently lighter over time. Mature gray horses may keep none of their original coat color and look like a horse that is pure white. The color of the eyes and the skin remain unchanged, however, and that can give the “points” of the horse a look that is reminiscent of roan horses.
Even if a roan horse has the gray gene, their coat color does not develop more white or gray hair over time. At best, this gene causes the horse to look slightly lighter or darker with each passing season as the coat changed.
Roan horses provide a unique look to many horse breeds. All can be registered, but some may only be permitted to register as a color breed or through a roan horse association. Except for the unique coat, all the other breed expectations apply to each horse.