|April 9, 2006||
Volume 1, Number 1
Welsh Article/Margaret Badger Blackert
PAINT HORSE JOURNAL DECEMBER 1998 by Frank Holmes with comments by Dr. SponenbergTRUE COLORS - The White Markings Genes And variations thereof - Horse Genetics by Ann T. Bowling and Equine Color Genetics by D. Phillip Sponenberg
|Notice: Comments, opinions and
articles in this newsletter are not necessarily those expressed by the STV Group, and are the sole responsibility of the author of such comment, opinion
This Newsletter is a new endeavor by breeder members of the WPCSA who support the original breed standards of all sections of Welsh ponies and cobs, and I have volunteered to produce it with the help of all who send me pertinent information, comments and opinions. Remember that everyone is entitled to their opinion.
Excessive white has arisen as an issue within our breed; compounding the white genes DOES produce excessive white and many Welsh ponies, currently bred from purebred parents are displaying this characteristic and appearing in larger numbers. According to the latest genetic information, even animals displaying minimal white can have the genetic makeup to produce offspring with the most excessive white markings. The LATEST findings in genetic research prove that the previously held opinion that excessive white cannot be "bred for" are archaic and opposite to the proven facts.
February, 2006 – Margaret Badger Blackert
A Little Bit of History“Piebald and skewbald are … terms that have been used to describe horses having any of the asymmetrical white patterns. Piebald refers to a black horse with any of these white spotting patterns, since piebald derives from “magpie,” a black-and-white bird.
Skewbald refers to a nonblack horse with any of these patterns. Both terms originated in Britain, where white spotting is rare on horses….the terms piebald and skewbald also ignore which specific pattern is present.”1
Originally, the stud books of the Welsh Pony and Cob Society (WPCS) (Britain) allowed any color. Wynne Davies, noted author and long-time Welsh breeder states that of the 38 stallions registered in the four sections in Volume 1 of the WPCS (Britain) Stud Book, “20 were of the hardy black, brown or bay colours, 14 were dark chestnuts, 3 were roans, and only one was grey (Dyoll Starlight). There were more greys amongst the mares (mainly in Sections A and B rather than the Cobs), the 571 mares being made up of 367 blacks, browns or bays, 109 chestnuts, 40 roans, 34 greys and 21 duns or creams.”2 Lady Wentworth, renown breeder of the 1920’s to 1940’s, wrote in a booklet PONIES, PAST, PRESENT AND FUTURE “Piebalds and skewbalds are never seen amongst correctly bred ones and heavy daubs of white are much disliked.” 3So while the piebalds and skewbalds were not clearly excluded from all sections of the WPSC (Britain) until 1950-51, they were clearly undesirable. The Foundation Stock program was still in use, and some outside blood was allowed in the WPCS Stud Books (Britain). Perhaps the reason to add the terminology to accept any color except piebald and skewbald was to keep out “Gypsy blood”, or perhaps it was to restrict the influence of the outside blood which had already been accepted. But the exclusion did not mark a change in sentiment. It was, rather, a reinforcement of the established custom.
In an Email from January 4, 2006, Wynne Davies wrote: “In WPCS UK piebalds and skewbalds were accepted (but not encouraged) up to vol 32 (1939 - 1945).... Vol. 34 (1950 - 51) states Pie and skewbalds banned.”4 In the first 39 Stud Books published in Britain, (covering to 1956 and 14,000 ponies) I found a total of four ponies of piebald or skewbald color, and one of those was Foundation Stock. Neither piebalds nor skewbalds were registered as such here in the United States.
In America, our stud books combine the years 1913 to 1955 in Volumes III and IV. This is the first document from the WPCSA I have found to say "Any color, except piebald and skewbald" (page XXIII)5. There is a publicity leaflet for Geo. E. Brown’s Stud of Welsh Ponies in Illinois, USA, 1907, which states “Colors, mostly bays and blacks, free of white marks, a few strawberry roans and steel greys.” 6 This statement indicates he considered no markings a desired trait. Piebalds and skewbalds were never encouraged in Britain, and never accepted here. Therefore, the reasoning that by removing Rule 6 the board is merely putting the rules back to the way they “used to be” is misleading, and cannot be considered a valid point.
