The Inheritance of White Facial & Extremity Markings

Painted Ponies
Sand Wash Basin, Colorado
ยฉequus ferus. wild horse photography

Some background history

White markings in horses serve no biologic purpose, nor are they an adaptation to avoid predation or increase survivorship. On the contrary, white markings on a horse can make it easier for predators to detect them due to the way light interacts with different colors and how animals perceive contrast in their environment. Dark colors, such as black and brown, tend to absorb more light and blend more seamlessly into natural surroundings, whereas white reflects more light, making it more conspicuous, especially in low-light conditions or against darker backgrounds (Caro, 2005). This increased visibility can make a horse with white markings stand out from the rest of the herd, drawing the attention of predators.

Additionally, many predators rely on motion detection and contrast sensitivity rather than color perception when hunting. Studies on animal vision suggest that predators like wolves and big cats have dichromatic vision, meaning they perceive colors differently than humans, primarily distinguishing between blue and yellow wavelengths while having difficulty differentiating reds and greens (Jacobs, 1993). Because white markings create a stark contrast against darker coat colors or natural surroundings, they can enhance the visibility of movement, making a horseโ€™s motion more detectable to a predator’s keen eyesight.

In some environments, particularly in wooded or shadowed areas, a horse with large white patches may stand out more distinctly compared to a uniformly dark-colored horse, which benefits from more effective camouflage (Caro, 2016). This is particularly relevant in species where natural selection has favored solid or muted coat colors in wild equines, such as zebras, which use disruptive coloration to confuse predators (Ruxton, Sherratt, & Speed, 2004).

Picasso
Sand Wash Basin, Colorado
ยฉequus ferus. wild horse photography

While white markings may increase visibility in certain conditions, their impact varies based on habitat and lighting. In bright, open environments, such as snowy regions or sandy plains, white markings may offer some blending advantages. However, in forests, grasslands, or dusk and dawn lighting conditionsโ€”when many predators are most activeโ€”white markings can provide a disadvantage by increasing a horseโ€™s contrast against the environment, making it easier for predators to spot and track them.

Why White Markings are Preferred

Humans selectively bred horses for white facial and leg markings due to a combination of aesthetic, practical, and genetic factors. These markings were often associated with visibility, tradition, and cultural significance, as well as linked to specific genetic patterns.

1. Increased Visibility

One of the primary reasons for selecting horses with white markings, especially on the face and legs, was to enhance their visibility in low-light conditions. White facial blazes and leg stockings made it easier to identify individual horses, particularly in herds or during nighttime activities (Gower, 1999). This was especially beneficial for cavalry, working horses, and herding livestock in dimly lit environments.

2. Aesthetic and Cultural Preferences

Throughout history, different cultures favored distinct coat patterns. In many European and Middle Eastern traditions, white markings were seen as noble and desirable. Medieval knights often preferred horses with white blazes and stockings because they were considered more striking and prestigious (Bennett, 1998). Similarly, in North America, flashy white markings became popular in breeds such as the American Paint Horse and Pinto horses.

3. Association with Temperament

Some studies suggest a correlation between coat color, white markings, and temperament. While anecdotal, many horse breeders believed that certain markings were linked to docility or alertness (Haase et al., 2021). This perception may have led to selective breeding for specific markings as a means of predicting and influencing behavior.

4. Genetic Linkages and Breed Standards

White facial and leg markings are largely controlled by genes affecting pigmentation, particularly the KIT and MITFgenes (Brooks et al., 2007). As breeding programs developed, horses with desirable traitsโ€”including markingsโ€”were preferentially selected. Some breed registries, such as the American Quarter Horse Association (AQHA), permit or even favor white markings within certain limits, reinforcing their propagation through generations (AQHA, 2023).

5. Cultural and Superstitious Beliefs

Certain markings have been historically linked to superstitions. For example, the “badger face” marking (inverted white blaze) was considered lucky in some cultures, while others believed extensive white on the face (e.g., a bald face) could indicate poor vision or sensitivity to sunlight (Sponenberg, 2009). These beliefs influenced breeding choices in different regions.

Badgerface (center)
McCullough Peaks, Wyoming
ยฉequus ferus. wild horse photography

Humans bred horses to have white facial and leg markings primarily for their visibility, aesthetic appeal, perceived temperament traits, and genetic linkages. Over time, these preferences became ingrained in breed standards and cultural traditions, leading to the continued propagation of these markings in many modern horse breeds.

White Markings in Equine Ancestry

The absence of white markings in wild horses, such as the Przewalskiโ€™s horse, suggests that mustangs in America are not descended from native horses can be supported by several points drawn from the provided references.

  1. Lack of White Markings in Wild Horses: Przewalskiโ€™s horse, the last truly wild horse species, lacks white markings, indicating that such traits are not inherent to wild equine populations. As stated, โ€œthe markings were not present, or were very rare, in the primeval wild horse, as evidenced by their absence in Przewalski’s horseโ€ (Woolf, 1991, p. 3). This suggests that white markings are a trait associated with domestication rather than a natural occurrence in wild equines.
  2. Selective Breeding and Aesthetic Preferences: Domestic horses have been selectively bred for various traits, including coat color and markings, primarily for aesthetic purposes. The document mentions that โ€œwhite markings are assumed to be flashy, highlighting the limb action which is particularly important in showsโ€ (Stachurska & Ussing, 2012, p. 75). This selective breeding has led to the proliferation of white markings in domesticated horse breeds, which are not found in their wild counterparts.
  3. Genetic Evidence of Selective Breeding: The presence of white markings in domestic horses is associated with several genetic loci that are not prevalent in wild populations. The genetic basis for white markings is multifactorial and involves complex inheritance patterns, as discussed in multiple studies that highlight the heritability and genetic underpinnings of these traits (Woolf, 1990, p. 250). In contrast, wild horse populations like the Przewalskiโ€™s horse show a different genetic makeup, lacking the alleles responsible for white markings.
  4. Implications for Mustang Ancestry: If mustangs were directly descended from native horses in the Americas, one would expect to find similar genetic traits, including white markings. However, the absence of such markings in their wild ancestors suggests that mustangs likely descended from domesticated horses, which were selectively bred for these traits in Europe and brought to the Americas by European settlers. The genetic diversity and presence of white markings in mustangs can thus be attributed to the introduction of domestic horses with these traits rather than a lineage from native equines.

In conclusion, the lack of white markings in wild horses like the Przewalskiโ€™s horse supports the notion that mustangs, as domesticated descendants, inherited these traits through selective breeding practices focused on aesthetics, rather than through lineage from native American horses. This argument is reinforced by genetic evidence indicating that the selective pressures for coat color and markings are a product of domestication rather than a natural evolution in wild horse populations. There are other reasons we know mustangs are descended from domestic horses, but that a topic we will touch upon later in this post.

PJ (Picasso Junior)
Sand Wash Basin, Colorado
ยฉequus ferus. wild horse photography

Inheritance of White Markings

The white facial and leg markings on horses are described as multifactorial, meaning that the genes are not the only factor that determines their inheritance. It has been found that these markings are controlled by several genetic loci and at least some of the genes involved include MC1R, KIT and MITF. 

1. Multifactorial Inheritance: Some white facial and leg markings are not inherited in a simple Mendelian fashion but rather by a polygenic or multifactorial inheritance system where many genes interact to produce the phenotype. This pattern of inheritance suggests that the frequency of white markings can vary greatly between individuals because of the additive effects of several alleles (Woolf, 1990; Rieder et al., 2008). 

2. Key Genes Involved: Melanocortin 1 Receptor gene (MC1R): Mutation of this gene product causes changes in coat color and plays an important role in the extent of white markings especially in chestnut horses where they have more white markings than other colors (Woolf, 1990; Haase et al., 2013). KIT: The KIT gene is also responsible for the development of the white marking and the size of the area with white marking. Many alleles at this locus have been found to be associated with various forms of white spotting including dominant white (Haase et al., 2013; Rieder et al., 2008). MITF (Microphthalmia-associated Transcription Factor): This gene has been found to be responsible for certain white spotting phenotypes including the splashed white phenotype (Hauswirth et al., 2012). 

