Nov 8, 2023 Grasping Genetics
While it's true that many can spot a roan horse, the question remains: can you distinguish between genuine roans and other phenotypes that have roaning? Join us on a journey to uncover the nuances of roan.
Many breed registries, including the AQHA, offer a limited array of options for horse registration when it comes to coat colour and pattern. There is no distinguishing betwen roan, rabicano, sabino, or any other white pattern. However, in our modern era, we are fortunate to wield the power of genetic testing, enabling breeders and horse owners to unravel the mysteries of equine genetics and make informed decisions.
A true roan is a horse with a coat pattern that presents as white hairs intermingled with coloured hairs across the body, creating a stunning contrast with the base colour. What distinguishes roan from other patterns is that it is uniform throughout the body and spares the horse's head and legs, making those areas less effected by the roaning effect. This trait is unlike many other genetic modifiers such as the cream gene, or champagne, which dilute the horse’s entire body.
While roan can appear on horses of any base colour, it's most easily discerned on darker coats due to the stark contrast it creates. Roan, not unlike other genetic markers, can also be a expressed atop a number of other genes that can make it difficult to distinguish exactly what is going on. A red (sorrel/chestnut) horse with the roan gene is commonly referred to as red or strawberry roan, black base with the roan gene are commonly referred to as blue roan, and bay bases are simply called bay roans. The trio of core bases aside, any other combination is just referred to as base (plus modifiers) + roan. For example, a Palomino horse that is heterozygous for the roan gene (n/Rn) is a 'Palomino Roan.' It's also important to note that on lighter combinations, such as palomino or cremello, identifying the roaning effect can be more challenging due to the reduced contrast.
Roan is a complete gene, in that heterozygous and homozygous differ only on paper and how they can reproduce, but will not appear differently to the naked-eye. A heterozygous roan horse will carry one copy of the gene (n/Rn), where homozygous horses will have two copies of the gene (Rn/Rn) but you will not be able to tell from simply looking at them. For more information regarding heterozygous and homozygous traits, read our artice here.
The roan gene itself is dominant, which means that for it to be passed on to offspring, at least one of the parents must carry the roan gene (meaning they must be heterozygous (n/Rn)). One of the interesting aspects of a true roan horse is that it is often born with a solid coat colour, though not always. In these cases, when the horse sheds its first foal coat that the roan pattern begins to emerge. In these horses, the roan colouring remains consistent and doesn't lighten as the horse ages – though you may see seasonal changes due to longer or shorter hair-coats. This remarkable permanence sets roan apart from other coat patterns, where permanent changes over time are not uncommon, such as the gray gene.
Another intriguing aspect of roan is its reaction to injuries. When a roan horse sustains an injury, the subsequent healing process results in the hair growing back in its base colour. For example, if a red roan horse experiences a cut or abrasion, the hair that regrows in the affected area will be the original solid red (chestnut/sorrel) colour. In contrast, injuries to horses with different coat patterns may result in hair growing back white. In the example above, Funny B Blue Muchaman, you can see these injury marks, or 'corns' on his neck.
While roan is a distinct coat pattern, it can sometimes be confused with other white markings that are caused by different genes. For instance, the American Quarter Horse Association recognizes sabinos and rabicanos with sufficient ticking as roans, as there is no separate colour category for these patterns. Unfortunately, this means that horses are improperly or incompletely registered all the time, forcing horse owners to invest in genetic testing to uncover the truth of their horse. However, some specific colour registries such as the American Roan Horse Association only allow registration with confirmation of roan zygosity present (though not in all cases, but at least in the case of my mare which was registered as a red dun with the AQHA, as I was unable to add 'roan' to her papers at time of registration; she is in fact a red dun roan).
It's essential to distinguish between a true roan, the roaning effect caused by the sabino gene, and rabicano patterns. These are the most commonly confused patterns for true roan. While sabino and rabicano can create a roaning effect on the body, they are not products of the roan gene. In a true roan, the 'Rn' gene is responsible for the distinct roaning pattern. Sabino, on the other hand, often presents with facial white markings, a white chin spot, white socks on the legs, and body roaning – making it distinguishable from a true roan. Transversely, a rabicano marked horse will often have vertical “barring” on the ribs, roaning/ticking intensified on the flank, and a “coon” tail. True roan horses (unless they are in combination with rabicano) will not have these traits. Rabicano horses also don’t have roaning uniformly throughout their bodies like a true roan horse will. Another distinct marker is that many rabicano horses won’t have any white hairs on their necks/shoulders where a true roan horse will.