A Little Bit of Science
Two different genes seem to exist in the Welsh which can cause explosive expressions of excessive white. The more common is the sabino, characterized by high white stockings with irregular edges pointing up the front of the hocks and the back of the knees. In combination, the white can creep up into belly spots, roaning through the flanks, and even full fledged pintos. The British Piebald and Skewbald association has a photo of a sabino pony on its website7.
It is rare that the sabino will do this, but people who breed them should consider this when making their breeding decisions. Linebreeding and crossing certain lines seems to really bring this trait out into full-fledged pintos.
The other gene is the splash gene. It is a dominant gene, so you would expect to see it more often than we do; however, it seems there are "suppressor" genes, which limit its expression8. So it can sometimes appear without warning. But there are signs to look for. "Bottom heavy" facial markings, belly spots, and high and disjointed leg markings indicate the pony may carry the splash gene. One really needs to be careful with these markings.
Squamous cell carcinoma is a real threat for equines with pink eyelids, a common trait consistent with sabino, and particularly splash patterns. I recently attended an equine ophthalmology seminar at Texas A&M University, and the speaker was berating the Pinto and Paint associations for not doing more within their breeds to try to educate owners of the problems associated with wide white facial markings.
Currently, people have been selecting for "chrome", high white stockings, and wide blazes. They are wildly popular, especially for first-time buyers who are easily influenced by flash, and competitors in large divisions trying to catch the judge’s eye. Ponies with lots of white have a greater likelihood of carrying the sabino or splash genes and therefore a greater likelihood of producing excessive white than their more conservative counterparts. Recently, I have seen the term “ sabino” used to promote ponies in advertisements, so there is no doubt that it is the current fashion. Because of its popularity, we are seeing more white in general, especially in Britain. Over there, they do not require photos for registration, so they tend to have a few registered that would not have passed our registration rules. This brings us to the root of the issue.
Current EventsWell, it seems somebody purchased a stallion and imported it here. It was registered with the WPCS (Britain). Our Purebred Registration Eligibility Rule 1 states “Ponies or cobs imported from other countries will be registered at the discretion of the Board of Directors”. Historically, the Society did not accept FS (Foundation Stock) or FS1 ponies, and would only “list” FS2 mares. In fact, in Vol. 1 of our Stud Book, the original Rule (5) states: “Our aim must be to raise the standard, and make it more difficult to obtain an entry in our Stud Book. For upon keeping up a high standard and insisting upon other desirable qualities …depend the well being of our Stud Book and the future success of our society.” 9 Instead, our current board believed they had to accept this pony. They ignored Purebred Registration Eligibility Rule 5, and at the Fall Board Meeting, they changed and effectively abolished Rule 6, which set the white limits10.
There were other issues, as well, which prompted the rule change. There is the European Union edict that all animals from registered parents must be allowed to be registered. This is so that European Union passports can be issued. This does not affect us, unless we plan to sell a pony to Europe, and even so, the United States is not part of the EU. But the WPCS (Britain) was going to have to change their rules to accept any pony with excessive white. Well, two weeks after our Board altered Rule 6, the WPCS (Britain) established a Section X for ponies that would not otherwise be accepted for registration (excess white, offspring of unlicensed stallions, etc.). This is a new classification, and the rules are still being worked out, but the British Society’s current rules indicate offspring of ponies listed in Section X are not eligible for registration in Sections A, B, C, or D, they are not allowed to show in WPCS shows, and they are not eligible for WPCS sales11. They do have papers and can get their passports, but they do not have all the rights and privileges of a registered section A, B, C, or D.