3. Genetic Correlation: Studies have shown that heritability for white markings is high, suggesting genetic basis. For instance, heritability estimates for facial markings can be 0.69, and total leg markings can be 0.68, which indicates that genetics is a significant determinant of these traits (Woolf, 1990; Rieder et al., 2008). 

4. Environmental Factors: In addition to genetic influences, environmental factors and stochastic (random) events can also affect the development and manifestation of white markings. This includes the possibility of developmental noise, which are stochastic variations that occur during embryonic development that may result in the variation in the migration and survival of melanoblasts (Mintz, 1974; Woolf, 1995). 

5. Complex Interactions: The interaction between the basic coat color (which is determined by MC1R and Agouti loci) and white markings is also rather complicated. For example, chestnut horses (e/e) are typically more heavily marked than bay (E/ โ€“) and black (a/a; E/ โ€“) horses, which shows the role of other genetic factors (Woolf, 1991). 

Bay Tobiano
Mccullough Peaks, Wyoming
ยฉequus ferus. wild horse photography

The Next Generation

The inheritance of white facial and leg markings in horses is a complex trait controlled by several genetic loci and environmental factors with significant contributions from MC1R, KIT, and MITF genes and their products, which result in various phenotypic outcomes. The heritability of facial and leg markings is fairly high, with the heritability estimates for facial markings being estimated at 0.69 and for limb markings at 0.68, and the overall heritability for both facial and limb scores can be up to 0.77 (Woolf, 1990; Stachurska and Ussing, 2012). These markings are caused by several loci, and the two most important genes have been identified as MC1R and KIT that are involved in pigmentation. The MC1R gene codes for the receptor that regulates type of melanin produced while the KIT gene is associated with white spotting patterns (Rieder et al., 2008; Haase et al.,2013). Furthermore, it has been postulated that the expression of white markings is not only dependent on genetic factors but also on stochastic events that take place during embryonic development that affect melanoblast survival and migration (Woolf, 1990). This complexity suggests that other factors, including environmental factors, may also contribute to the variation in phenotypic expression of white markings in different individuals (Woolf, 1995; Rieder et al., 2008).

White markings can be inherited from parents to offspring. White markings in horses are known to be influenced by genetic factors, especially the mutation of certain alleles at certain loci. For example, a study showed that if both parents have white facial markings, the offspring are likely to have these markings and 61.8% of such offspring will have white markings (Document: Encina et al. – 2024). On the other hand, if both parents are without white markings, then a smaller percentage of the offspring (22.6%) have these markings.

Violet
Sand Wash Basin, Colorado
ยฉequus ferus. wild horse photography

Size matters?

The size of white markings on legs in horses is dependent on genetic and non-genetic factors. Key points include:

1. Genetic Factors: The heritability of white markings is quite high, and the studies have shown that the heritability values are between 0.68 and 0.77 for different parts of the body (Woolf, 1990; Rieder et al., 2008). The MC1R, KIT, and MITF genes have been associated with the frequency of white markings. For instance, the mutation of the recessive allele of the MC1R gene, which is responsible for the chestnut coat color, has been associated with more extensive white markings (Negro et al., 2017; Haase et al., 2013).

2. Interaction of Genes: There are interactions between different genetic loci such as MC1R and KIT, where the genetic control of the quantity of white marking depends on the base coat color of the horse (Patterson Rosa et al., 2022; Cuffe, 2024).

3. Environmental and Stochastic Factors: Other factors, which can be regarded as environmental variables, affecting the intrauterine development of the horse, can also influence the expression of the phenotype of white markings. Stochastic events that affect the survival, movement and mitosis of melanoblasts (the precursor of melanocytes) contribute to the variation in white markings (Woolf, 1995; Stachurska and Ussing, 2012).

4. Sex and Coat Color: It has been found that males have slightly more white markings than females and the base coat color greatly affects the frequency of white markings with chestnut horses having more extensive markings than bay or black horses (Woolf, 1990; Rieder et al., 2008). In summary, the quantity of white in leg markings is controlled by genetic inheritance, particular gene interactions, environmental factors and stochastic events that occur during development.

Thor
Sand Wash Basin, Colorado
ยฉequus ferus. wild horse photography

The Base Coat

Also, different coat colors have different effects on the chances of white markings in offspring. For example, chestnut horses are more likely to have white markings than black horses (Document: Encina et al. – 2024). In general, although genetics is an important factor in the expression of white markings, other factors like environmental conditions and developmental processes also play a role in the expression of these markings. This indicates that the above mentioned genes are involved in the determination of the shape of white markings, such as a star or a blaze.

For example, chestnut horses, which have a specific genotype (e/e), have more extensive white markings than bay or black horses and the amount of white marking is generally higher on these horses than on other horses (Woolf, 1990; Rieder et al., 2008; Haase et al., 2013). Furthermore, the heritability of markings suggests that the extent and perhaps the shape of these markings can be passed down from generation to generation and that certain genetic combinations are more likely to result in more pronounced markings (Woolf, 1990; Rieder et al., 2008). Therefore, even though there are stochastic events that can lead to the final appearance, the genetic predisposition to certain shapes of stars and blazes is indeed inherited. Specific coat patterns are associated with specific facial markings?

Horse coat patterns are accompanied by specific facial markings due to genetic control of pigmentation. Here are some notable associations:

1. Tobiano Pattern: Tobiano horses are homozygous for white and have large patches of white that cross the spine and have face marks that are usually star or stripe like. This is associated with the KIT gene which is involved in white spotting phenotypes (Haase et al., 2013).

2. Sabino Pattern: This pattern has a patchy white marking on the face and other parts of the body and is similar to the leopard complex. The KIT gene is also involved here, that is through mutations that result in different levels of white marking including facial patches (McFadden et al., 2024).

3. Splashed White: Horses with this type of splashed white pattern have a lot of white on the face including up to a full blaze or completely white face. This phenotype is caused by mutations in MITF and PAX3 genes (Hauswirth et al., 2012).

4. Leopard Complex: Horses with this pattern, such as Appaloosa, may have distinctive facial markings with their coat pattern. The gene that causes the leopard spotting is TRPM1 and this can include facial spots (Neves et al., 2017).

5. Frame Overo: This pattern has patchy white patches which do not run across the back and may have facial markings. This is associated with the EDNRB gene which can result in significant white facial markings (Patterson Rosa et al., 2022).

Bay Tobiano Stallion
Onaqui/Great Desert Basin, Utah
ยฉequus ferus. wild horse photography

Blue Eyes

The analysis of the coat patterns and facial markings shows that genetics is a crucial determinant of equine coat colour and patterns, and certain genes can lead to specific phenotypic characteristics such as blue eyes. Blue eyes are usually associated with certain white markings in horses. In particular, horses with the splashed white phenotype, which is characterized by significant white markings, have blue eyes. This is explained in the literature on the genetics of white spotting patterns where mutations in genes such as MITF and PAX3 are responsible for both the splashed white markings and blue eyes (Hauswirth et al., 2012; McFadden et al., 2024). Also, in the context of the Lethal White Overo (LWO) syndrome, which is also characterized by white markings, affected horses may have blue eyes as well (Neves et al., 2017).

Van Gogh, Tavi, Michaelangelo, Owl
Sand Wash Basin, Colorado
ยฉequus ferus. wild horse photography

Cut-outs, reverse colour, negative shapes, superimposed colour…

White marking with โ€˜cut-outsโ€™, or the base color seen within the blaze, similar to freckles, but on a larger scale are inherited. The body color โ€œcut-outsโ€ in a white blaze on horses, which are the areas of depigmentation, are caused by mutations in genes regulating the migration and differentiation of melanocytes, the pigment producing cells of neural crest origin. Indeed, mutations in genes such as MITF (Microphthalmia-associated transcription factor) and PAX3 (Paired box gene 3) have been linked to splashed white phenotype, which is characterized by extensive white markings including โ€œcut-outsโ€ or unpigmented areas in the coat.