Rabicano is a distinctive horse coat pattern featuring white ticking which is often confused for roan, it is characterized by white hairs concentrated primarily at the tailhead and flanks, where the hindquarters meet the body. The term "rabicano" originates from the Spanish words "rabo" for "tail" and "cano" for "white" – which is a main component of this gene. While minimal rabicano expression may include a few white hairs in these regions, horses with chestnut or chestnut-based coats are more likely to exhibit extensive white patterns. It's worth noting that rabicano is a roaning pattern, distinct from true roan, and its genetic mechanisms are not yet fully understood. That said, lets have a look at a classic visual representation of rabicano:
No roaning present on shoulder or neck at all, though some rabicanos will have it present if they are maximally expressed
Vertical rib-barring present, this is a distinct characteristic of rabicanoism that does not appear on roans (note: on roans that do NOT also carry rabicano)
Heavier roaning in areas of the body that don't appear uniform throughout, many rabicanos will have more intensely roaned flanks where true roan horses will be uniformly roaned over their body (excluding legs / faces)
The classic rabicano skunk tail is present, true roan horses may have white in their tail but it will not have the very distinctive "stripes" that are characteristic of the rabicano skunk tail
Sabino patterns display roaning, white patches with uneven or jagged borders, belly spots, white beyond eyes or chin, white above knees or hocks, and splash-like marks. Some show partial roan on the body, often the barrel and flanks. Sabinos can also have one or two dark legs but often feature four white legs. The sabino markings can also range from subtle facial or leg white to nearly all white coats in those that are maximally expressed. With all of that noted, let's take a look at a stallion who carries the sabino gene:
Lip-white; roaning is also present on the cheeks
Some neck spotting and roaning present
Classic sabino spotting on the belly accompanied by more light roaning; zero "barring" present on barrel
Much of the horse's body has very light roaning, aside from shoulders, neck, and hip
Note there is no skunk tail or tail-white present at all
High white stockings with jagged edges present
With what we now know about Roan, Rabicano, and Sabino – let's see if we can decipher what's going on with a horse that has a series of markers that point to multiple genes. Technically speaking, a horse could be a roan sabino rabicano, and possess all three genes, but we'll start with a stallion that has two of the three:
Lip-white; sabino markings are present on the cheeks, throat-latch, and neck
No roaning on shoulders, but there are sabino markings present
Classic sabino leg markings with jagged or laced edges
Loudly expressed sabino belly spotting with accompanying roaning
Deeper roaning or ticking present at flank, a rabicano characteristic
Skunk tail present, consistent with rabicano markers
We feel that this is worth mentioning, even though this is much more common in the Thoroughbred world. There is a common misconception that leads owners/breeders to refer to and register their foals as gray/roan but are simply gray horses in the stages of progression of the gray gene. Now, that is not to say that a gray horse could not also possess the roan gene (ref. Two Legitt who is a gray (buckskin roan) stallion); but in this instance, we have a gray colt that is likely not roan at all:
Head is graying out as well as the rest of the body; not all horses gray out in the same areas at the same speed, but this colt is an ideal example of the confusion surrounding gray horses within the Jockey Club
Legs are also graying out at near or the same speed as the rest of the body; though this isn't always the case, I have a gray gelding myself who still has dark spots on his knees and hocks
The body, while uniform, is simply graying out; we see no signs of barring (rabicano), no signs of deeper or more intense patches of roaning which leads us to believe that (without genetic testing in-hand), this is likely a base + gray horse only, with no roan or roaning patterns present
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Founder, StallionCompare.com | Creative Director
Natashya, the founder of StallionCompare.com, is a dynamic force in both the equine and creative industries. As a lifelong equestrian, Natashya’s journey with horses began with Quarter Horses in her hometown in British Columbia, Canada. During her college years she took a brief (and eye opening) hiatus from Quarter Horses to work in the Thoroughbred industry – returning to the AQHA circuit as a young adult. Natashya was also able to reconnect with the quarter horse industry through design. She worked with former owners of Pleasurehorse.com and Show Horse Today on their design needs prior to Robyn Duplisea purchasing the business. Natashya also worked at Horse Canada (HPG) as the Creative Director for many monthly, quarterly, and annual equine magazines. Her passion (read: obsession) for breeding, genetics, and equine pedigrees ran ever-increasingly deep, which lead her to create StallionCompare.com.
Beyond her equine pursuits, Natashya is the Creative Director & Co-Founder of a leading design agency known for its boutique, customer-focused approach. With her expertise, she blends creativity and technology to make a lasting impact in both horse breeding and design.
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