Another factor which may have weighed in on the decision- making process for members of the board is the change the American Quarter Horse Association (AQHA) made in their registration rules. The AQHA lost a legal battle against someone who wanted to register their Quarter Horse with excessive white against the AQHA rules. Whereas I'm sure the plaintiff was able to claim a large monetary devaluation because the horse was not allowed AQHA papers, I do not feel the same could be said of a Welsh Pony. Half-Welsh papers are an option, and, unlike Quarter Horses, many ponies are sold for a great deal of money without their papers. There are also Sports pony registries which will accept them. And, while the AQHA is now accepting horses with excessive white, printed on the papers, they have a disclaimer which reads, "This horse has white markings designated under AQHA rules as an undesirable trait and uncharacteristic of the breed." Rule 205, section d12. This is repeated in the judging rules. The AQHA did not exactly welcome them with open arms. Most of the other Mountain and Moorland breeds have strict color limitationsi. We are not the only ones.
Traditionally, it was assumed the piebald and skewbald restriction was to maintain purity—if a piebald or skewbald appeared, some would assume there was a mistake in the breeding shed; it was thought purebred Welsh could not produce such markings. Now, with DNA testing, we can prove the parentage. We know now that 9 Welsh Pony & Cob Society of America Stud Book VOLS. 1 and 2, 1913, p. 13. there are registered Welsh which can and do produce excessive white when the right genes get together. Leaving the restrictions in place, however, can limit the influence of these genes from generations back for generations to come. When too many of these genes get together, often through inbreeding or linebreeding, they will manifest themselves as excessive white markings. Excluding piebalds and skewbalds is not a safeguard which can be replaced by DNA tests. DNA will only ensure accurate recording of first-generation parentage. Excluding excessive white markings encourages breeders not to breed individuals so closely related that there is a good likelihood a pinto will be produced. Without the rule as a foundation, there will be no reason for Welsh breeders to exercise discretion when breeding lines known to produce excess white.
In SummarySome say only a few ponies will be affected. If this is true, then why cause such a division in the breed for so little gain. I’ve also heard the argument that nobody is required to register a pony if they feel it has too much white. I consider this view shortsighted. I believe this change will affect us all. Removing this rule contradicts and therefore weakens our breed description which continues to say “any color except piebald and skewbald.” All the literature from the Society, all the encyclopedias, reference books, and even coloring books which describe the Welsh pony as any color except piebald and skewbald will be contradicted by every piebald and skewbald pony registered. The breed description is the standard to which all Welsh ponies should be held, and the breed description must be revered, not ignored.
In addition, I find this rule change to be in violation of Article I of the By-Laws, where it says "The purpose of this Society is to maintain a Registry....while striving to maintain its purity and trueness to type and to further its welfare in every way." This purpose is repeated in the Rule Book. Allowing the registration of piebalds and skewbalds conflicts with that mandate. Having the breed description and the rules in opposition weakens the ability of the Society to ever do anything to maintain the purity and trueness to type of the Welsh Pony and Cob.
So, while there may have been several factors which led to the board’s unanimous decision to change the rules, none of them, singularly or considered all together, warrant making this decision which has such far-reaching effects on the purity, trueness to type, and health and welfare of the Welsh breed. A few may benefit by being able to register and show their pinto ponies as Welsh, but the breed as a whole, will suffer. The sanctity of the breed description, that which enables people to recognize Welsh characteristics and determine if a pony or cob has the traits necessary to be a good representative of the Welsh breed, that which the Society was established one hundred years ago to maintain, will be forever compromised with the change.
|PAINT HORSE JOURNAL DECEMBER 1998
(See Dr. Sponenberg's comments at end of article)
The sabino coat pattern, sometimes misidentified and often underappreciated, has much to offer the serious Paint
By Frank Holmes
When it comes to describing Paint spotting patterns, the term sabino (sah-BEE-no) seems to be one of the most confusing and least understood. In his book, Western Words—A Dictionary of the American West, Ramon F. Adams lists sabino as being Spanish for “a horse with a light-red, almost pink, roan-colored body and a pure-white belly.” This accurately describes one of the many variants of the pattern—the one at the median of the spectrum.