These traits are inherited in a composite fashion. Some white spotting patterns, including splashed white, can be inherited in an autosomal dominant manner; however, the expression can be highly variable among horses with similar pedigree because of the involvement of other genetic factors and possibly environmental factors. The inheritance is not strictly monogenic since many mutations can contribute to the final phenotype and thus result in varying levels of depigmentation from minimal to near complete (Hauswirth et al., 2012, Neves et al., 2017). In summary, the โ€˜cut-outsโ€™ in a white blaze are the result of particular genetic mutations that affect the development of melanocyte and these traits can be inherited, but the inheritance is not very clear.

Picasso
Sand Wash Basin, Colorado
ยฉequus ferus. wild horse photography

Variations in a horseโ€™s health including skin and coat conditions may also affect how much white markings are seen in its life. In summary, the variability of white markings that come and go during the lifetime of a horse can be explained by the genetic, stochastic developmental events, environmental factors, and the health of the horse. Blazes or partial blazes on horsesโ€™ faces are forms of white facial marking and their inheritance is quite complex. According to Woolf (1990), the existence and intensity of white markings including blazes can be influenced by several genetic loci and the frequency of these markings may vary among the offspring depending on the genetic contribution of the parents (Woolf, 1990, p. 250-256). However, the patterns of white markings can be complicated and horses with highly marked parents may have more genes that cause white markings and tend to pass on similar markings to their offspring (Woolf, 1990, p. 250-256). Therefore, if a horse has a broken or incomplete blaze, it is possible that this trait can be inherited by their offspring, but the expression of the trait may vary depending on the genes of other factors. In conclusion, although there is a genetic basis for a broken or incomplete blaze, the specific expression in offspring is not fixed and may be influenced by other genes as well as environmental factors.

Eclipse
Onaqui/Great Desert Basin, Utah
ยฉequus ferus. wild horse photography

Clean edge or jagged?

The variation in the edges of facial markings in horses, whether they appear clean or jagged, can be attributed to several factors related to the developmental processes of melanoblasts, which are the precursor cells that develop into melanocytes (the cells responsible for pigment production).

  1. Melanoblast Migration and Proliferation: The presence of clean or jagged edges in white markings is influenced by how well melanoblasts migrate and proliferate in the developing tissues. If melanoblasts migrate uniformly and proliferate evenly, the resulting markings tend to have clean edges. Conversely, if there are irregularities or disturbances in the migration and proliferation processes, this can lead to markings with jagged edges (Woolf, 1995).
  2. Developmental Noise: The concept of “developmental noise” refers to random fluctuations that occur during the developmental processes. This can lead to variations in how melanoblasts settle in the skin and hair follicles. Such random events can result in differently shaped edges of the markings, with some being more defined (clean edges) and others being less so (jagged edges) (Woolf, 1995; Stachurska and Ussing, 2012).
  3. Genetic Control: The genetic makeup of the horse also plays a significant role in how these markings develop. The interaction between multiple genes (a polygenic inheritance) affects the extent and pattern of white markings, which can contribute to differences in edge definitions (Woolf, 1990; Rieder et al., 2008).
Metoer
Sand Wash Basin, Colorado
ยฉequus ferus. wild horse photography

Half a Head… Harlequin?

Harlequin facial mark
Sand Wash Basin, Colorado
ยฉequus ferus. wild horse photography

The phenomenon where a blaze covers half of a horseโ€™s face in an almost perfect midline demarkation is probably due to the failure of melanoblasts (the cells that become melanocytes, which produce pigment) to migrate or proliferate properly during embryonic development. This migration and proliferation occurs independently on each side of the embryo to produce symmetrical or asymmetrical pigmentation patterns. If the melanoblasts on one side of the midline survive and proliferate while those on the other side do not, this can result in a clearly demarcated blaze covering one half of the face. This condition represents the concept of โ€˜developmental noiseโ€™, where random events during development can result in alterations in pigmentation. This explanation is in conformity with the fact that such markings are genetically and environmentally determined (Woolf, 1990; Mintz, 1967, 1974).

Destiny
Sand Wash Basin, Colorado
ยฉequus ferus. wild horse photography

The Environment

The environment can greatly affect the phenotypic expression of white markings in horses through genetic and epigenetic changes. In particular, the migration and proliferation of melanoblasts, The cells that produce melanin in the skin are referred to as melanocytes and these cells migrate from the neural crest to their destination in the skin and hair follicles during early embryonic development. Specifically, the migration and proliferation of melanoblasts, The cells that produce melanin in the skin are referred to as melanocytes and these cells migrate from the neural crest to their destination in the skin and hair follicles during early embryonic development. However, environmental factors and epigenetic mechanisms can also affect the development and function of the melanocytes and, therefore, the formation of white markings. Stochastic factors that alter gene expression during early development can also influence the phenotype of the markings. Furthermore, epigenetic mechanisms such as DNA methylation, histone modifications, and microRNA activity can influence gene expression without affecting the underlying DNA sequence. The environment can also influence the development of white markings through stochastic (random) events that occur during melanoblast migration and survival. Epigenetic mechanisms such as DNA methylation and histone modifications can also affect gene expression in response to environmental factors. Together, these genetic and epigenetic mechanisms help to determine the pattern of white markings in horses. The environment can also cause white markings through stochastic (random) events that affect the development of melanoblasts and their survival.

Environmental factors can also influence gene expression through epigenetic mechanisms such as DNA methylation and histone modifications. These two types of mechanisms acting in concert determine the configuration of white markings in horses. The environment can also lead to white markings through stochastic (random) events that affect the development of melanoblasts and their survival. Epigenetic mechanisms can also be involved in the modulation of gene expression in response to environmental cues through DNA methylation and histone modifications. Both of these types of mechanisms are involved in the control of white markings in horses and they act in concert to determine the final outcome.

Three blazes and a star
Onaqui/Great Desert Basin, Utah
ยฉequus ferus. wild horse photography

The most common markings

The most common marking in horses is the โ€œhalf-stocking,โ€ which was found to be present on the left back leg in a study of Arabian and Thoroughbred horses,with a prevalence of 16.9% (Kocakaya et al., 2023). The most common facial marking in horses is typically referred to as a “star.” In studies of various horse breeds, including Arabian horses, the presence of a star marking is frequently noted. For example, in the study by Woolf (1990), different types of facial markings were categorized, and the star marking is recognized as one of the common types observed.The prevalence of white facial markings was also mentioned in the Pura Raza Espaรฑola horses, and it was mentioned that small white markings like stars are common (Encina et al., 2024).In general, depending on the breed, the star marking is one of the most common types of facial markings observed in horses.

Blazer, Frankie, Beryl, Dark Star
Sand Wash Basin, Colorado
ยฉequus ferus. wild horse photography

Mustangs are not Native (no matter what you read online)

The primary genetic reason that mustangs in America are considered descendants of domestic horses rather than a native species is that their ancestry can be traced back to domesticated horses introduced to the Americas by Europeans, not to the prehistoric native horse species native to North America.

Key Genetic and Evolutionary Factors:

1.ย ย ย ย ย ย ย ย ย Extinction of Native North American Horsesย ย ย ย ย 
Horses were first found in North America about 55 million years ago and evolved into many species. However, at the end of the Pleistocene epoch (~10,000 years ago) these horses went extinct, possibly due to climate change and hunting by early humans.This means that there was a genetic discontinuity โ€“ there were no wild horses in North America for a thousand of years.

2.ย ย ย ย ย ย ย ย ย European Reintroduction of Domesticated Horses
ย The modern Equus caballus was reintroduced to the Americas by the Spanish in the 16th century. ย These horses were domesticated breeds from Europe and not the wild horses of North America.ย ย ย ย ย ย Some escaped or were let loose, or were released, and formed feral populations, but their genetic origin is from the domestic stock, and not from the extinct native species.

3.ย ย ย ย ย ย ย ย ย Genetic Studies Confirm Domestic Origins. ย 
DNA analysis of mustangs supports their origin from Iberian (Spanish) horse breeds, with later input from other European breeds (e.g. draft horses, Thoroughbreds). Their genetic continuity with the extinct North American horse species is absent.