But what about the opposite ends of the palette? Minimally-expressed, the sabino pattern manifests itself in the form of white markings on the head and legs on an otherwise solid-colored horse. These sabinos are often confused with solid horses that have usual white markings. The sabinos are different in that their white markings tend to have narrow, pointed extensions up the legs or down the throat. Minimally-marked red roan sabinos are often confused with classic roan horses, with the only difference being the sabino’s extended leg and face markings. As the sabino pattern progresses, the white markings on the legs get higher, extending up the forearm and chest in the front, and the stifle in the rear. Belly spots appear that are often visible from the side. On the head, the white markings become more extensive, spreading outward over the eyes, and up from the lower lip to the throatlatch. In some instances, the head is completely white, or apron- or bonnet-faced. As the sabino pattern progresses even farther, it becomes more flecked or speckled over the entire body. The belly and the head are often completely white. This phase of the pattern is probably the one most readily identifiable as sabino. Scenic Frosted Jet is an excellent example of this type of sabino. At this point, however, the pattern again becomes somewhat ambiguous.
Sabinos with sharply-edged, large spots on their sides are sometimes confused with frame overos. Because, as the pattern progresses the white in it extends vertically over the back, some sabinos are confused with tobianos. Finally, in its maximally-expressed form, the sabino pattern evolves into an extremely white horse. Although most horses of this pattern are born as medicine hats, with dark pigment on their ears and/or foreheads, often times the pigment fades to the point of becoming virtually undetectable. White sabinos are sometimes erroneously classified as lethal whites. Nothing could be farther from the truth. Along with being misidentified, the case can be made that the sabino pattern is also grossly underappreciated. It is a pattern that is much more prevalent than commonly perceived, and one that Paint breeders have been manipulating for years with far-reaching results. To more readily understand it—from both the identification and genetic standpoints—let us first take a look at some influential sabino families, and then dissect one of those families genetically.
One smooth sabino
Nylon #360, one of the first red roan sabino Paints to be registered by the APHA, was also one of the breed’s first great show horses. (See “Smooth As Silk,” February 1996, Paint Horse Journal.) Foaled in 1961, and bred by Riley Miller of Fluvanna, Texas, Nylon was sired by Roan Bar AQHA and out of Bar’s Cherry AQHA. Roan Bar, as his name implies, was a classic red roan, with a darker head and legs. Bar’s Cherry was a solid sorrel with a bald face and three high stockings. As far as where Nylon’s sabino heritage might have come from, one need look no farther than her maternal granddam. Also owned by the Miller family, she was known as Cherry, and was an unregistered daughter of the foundation Quarter Horse sire Chubby. A recently discovered photograph of her, circa late-1940s, shows Cherry to be colored identically to Nylon. With such potent sabino genes, it stands to reason that Cherry’s daughter, Bar’s Cherry, and her granddaughter, Nylon, would have the potential to produce Paint color. Which they did. According to APHA records, Bar’s Cherry was the dam of four cropout Paints. In addition to Nylon, she was the dam of one other red roan sabino—the National Champion halter and performance stallion, Jacket Bar’s. Nylon was the dam of 10 foals. Of these, seven were colored and four were red roan sabinos. The most influential of Nylon’s produce, in terms of a genetic legacy, was C Note’s Sawbuck. “Sawbuck” was sired by the calico overo C-Note. Pattern-wise, C Note’s Sawbuck was a predominantly-white, medicine hat sabino. Bred to an equal mix of Quarter Horse and Paint mares, he sired 112 registered foals. Of these, 95, or 85 percent were colored.
Among Sawbuck’s sabino Paint get was a mare named C Note’s See Saw. Foaled in 1974, and colored exactly like Nylon, “See Saw” was out of a Breeding Stock Paint mare named Baldy Wine. See Saw was the dam of five foals, of which four were colored and two were red roan sabinos. Among the latter two was Scenic Jetalito, a 1981 stallion by Jetalito. Like his maternal grandsire, C Note’s Sawbuck, Scenic Jetalito was a predominantly-white medicine hat sabino. As he matured, the dark pigment on his ears and forehead became barely visible. Scenic Jetalito was the sire of 253 registered foals. Bred to Quarter Horse mares two-thirds of the time, he sired 84 percent color. Among Scenic Jetalito’s get is Scenic Jets Joak, a 1986 dun sabino out of Scenic Miss Joak. “Joak” is a carbon-copy, color-wise, of his sire. Bred to solid-colored mares 75 percent of the time, the predominantly- white sabino has sired 141 registered foals to date. Of these, 108, or 77 percent, are colored. Several other Scenic Jetalito sons have impressive color-getting records as well. Scenic Frosted Jet, a 1984 red roan sabino stallion out of Miss Dew Mark. Bred to mostly solid-colored mares, he is the sire of 75 percent color to date. Scenic Blondys Jet, a 1985 predominantly-white sabino stallion out of Miss Skipper Dude AQHA. He, too, maintains a three-to-one color ratio out of solid-colored mares.