4.ย ย ย ย ย ย ย ย ย Legal and Conservation Classification
Mustangs are classified as feral and not wild because they are not genetically close to the prehistoric species and are descended from domesticated horses.ย The U.S. government has classified them as โ€œwildโ€ under the Wild Free-Roaming Horses and Burros Act of 1971, but from a biological point of view, they are domesticated feral animals and not a native species. In conclusion, mustangs in America are not considered to be a native species because they are descended from domesticated European horses and not the extinct native horses of prehistoric North America.

The following is a list of genetic traits that are present in true wild horses and are lacking in domestic horses: traits associated with domestication syndrome and the loss of genetic variability in regions linked to tameness and morphology. The analysis of the available data.

Fleck
Sand Wash Basin, Colorado
ยฉequus ferus. wild horse photography

Key Genetic Differences Between Wild and Domestic Horses

1.ย ย ย ย ย ย ย ย ย Greater Genetic Diversity in Przewalskiโ€™s Horse:ย The Przewalskiโ€™s horse (Equus ferus przewalskii) is considered the only living wild horse, that was never tamed.ย Genetic analyses show that Przewalskiโ€™s horses are genetically closer to their ancestral stock than domestic horses, especially with regard to the regions linked to the immune system and open environments.ย Librado et al. (2015) reported that Przewalskiโ€™s horses have unique haplotypes that are not seen in modern domestic horses, particularly at the mitochondrial DNA level.

2.ย ย ย ย ย ย ย ย ย Distinct Y-Chromosome Haplotypes:ย ย He noted that domesticated horses are suffering from a relative lack of variety at the Y-chromosome level as compared to true wild horses. Przewalskiโ€™s horses have a distinct Y-chromosome lineage that is not seen in domesticated horses (Lippold et al., 2011).

3.ย ย ย ย ย ย ย ย ย Mutation in the G-Protein-Coupled Receptor (GPR143) Gene: In a study by Gaunitz et al. (2018), it was determined that domesticated horses have been selected at genes associated with behavior, including GPR143, which is linked to visual perception and may have influenced tameness. The true wild horses, including Przewalskiโ€™s, do not have these same mutations, suggesting a difference in their sensory perception and behavioral response.

4.ย ย ย ย ย ย ย ย ย Genetic Selection in Neural and Behavioral Genes:ย Domesticated horses have been selected for tamer and less aggressive conformation through genes like SORCS1 and NRXN1 that are involved in the development of the nervous system and plasticity of synapses (Schubert et al., 2014).Przewalskiโ€™s horses do not have all of these domestication-related genetic changes and are therefore more skittish and less submissive than domestic breeds (Schubert et al., 2014).

5.ย ย ย ย ย ย ย ย ย Difference in Coat Color Genetics: The ancient wild horses (including Przewalskiโ€™s) were mostly of the dun coat color, which is controlled by the TBX3 gene and is camouflage color.ย Many domestic horses lost the dun dilution allele in the process of selecting for other coat colors, whereas Przewalskiโ€™s horses retained this ancestral trait (Ludwig et al., 2009).

Horses, including the Przewalskiโ€™s horse, do not have the genetic markers of domestication that are seen in modern horses, especially in the behavioural, neurologic, and coat colour genes. They own higher Y-chromosome diversity, have conserved immune system genes, and have not been selectively bred for tameness and coat color, which makes them different from the domesticated breeds.

Bay Stallion (thin star-irregular stripe-large snip-white chin)
Sand Wash Basin, Colorado
ยฉequus ferus wild horse photography

References
American Quarter Horse Association (AQHA). (2023). AQHA Official Handbook of Rules and Regulations.

Amarillo, TX.Avila, F., Hughes, S. S., Magdesian, K. G., Penedo, M. C. T., & Bellone, R. R. (2022). Breed Distribution and Allele Frequencies of Base Coat Color, Dilution, and White Patterning Variants across 28 Horse Breeds. Genes, 13(9), 1641. https://doi.org/10.3390/genes13091641

Bellone, R. R. (2010). Pleiotropic effects of pigmentation genes in horses. Animal Genetics, 41(s2), 100โ€“110. https://doi.org/10.1111/j.1365-2052.2010.02116.x

Belousova, N. F., Bass, S. P., Zinoveva, S. A., Kozlov, S. A., & Markin, S. S. (2020). Features of coat color and markings and impact of dun factor on Vyatka horse breed. BIO Web of Conferences, 17, 00202. https://doi.org/10.1051/bioconf/20201700202

Bennett, D. (1998). Conquerors: The Roots of New World Horsemanship. Amigo Publications.

Bianca Haase1,2, Samantha A. Brooks3, Angela Schlumbaum4, Pedro J. Azor1,5, Ernest Bailey3, Ferial Alaeddine6, Meike Mevissen6, Dominik Burger7, Pierre-Andr  ฬ e Poncet7, Stefan Rieder8, Tosso Leeb1,2*. (n.d.). Allelic Heterogeneity at the Equine KIT Locus in Dominant White (W) Horses.

Brooks, S. A., Makvandi-Nejad, S., Chu, E., Allen, J. J., Streeter, C., & Sutter, N. B. (2007). “Morphological effects of KIT gene mutations in horses.” PLoS Genetics, 3(11), e99.

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Druml, T., Grilzโ€Seger, G., Neuditschko, M., Horna, M., Ricard, A., Pausch, H., & Brem, G. (2018). Novel insights into Sabino1 and splashed white coat color patterns in horses. Animal Genetics, 49(3), 249โ€“253. https://doi.org/10.1111/age.12657

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Sabino Horse
McCullough Peaks, Wyoming
ยฉequus ferus wild horse photography
Sabino Horse
McCullough Peaks, Wyoming
ยฉequus ferus wild horse photography

Gaunitz, C., Fages, A., Hanghรธj, K., et al. (2018). Ancient genomes revisit the domestication history of       Przewalskiโ€™s horses. Science, 360(6384), 111-114. DOI: 10.1126/science.aao3297

Gower, S. (1999). Horse Color Explained: A Breederโ€™s Perspective. Trafalgar Square Publishing.

Haase, B., Brooks, S. A., Schlumbaum, A., Azor, P. J., Bailey, E., & Burger, D. (2021). “Genetics of white markings in horses.” Animal Genetics, 52(2), 140โ€“154.

Haase, B., Brooks, S. A., Tozaki, T., Burger, D., Poncet, P. โ€A., Rieder, S., Hasegawa, T., Penedo, C., & Leeb, T. (2009). Seven novel KIT mutations in horses with white coat colour phenotypes. Animal Genetics, 40(5), 623โ€“629. https://doi.org/10.1111/j.1365-2052.2009.01893.x

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Hauswirth, R., Haase, B., Blatter, M., Brooks, S. A., Burger, D., Drรถgemรผller, C., Gerber, V., Henke, D., Janda, J., Jude, R., Magdesian, K. G., Matthews, J. M., Poncet, P.-A., Svansson, V., Tozaki, T., Wilkinson-White, L., Penedo, M. C. T., Rieder, S., & Leeb, T. (2012). Mutations in MITF and PAX3 Cause โ€œSplashed Whiteโ€ and Other White Spotting Phenotypes in Horses. PLoS Genetics, 8(4), e1002653. https://doi.org/10.1371/journal.pgen.1002653

Hauswirth, R., Jude, R., Haase, B., Bellone, R. R., Archer, S., Holl, H., Brooks, S. A., Tozaki, T., Penedo, M. C. T., Rieder, S., & Leeb, T. (2013). Novel variants in the  KIT  and  PAX 3  genes in horses with whiteโ€spotted coat colour phenotypes. Animal Genetics, 44(6), 763โ€“765. https://doi.org/10.1111/age.12057

Hofer, H., & Sigrist, S. J. (2012). Coat colours and mitochondrial lineages of ancient horses to document domestication. https://api.semanticscholar.org/CorpusID:209175621

Brayley
Sand Wash Basin, Colorado
ยฉequus ferus. wild horse photography

Identification of a novel missense variant in SLC45A2 associated with dilute snowdrop phenotype in Gypsy horses. (n.d.).

Jacobs, G. H. (1993). The distribution and nature of color vision among the mammals. Biological Reviews, 68(3), 413-471.

KOCAKAYA, A., PAKSOY, Y., & ร–ZBEYAZ, C. (2023). Color and marking distribution in arabian and thoroughbred horses. Veteriner Hekimler DerneฤŸi Dergisi, 94(2), 110โ€“118. https://doi.org/10.33188/vetheder.1225758

Librado, P., Der Sarkissian, C., Ermini, L., et al. (2015). Tracking the origins of Yakutian horses and the genetic basis for their adaptation. Nature Communications, 6, 7256. DOI: 10.1038/ncomms8256

Lippold, S., Matzke, N. J., Reissmann, M., Hofreiter, M. (2011). Whole mitochondrial genome sequencing of domestic horses reveals incorporation of extensive wild horse diversity during domestication. BMC Evolutionary Biology, 11, 328. DOI: 10.1186/1471-2148-11-328

Liu, X., Peng, Y., Zhang, X., Wang, X., Chen, W., Kou, X., Liang, H., Ren, W., Khan, M., & Wang, C. (2024). Coloration in Equine: Overview of Candidate Genes Associated with Coat Color Phenotypes. Animals, 14(12), 1802. https://doi.org/10.3390/ani14121802

Ludwig, A., Pruvost, M., Reissmann, M., et al. (2009). Coat color variation at the beginning of horse domestication. Science, 324(5926), 485. DOI: 10.1126/science.1172750

Maciel, S. V. S. A., De Queiroz, V. H. O., De Oliveira, C. A. A., De Godรณi, F. N., Pereira, G. L., Curi, R. A., Costa, R. B., & De Camargo, G. M. F. (2020). Genetic heterogeneity of white markings in Quarter Horses. Livestock Science, 232, 103935. https://doi.org/10.1016/j.livsci.2020.103935

Flciky, Drifter, Vinny
Sand Wash Basin, Colorado
ยฉequus ferus. wild horse photography

Marรญn Navas, C., Delgado Bermejo, J. V., McLean, A. K., Leรณn Jurado, J. M., Torres, A. R. de la B. y R. de, & Navas Gonzรกlez, F. J. (2022). One Hundred Years of Coat Colour Influences on Genetic Diversity in the Process of Development of a Composite Horse Breed. Veterinary Sciences, 9(2), 68. https://doi.org/10.3390/vetsci9020068

McFadden, A., Vierra, M., Martin, K., Brooks, S. A., Everts, R. E., & Lafayette, C. (2024). Spotting the Pattern: A Review on White Coat Color in the Domestic Horse. Animals, 14(3), 451. https://doi.org/10.3390/ani14030451

Mongera, A., & Dooley, C. M. (2013). Of white tigers and solute carriers. Pigment Cell & Melanoma Research, 26(6), 787โ€“789. https://doi.org/10.1111/pcmr.12163

Negro, S., Imsland, F., Valera, M., Molina, A., Solรฉ, M., & Andersson, L. (2017). Association analysis of KIT , MITF , and PAX3 variants with white markings in Spanish horses. Animal Genetics, 48(3), 349โ€“352. https://doi.org/10.1111/age.12528

Neves, A. P., Schwengber, E. B., Albrecht, F. F., Isola, J. V., & van der Linden, L. de S. (2017). Beyond Fifty Shades: The Genetics of Horse Colors. In M. Abubakar (Ed.), Trends and Advances in Veterinary Genetics. InTech. https://doi.org/10.5772/65848

Pasternak, M., Krupiล„ski, J., Gurgul, A., & Bugno-Poniewierska, M. (2019). The Genetic Basis of Piebald Coat Colour in Hucul Horses in the Context of White Markings and Crypto-Tobiano as a Breeding Problem in Poland. Annals of Animal Science, 19(4), 955โ€“966. https://doi.org/10.2478/aoas-2019-0036

Pasternak, M., Krupiล„ski, J., Gurgul, A., & Bugno-Poniewierska, M. (2020). Genetic, historical and breeding aspects of the occurrence of the tobiano pattern and white markings in the Polish population of Hucul horses โ€“ a review. Journal of Applied Animal Research, 48(1), 21โ€“27. https://doi.org/10.1080/09712119.2020.1715224

Patterson Rosa, L., Martin, K., Vierra, M., Lundquist, E., Foster, G., Brooks, S. A., & Lafayette, C. (2022). A KIT Variant Associated with Increased White Spotting Epistatic to MC1R Genotype in Horses (Equus caballus). Animals, 12(15), 1958. https://doi.org/10.3390/ani12151958

Agasga (cut-out)
Sand Wash Basin, Colorado
ยฉequus ferus. wild horse photography

Petersen, J. L., Mickelson, J. R., Rendahl, A. K., Valberg, S. J., Andersson, L. S., Axelsson, J., Bailey, E., Bannasch, D., Binns, M. M., Borges, A. S., Brama, P., Da Cรขmara Machado, A., Capomaccio, S., Cappelli, K., Cothran, E. G., Distl, O., Fox-Clipsham, L., Graves, K. T., Guรฉrin, G., โ€ฆ McCue, M. E. (2013). Genome-Wide Analysis Reveals Selection for Important Traits in Domestic Horse Breeds. PLoS Genetics, 9(1), e1003211. https://doi.org/10.1371/journal.pgen.1003211

Reissmann, M., Musa, L., Zakizadeh, S., & Ludwig, A. (2016). Distribution of coat-color-associated alleles in the domestic horse population and Przewalskiโ€™s horse. Journal of Applied Genetics, 57(4), 519โ€“525. https://doi.org/10.1007/s13353-016-0352-7

Rieder, S., Hagger, C., Obexer-Ruff, G., Leeb, T., & Poncet, P.-A. (2008). Genetic Analysis of White Facial and Leg Markings in the Swiss Franches-Montagnes Horse Breed. Journal of Heredity, 99(2), 130โ€“136. https://doi.org/10.1093/jhered/esm115

Ruxton, G. D., Sherratt, T. N., & Speed, M. P. (2004). Avoiding attack: The evolutionary ecology of crypsis, warning signals, and mimicry. Oxford University Press.

Schubert, M., Jรณnsson, H., Chang, D., et al. (2014). Prehistoric genomes reveal the genetic foundation and cost of horse domestication. PNAS, 111(52), E5661โ€“E5669. DOI: 10.1073/pnas.1416991111

Sponenberg, D. P. (2009). Equine Color Genetics (3rd ed.). Wiley-Blackwell.

Stachurska, A., & Jansen, P. (2015). Crypto-tobiano horses in Hucul breed. Czech Journal of Animal Science, 60(1), 1โ€“9. https://doi.org/10.17221/7905-CJAS

Stachurska, A., & Ussing, A. (2012). White markings in horses. Medycyna Weterynaryjna, 68, 74โ€“78.

Woolf, C. M. (1990). Multifactorial Inheritance of Common White Markings in the Arabian Horse. Journal of Heredity, 81(4), 250โ€“256. https://doi.org/10.1093/oxfordjournals.jhered.a110987

Woolf, C. M. (1991). Common White Facial Markings in Bay and Chestnut Arabian Horses and Their Hybrids. Journal of Heredity, 82(2), 167โ€“169. https://doi.org/10.1093/oxfordjournals.jhered.a111053

Woolf, C. M. (1995). Influence of Stochastic Events on the Phenotypic Variation of Common White Leg Markings in the Arabian Horse: Implications for Various Genetic Disorders in Humans. Journal of Heredity, 86(2), 129โ€“135. https://doi.org/10.1093/oxfordjournals.jhered.a111542

ยฉequus ferus wild horse photography/efwhpยฎ 2025

GENETIC SERIES: The Chestnut Horse

Indiana Jones (chestnut) and Bobby (palomino). (Sand Wash Basin, ยฉequus ferus- wild horse photograp

The Genetics behind Chestnuts

All horse color is based on black, red, or a dilution or absence of these colours.

The Melanocortin 1 Receptor (MC1R) and Agouti Signaling Protein (ASIP) are both important genes involved in determining coat color in mammals, including horses.