From the production records of the above horses, it would appear that the sabino pattern, especially the predominantly-white one, has much to offer the breed from a genetic standpoint. As potent as the pattern appears, however, the predominantly-white, or medicine hat, sabino remains somewhat difficult to identify, let alone appreciate. To illustrate the difficulty, consider the cases of Scenic Crystal Jet, Hawkeye Sure Jet and VF Snowbird. All three horses are sired by Scenic Jetalito. All three are out of Quarter Horse mares, and all three are registered with APHA as solid white Breeding Stock horses. Scenic Crystal Jet, a 1984 white mare. The mare is the dam of seven registered foals, all overos, with five of them sired by Quarter Horses. Hawkeye Sure Jet, is a 1984 white stallion. The stallion is the sire of 16 registered foals, 11 of them overos, including five out of Quarter Horse mares. VF Snowbird, a 1985 white mare, is the dam of three foals, all overos, including one by a Quarter Horse. Registration papers to the contrary, it would appear that Scenic Crystal Jet, Hawkeye Sure Jet and VF Snowbird are all very potent, predominately-white sabinos. The Nylon line of sabinos—from C Note’s Sawbuck to The Timenator—is an extensive one, and far too long to be completely covered here. Suffice it to say that it is one of the more potent lines in the history of the breed—from both a historical and genetic standpoint.
Red roan royalty
Although rare, several unrelated families of sabino Thoroughbred have been documented. Of these, one of the best-known is that originating with Puchilingui. (See “Royalty With a Twist,” August 1996, Paint Horse Journal.)
Foaled in 1984, Puchilingui is a grandson of Raise A Native and Needles. His APHA production record shows the colorful stallion to be the sire of seven cropout Paints. The Jockey Club, which regulates the registration of all American Thoroughbreds, operates on the setinstone registration philosophy that “number-to-number gets a number.” In other words, all of Puchilingui’s Thoroughbred get, even the cropout sabinos, are eligible for registration with the Jockey Club. Due to this fact, the actual number of his get that are sabinos, and registered with the Jockey Club but not the APHA, is no doubt much greater than seven. While not as old or large a family of sabinos as the one descending from Nylon, the Puchilingui line is every bit as colorful and intriguing. Given the fact that the Thoroughbred has been selectively bred for centuries to be a basically solid colored animal, the fact that a horse like Puchilingui can even exist speaks volumes to the genetic power of the sabino gene. Carrying that thought one step farther, Puchilingui has proven his ability to sire sabino Paints of every conceivable pattern, from a variety of solid Thoroughbred and Quarter Horse mares. On one end of Puchilingui’s Paint production record, there are minimally-marked sabinos, such as Puchi Trap. Foaled in 1995, Puchi Trap is out of a bay Thoroughbred mare named She’s A Trap. Also a bay, Puchi Trap has excess white on all four legs and her head. She also has several small belly spots. In the middle, pattern-wise, among Puchilingui’s get is the 1995 red roan sabino, Jazzabelle Rae. Jazzabelle Rae is out of a sorrel Quarter Horse mare named Cybill Rae. Color-wise, “Jazzabelle” is a carbon-copy of her sire. Finally, at the opposite, or extreme white, end of Puchilingui’s cropout sabino get, there is the mare Poohlingui. Foaled in 1992, Poohlingui is out of the palomino Quarter Horse mare Tardys Peach. Color-wise, she is pure white. White, as in no dark pigment anywhere that can be discerned from weanling registration photos. Registered as a Breeding Stock, Poohlingui has had one foal to date. Born in 1996, and sired by Doc Jensen, a chestnut Quarter Horse son of Doc Bar, that foal is a palomino overo. Doc Jensen has sired no other registered cropout Paints, so it appears probable that Poohlingui is not a solid white horse, but a predominantly white sabino instead.