  1. Melanocortin 1 Receptor (MC1R): Red Factor
  1. MC1R is a gene that plays a crucial role in determining the distribution of pigments in the coat.
  2. The MC1R gene is associated with the production of melanin, the pigment responsible for coloration in hair, skin, and eyes.
  3. In horses, the MC1R gene has various alleles that influence coat color. The two main alleles are the “E” (extension) and “e” (non-extension) alleles.
  4. Horses with the E allele (dominant) have a black coat, while those with the e allele (recessive) have a chestnut coat. The interactions between these alleles contribute to various coat colors.
  1. Agouti Signaling Protein (ASIP):
  1. ASIP is another gene involved in coat color regulation, and it acts by regulating the distribution of pigments in individual hairs.
  2. The ASIP gene has different alleles that affect the distribution of eumelanin (black pigment) and pheomelanin (red/yellow pigment) in the coat.
  3. The interaction between MC1R and ASIP genes determines whether a horse’s coat will have a uniform color or if there will be areas of different pigmentation such as points on a bay horse. Points refer to black located on the lowder legs, mane, tail, and ear rims.

In summary, while MC1R determines the base color of the coat (black or chestnut), ASIP influences the distribution of pigments within individual hairs, leading to variations in coat patterns. The combination of alleles at both MC1R and ASIP loci contributes to the diversity of horse coat colors observed in different breeds. Other genes and modifiers can further influence coat color such as:


The chestnut coat color in horses is determined by genetic factors. The main gene responsible for chestnut color is the extension (E) gene, specifically the e allele. Horses with at least one copy of the e allele will exhibit chestnut color.

There are two variations of the extension gene: E and e. The E allele is dominant and suppresses the expression of other color genes, resulting in a black coat. The e allele, on the other hand, allows the expression of other color genes, leading to chestnut color.

The possible combinations for chestnut color are:

  • ee: Homozygous for the recessive e allele, resulting in a chestnut coat.
  • Ee: Heterozygous, with one copy of the dominant E allele and one copy of the recessive e allele. The horse will have a black coat but can pass the chestnut gene to its offspring.
  • EE: Homozygous for the dominant E allele, resulting in a black coat.

It’s important to note that chestnut color can vary in shades, from light to dark, and may be influenced by other genetic factors and modifiers. Additionally, there are different variations of the chestnut color, such as sorrel and liver chestnut, which may involve additional genetic elements.

Breeding two chestnut horses together (ee x ee) will always result in a chestnut foal, as both parents carry only the recessive e allele. Breeding two black horses together (EE x EE) will always result in a black foal, as both parents carry only the dominant E allele.


Chestnut (No mmodifier)

Three shades of Chestnut, (Assateague Island National Seashore, ยฉequus ferus- wild horse photography)
Medium chestnut (Great Basin Desert, ยฉequus ferus- wild horse photography)
Medium chestnut ((Great Basin Desert, ยฉequus ferus- wild horse photography))
Eclipse, liver chestnut with flaxen mane & tail (Sand Wash Basin, ยฉequus ferus- wild horse photography)
Liver chestnut (Great Basin Desert, ยฉequus ferus- wild horse photography)
Zorro, a liver chestnut (Sand Wash Basin, ยฉequus ferus- wild horse photography)
Flame, liver chestnut (Sand Wash Basin, ยฉequus ferus- wild horse photography)

Okiotak, flaxen chestnutโ€‚(Pryor Mountain, ยฉequus ferus- wild horse photography)
Roobios, chesnut (Sand Wash Basin, ยฉequus ferus- wild horse photography)
Chestnut (Sand Wash Basin, ยฉequus ferus- wild horse photography)
Cimarron, chestnut with sooty in the mane and tail (Sand Wash Basin, ยฉequus ferus- wild horse photography)

THE DILUTES

PALOMINO

The Cream Dilution can either be expressed as a single dilution, or a double dilution. Every chromosome has two alleles that represent the way in which each chromosome is inherited and you receive one allele from each parent. Simply put, the chromosomes (usually represented by letters) appear in pairs. To review high school biology, these pairs are generally dominant or recessive. Dominant genes are represented by two capital letters or one capital and one lower-case. The animal appears the same (phenotype) whether they are EE or Ee. The recessive form is represented by two lower-case letters ee.

The cream gene in the single form acts upon chestnut, bay and black by diluting the red colour to cream. The Cream Colour may be light enough to appear almost white to a dark chocolate tan colour. The black is generally unaffected so bay horses horses retain the black points, and mane/tail. Black horses appear somewhat diluted- a mousey chocolate. Horses with a single Cream dilution generally have dark eyes (unless blue from paint patterns) and black skin except where there are white markings (paint markings, facial markings, and leg markings).

Echo & Bolder. (Pryor Mountain, ยฉequus ferus- wild horse photography). Both Palominos, Bolder (in back) has extensive sooty. Well known for changing colour as he aged, Bolder has the Sooty gene expressed almost to the maximum. Born light, each year he grew darker and darker.  Some liver chestnut horses that have a cream gene are called โ€œchocolate palominosโ€ and may be hard to distinguish from Sooty palominos but the chocolate palominos tend to be browner and the colour is more uniform and not scattered as we see here on Bolder.

A better view of Bolder & his brother, Echo (Pryor Mountain, ยฉequus ferus- wild horse photography)

Bobby (Sand Wash Basin, ยฉequus ferus- wild horse photography). Bobby has a light mane/tial although his base color is also light.
Khloe, palomino (Sand Wash Basin, ยฉequus ferus- wild horse photography)
Corona, a dunalino which is a palomino + dun. (Sand Wash Basin, ยฉequus ferus- wild horse photography). Corona- Palomino + Dun= Dunalino. Note the primitive markings: zebra striping on legs, dorsal stripe, shading on the neck & withers) and typical palomino colouration.
Juilette, a sooty palomino, with her mother Laramie (cremello) behind her. (Sand Wash Basin, ยฉequus ferus- wild horse photography)
Khloe (palomino), Juliette (sooty palomino), and Laramieโ€‚(cremello). (Sand Wash Basin, ยฉequus ferus- wild horse photography)
Khloe (palomino), Juliette (sooty palomino), and Laramieโ€‚(cremello). (Sand Wash Basin, ยฉequus ferus- wild horse photography)
Meteor, a palomino frame overo. (Sand Wash Basin, ยฉequus ferus- wild horse photography)
Meteor, a palomino frame overo. (Sand Wash Basin, ยฉequus ferus- wild horse photography)
Meteor, a palomino frame overo and Coronado, a liver chestnut tobiano. (Sand Wash Basin, ยฉequus ferus- wild horse photography)

CREMELLO/PERLINO

Cremello stallion. (Great Basin Desert, ยฉequus ferus- wild horse photography)
Same stallion as above. (Great Basin Desert, ยฉequus ferus- wild horse photography)
Laramie, a cremello. Note her tiny mustache)!. (Sand Wash Basin, ยฉequus ferus- wild horse photography)
Tripod, a cremello. He sustained an injury to his right hind hock as a foal which resulted in deformity. He gets around in spite of the injury. (Sand Wash Basin, ยฉequus ferus- wild horse photography)
Perlino. Not a chestnut, but rather a bay base coat- but similar to the cremellos- with darker points present. (Sand Wash Basin, ยฉequus ferus- wild horse photography)

DUNS

The Dun Dilution Factor works on all horse colours. It can appear in black, bay, chestnut, palomino, buckskin, cremello, roan, and even appears in grey horses prior to the horse greying out. Like the Cream Gene, the Dun Dilution lightens the base coat colour, adds primitive markings, but leaves black colour alone. There are so many different shades of dun and the nomenclature varies between horse breeds and regionally. We will describe them related to their base color. Black horses are unique because the resulting dun horses have a specific name called grullo/grulla. Dark bays and blacks can be almost impossible to distinguish.

A black horse with a Dun Dilution turns the horse a lighter shade, with primitive markings, and guard hairs (lighter hairs on the outside of the mane and tail). The head is usually darker. The resulting horses have a slate-blue with less red present although some can have a warm tone. They generally have a very dark head. Without genetic testing, we are only guessing at the actual chromosomes of these horses. .

Primitive markings are named for markings found on ancient horse breeds such as the Przewalski or Tappan horse. They include a continuous line from the withers to the dock (top of the tail). Other markings include wither and/or neck stripes, cobwebbing: faint stripes on the face, zebra stripes on the legs, chest stripes, and darker ear tips. Zebra stripes are the colour of the underlying coat color, so a chestnut horse has darker chestnut stripes and a bay has black zebra stripes. Lighter hair on either side of the mane and each side of the tail, called โ€˜guard hairsโ€™ may also be present.

Blizzard, light chestnut dun, aka Apricot dun (Dry Heads/Pryor Mountain, ยฉequus ferus- wild horse photography)
Blizzard, light chestnut dun, aka Apricot dun (Dry Heads/Pryor Mountain, ยฉequus ferus- wild horse photography)
Linnea, liver chestnut (R), and a chestnut dun (L). (Sand Wash Basin, ยฉequus ferus- wild horse photography)
Prince’s band: Prince (grey in back), Sunshine -chestnut with flaxen, Wonder- chestnut dun, and and Twinkle Star, a chestnut. (Sand Wash Basin, ยฉequus ferus- wild horse photography),
Corona, on the left, shows his primitive markings, dorsal stripe, and shading on his neck and withers (dunalino). Next to him is Little Thunder, a dun tobiano pinto- note the primitive markings and dorsal stripe. (Sand Wash Basin, ยฉequus ferus- wild horse photography). In the back is a chestnut stallion.
Spirit (chestnut dun), Khloe (palomino), Juliette (sooty palomino), and Laramieโ€‚(cremello).(Sand Wash Basin, ยฉequus ferus- wild horse photography)

WHITE SPOTTING PATTERNS:

ROANS

Bear, chestnut roan. Some chestnut roans have very dark tails. (Sand Wash Basin, ยฉequus ferus- wild horse photography)
Cimarron behind, and a chestnut roan stallion in front. (Sand Wash Basin, ยฉequus ferus- wild horse photography)
Liver chestnut foal. (Great Basin Desert, ยฉequus ferus- wild horse photography)
Cody, liver chestnut stallion. (Sand Wash Basin, ยฉequus ferus- wild horse photography)

(Rock Springs/Pilot Butte, ยฉequus ferus- wild horse photography)

Chestnut roan (Salt River, ยฉequus ferus- wild horse photography)
Liver chestnut roan mare with a palomino foal. (Great Basin Desert, ยฉequus ferus- wild horse photography)
Apache with a liver chestnut roan stallion. (Sand Wash Basin, ยฉequus ferus- wild horse photography)

PINTOS

Fleck, a frame overo chestnut with (Sand Wash Basin, ยฉequus ferus- wild horse photography)
Fleck with Misty (chestnut dun), and Dior (lighter chestnut dun). (Sand Wash Basin, ยฉequus ferus- wild horse photography)
Oda (chestnut mare) with her foal Y’Oda. Oda ‘s dam is Sunshine (see above). (Sand Wash Basin, ยฉequus ferus- wild horse photography)
Cowboy,โ€‚chestnut frame overo. (Sand Wash Basin, ยฉequus ferus- wild horse photography)
Picasso Junior (PJ). A liver chestnut frame overo.(Sand Wash Basin, ยฉequus ferus- wild horse photography)

Picasso Junior (PJ). A liver chestnut frame overo. (Sand Wash Basin, ยฉequus ferus- wild horse photography)
Indigo – a chestnut Tovero (likely frame overo + tobiano) and Hera, a grey behind. (Sand Wash Basin, ยฉequus ferus- wild horse photography)
Thunder, a liver chestnut and Apache, a chestnut tobiano. (Sand Wash Basin, ยฉequus ferus- wild horse photography)
Y’Oda as a young stallion, and Schatzi, a chestnut dun.(Sand Wash Basin, ยฉequus ferus- wild horse photography)
Pinyon, a frame overo stallion. (Sand Wash Basin, ยฉequus ferus- wild horse photography)
Pinyon, a frame overo stallion. (Sand Wash Basin, ยฉequus ferus- wild horse photography)
Violet. A frame overo chestnut with a sooty mane and tail. (Sand Wash Basin, ยฉequus ferus- wild horse photography)
Winchester, a chestnut tobiano that is predominantly white (Sand Wash Basin, ยฉequus ferus- wild horse photography)
Patches, a chestnut frame overo. You can see how the frame pattern runs through the center of the horse horizontally leaving the base colour intact from the withers to the tail. (Sand Wash Basin, ยฉequus ferus- wild horse photography).

Hope you enjoyed this series!
Meredith & Karen


References:
Gower, J. (1999). Horse color explained: A breederโ€™s perspective. North Pomfret, VT: Trafalgar Square. ย  ย 

Kathman, L. (2014). The equine tapestry: An introduction to horse colors and patterns. Charlotte, NC.: Blackberry Lane Press. ย 

Sponenberg, D. P. (1996). Equine color genetics. Ames: Iowa State University Press.
Presented byย 
Dr Meredith Hudes-Lowder

References:

Wild Horse Ethology: Maternal instincts, foal behaviour, and bachelor aggression.

Gypsy, Madison, Eddie, Ayita, Makwa, Josie, and Aviโ€‚(L to R: SWB, 2020)
(Clicking on the image will open the image in full resolution)

This post is not meant as gratuitous violence, but rather to demonstrate that the free-roaming horses live dangerous, and occasionally deadly lives. No animals perished in this video; the foal Avi was fine in a few days, however, he did not survive the winter. His dam, Madison, is not a maiden mare; she had a foal Juanita Rae in 2019 who survived.


After the band comes to water. Madison immediately heads to water ahead of her band. Nursing builds a considerable thirst. Her foal, Avi is left alone.


Avi standing on the berm, is approached by a bachelor stallion. You can see his mother in the lower left of the photo, and Josie in the center.


Two stallions approach Avi. Generally, when a foal is approached by older, or more dominant horses , foals will “clack”. Clacking/snapping is when a foal (and sometimes older horses) extend their neck and open and close their mouths; the term clacking comes from the sound of teeth striking. This is a subordinate behaviour that tells the dominant horse that they represent no threat. Avi did not do this during any interaction with any strange horses.โ€‚Also of note is the injury to Avi’s left foreleg and left hind leg. These injuries occurred prior to the bachelor’s attack.


Avi’s band stallion Eddie, the grey (white) stallion, confronts the curious stallion(s). Avi showed some signs of submission by extending his neck, he did not open and close his mouth audibly.


A scuffle ensues, and note that Avi is directly behind Eddie.


The three bachelors leave, and Avi wanders off to the left. This is fairly unusual foal behaviour. Foals tend to stick close to the band members.


The stallion Shooter begins to cross the waterhole. (Warning: If you don’t wish to see the foal being struck, scroll past the video below. There is no blood.)


Shooter strikes the foal. In truth, he could have easily killed the foal, but he did not. It is unusual that he deliberately went across the pond to confront the foal.


The foals walks/limps back to his band, his mother waits.


You can see the mud from Shooter’s strike on Avi’s chest. In this photo he is just over one month old. He was spotted/named on June 18, 2020 and this photo was taken July 27, 2020.


Gypsy, an older mare in Eddie’s band comforts Avi.


The foal Avi was fine a few days later. We saw him running with his band, as well as walking with no sign of lameness. His behaviour was unusual from wandering a considerable distance from his band, as well as not behaving in a subordinate manner when approached by strange stallions.


Why are bachelors aggressive? As a rule, stallions are more aggressive towards colts over fillies (Gรณrecka-Bruzda, 2023).  This makes sense because colts are future adversaries and competition for bands. A common explanation for infanticide is that the new stallion cannot afford to use his energy to look after another maleโ€™s offspring, and some may kill foals when a band is taken over (Gray, 2008).

Avi’s most likely sire is Rendezvous, and his dam Madison changed bands in October of 2019 when Eddie took over some of Rendezvous band. Avi was born in June 2020, which is a reasonably long time from Avi’s conception. This is important because stallion aggression towards foals is inversely proportional to the time spent with their dam. In other words, the time together, called consort time, results in stallions being less aggressive with mares they have spent more time together (Linklater , 1999). Presumably because the chances of the foal being theirs is higher, and so Eddie may have been more willing to risk injury defending Avi against the bachelors (Miller, 1981).

Stallions do kill foals. Bachelors are also known to inflict mortal wounds. Horses have individual personalities, and some or more tolerant than others. Avi did not demonstrate socially appropriate behaviour and showed signs of illness and injury. This alone could pose a risk for all horses by bringing predators close to an injured foal. A similar circumstance occurs in the movie ‘Cloud: Wild Stallion of the Rockies’ when another band stallions kills a foal who could not stand after birth. (https://www.pbs.org/wnet/nature/cloud-wild-stallion-of-the-rockies-introduction/29/).


Eddie’s Band July, 2020. Sand Wash Basin Colorado
Gypsy: Unknown, older mare
Madison: Bandera x Ohitika, 2016
Ayita: Tecumseh x Flame, 2016
Makwa: Josie x Orgulloso
Josie: Unknown, older mare
Avi: Madison x Rendevous, 2020
Eddie: Lucky x Tuscarora, 2014
Shooter: Flirt x Brave, 2015

References:

Gray, Meeghan. (2008). An infanticide attempt by a free-roaming feral stallion (Equus caballus). Biology letters. 5. 23-5. 10.1098/rsbl.2008.0571.

Gรณrecka-Bruzda A, Jaworska J, Stanley CR. The Social and Reproductive Challenges Faced by Free-Roaming Horse (Equus caballus) Stallions. Animals. 2023; 13(7):1151. https://doi.org/10.3390/ani13071151

Gray, M. E., Cameron, E. Z., Peacock, M. M., Thain, D. S., & Kirchoff, V. S. (2012). Are low infidelity rates in feral horses due to infanticide? Behavioral Ecology and Sociobiology66(4), 529โ€“537. http://www.jstor.org/stable/41501750

Linklater WL, Cameron EZ, Minot EO, Stafford KJ. Stallion harassment and the mating system of horses. Anim Behav. 1999 Aug;58(2):295-306. doi: 10.1006/anbe.1999.1155. PMID: 10458881.

Miller, R. (1981). Male aggression, dominance and breeding behavior in Red Desert feral horses. Zeitschrift fรผr Tierpsychologie, 57(3-4), 340โ€“351. https://doi.org/10.1111/j.1439-0310.1981.tb01930.x

2023 Mustang Walkaboutโ„ข: Day 1st

My flight was early, and a lovely car service fetched me at 3:00am. Thankfully, both of my flights were on time, and uneventful. Karen met me at the airport and we began the 4-5 hour drive to Sand Wash Basin.

We made it as far as the huge incline above Steamboat Springs, Colorado but the road was closed. No cars were permitted either direction. We found out a truck driver lost control of his rig (it is a very steep hill), and crashed. The driver did not survive the crash , we were rerouted about two hours to get around the accident. It was very sad, andI have always said, ‘as annoying as traffic may be, I’d rather be in traffic, than the cause of it‘.

We arrived at Craig, Colorado later than expected and so decided to get a hotel room for the night instead of trying to push through. I began my day very early, so it was a nice to relax and rest. The town of Craig is about an hour away from the entrance to Sand Wash Basin,

Walkabout 2020 Day Third

Another gorgeous hot day in the Basin. We are preparing for a rainy day tomorrow and no solar. We will prepare some snakkies in the solar cooker today to munch on tomorrow. But first, we go to town- Maybell, CO population 74. We get gas, ice and take advantage of the showers ($3). We do shower in the trailer, but thereโ€™s something about showering in a real shower thatโ€™s positively decadent. (Oh, and real flush toilets!)

Welcome to Maybell

We saw Comet Neowise last night Itโ€™s getting less bright, but it was amazing to see. We did not get any photos… that we know of since the photos need a lot of post production. Maybe we got lucky.


Who names horses? Well at Sand Wash, who never finds the new foal gets naming rights. Cindy was kind enough to allow us to name a new foal and since Karen and I have named a few already- we passed that on to another horse lover Sarah Broas. She named the new colt in Bronzeโ€™s band โ€˜Argonโ€™ (as in the noble has) and his dam is Reyne. We got tons of pictures on the good camera, but here is a cell phone picture.

Here are some more photos of horses we saw today.

The Mustang Walkaboutโ„ข 2023

Getting ready

It’s less than a week before our Mustang Walkaboutโ„ข begins. I have a new camera this year (Canon 5D Mark IV), and a new lens. I will bring my old Canon 7D with the new lens (24-105mm). My camera bag/knapsack weighs more than my suitcase, so I have a luggage cart (and a ton of bungee). It is compliant with carry on size, and I simply remove my iPad and I’m good for the flight. My wardrobe consists of lightweight shorts, polo shirts, work boots, Crocs for relaxation at the campsite, and the usual undergarments. Karen has all my toiletries packed in Arizona, and I bring my medications, and any personal items.

We both carry snake gaiters into the horse range, and use them if we have to tread where we cannot see our feet. The Prairie Rattlesnake is the only venomous snake found in Sand Wash Basin. They are small, reclusive, and prefer to escape, rather than fight.

My car service picks me up early Wednesday and my flight leaves at 6am. Iโ€™m on the train to New York City for a busy and fun day at my medical office. I always find it amazing that I will be in the Basin tomorrow, but seeing patients today in NYC. Stay tuned for daily blog posts from the 2023 Mustang Walkabout.

Karen is a already on her way to the Basinโ€ฆ with her faithful pug companion, Koko.

Koko has her own fan & swamp cooler!

2023 Mustang Walkaboutโ„ข: Day 9th: Thursday

Our last full day Basin went well. We saw a ton of horses, and moved the trailer to the entrance to facilitate departing early tomorrow. We drive to Denver which takes about 7-8 hours because of the trailer. My flight leaves Saturday from Denver International Airport.

The weather has been spectacular, ranging from 70s-80s 6ยฐF (21-26.6ยฐC ) and dropping to the low 50sยฐF (10ยฐC) at night. There were some thunder storms, which make the Basin extremely treacherous when the rainfall turns the roads to soup.

People ask what we out on the range, so we’ll start with breakfast. We generally stick to foods that can be made with water: oatmeal, cream of wheat, and coffee. Sometime cold cereal is eaten out of a container if we’re hungry later in the morning. We have ice most of the time (we go to town 1.25 hours away from our campsite every 2-3 three days), so our beverages are kept cool along with cheese and deli meat which constitutes lunch. We discovered ‘Snarky Tea’ this trip which is made in the sun (sun tea). They have caffeinated, and decaf options and for those of you in a more civilized environment, you can make it in the fridge.

The afternoon was spent visiting waterholes all over the Basin. Horses drink between 15-35 liters daily, more if they are lactating/pregnant, injured, or the temperature is high. We check the waterholes and the surrounding areas for horses. It can take time to find horses since Sand Wash Basin is so large (157,730 square acres/63,831,0663.square meters). After a winter of heavy snowfall, the Basin has water. The downside is many horses perished, although precise counts are not possible while the horses are scattered across the Basin because the terrain is difficult to traverse.

2023 Mustang Walkaboutโ„ข: Day 7th: Tuesday

Today was spent entirely in the Basin. The weather was iffy, so we didnโ€™t go to far from camp. We did see a lot of horses on Lookout Mountain, and a few bands came into Copper Pond.

Karen is a brilliant artist. She wanted to paint a horse from life, and Meteor and his bachelor band obliged us by standing still for an hour. It was uncanny, and almost as if they knew she was painting a portrait. The storm over the Bears Ears also held off as well. The horses: Mr. Kitty (grey), Astro (black), Orion (bay), Coronado (dark/liver chestnut pinto), Remington (chestnut), Meteor (palomino pinto). Our family named Orion when he was a wee colt, 2014.

We move the snake because they are inadvertently killed because they blend in with the road, or deliberately killed because some people are butt heads. Either way, the little fella is safe off the road.


The day ended with a rainbow and some beautiful light over the Bears Ears. Good night all!