A doubly-potent Paint
There are numerous other interesting families of sabinos, such as the one founded by Specks Unreal Luck.
Foaled in 1984, he is sired by Unreal, a cropout sabino, and out of Specks Half N Half, a tobiano. As a sabino tovero, Speck’s production record is impressive. Bred mostly to solid mares, he has sired 104 registered foals. Of these, 96, or 91 percent, are colored. Drawing from his tovero heritage, Speck has sired 37 overos, 47 tobianos and 12 toveros. His sabino genetics have kicked in to enable him to sire 41 red roans. With this kind of genetic variety, surely Specks Unreal Luck represents one of the most intriguing potential genetic studies available. As do other sabino families.
Same song, different verse
Thirteenth Verse, is a 1988 red roan sabino mare. A Superior Amateur and Open Halter Horse, Thirteenth Verse was sired by Versa Star and is out of Spice Is Nice. To date, Thirteenth Verse has produced five foals. Of these, four are colored, including two that were sired by Quarter Horses. All four of Thirteenth Verse’s colored foals exhibit both the leg and face markings generally associated with the sabino pattern, and the sharper-edged side and neck spots often seen on calico overos. Does this point to the possibility that the sabino pattern can be likened to a path that branches off in one direction to produce the speckled roan pattern, and forks off in another to produce the more sharply-defined calico pattern? Only more research will tell.
To provide a more-detailed view on the genetic makeup of the sabino, Dr. Phillip Sponenberg, Professor of Pathology and Genetics at the Virginia-Maryland Regional College of Veterinary Medicine was asked to study the production records of several contemporary sabino stallions.
Dr. Sponenberg’s observations are as follows:
A SABINO CASE IN POINT
By D. Phillip Sponenberg, DVM, PhD
Let me begin by stating that the sabino pattern is interesting for several reasons, not the least of which is the subtle and fascinating array of variants that the pattern can take. Sabinos range from quite solid, to very roaned or speckled, to very patched, and everything in between. Nearly all sabinos have white legs, a great deal of white on the head and white areas on the belly. These characteristics help separate the sabinos from the more familiar tobianos and frame overos.The sabino pattern seems to be quite different from the other Paint patterns—tobiano and frame—in the manner in which it is inherited. Tobiano and frame overo are both caused by single genes. Horses either have the gene and are spotted, or don’t have the gene and therefore lack the pattern. With these two patterns there are two fundamental questions for each horse. Question one is, “Is the pattern present or not?” Question two is, “If present, how extensive is the pattern?” These two questions sort all horses into various groups and are important for understanding how the pattern is transmitted from generation to generation. Some foals get the gene, and the pattern, and can then either express a great deal of white or relatively little white. Other foals fail to get the gene, as well as the pattern, from the parent, and therefore make the question of “how much white?” meaningless. The only exception to the passage of these genes is the homozygous tobiano horse, which transmit’s the tobiano gene to all its offspring. The “either/or” question seems not to pertain to the sabino pattern. The only question with it seems to be “how much?” Stated another way, it appears to be simply an extension of the usual white leg and face marks on horses. At one end of the sabino pattern are the basically solid-colored horses, with the white markings just beginning to creep up the legs and jaw. At the other end are the predominantly-white horses. In my book, Equine Color Genetics, published in 1996 by Iowa State University Press, I stated that the sabino allele (SB2) behaves in many cases as though it, too, is a single gene. The sabino production records that have recently been made available to me now strongly suggest that the pattern is polygenic. This means that it comes about as the result of the action of several different genes, each of which make a small contribution to the overall pattern. Minimally-white sabinos simply have fewer of these genes than do maximally-white sabinos. The production records of sabinos strongly supports this theory. Whiter sabinos are more dominant producers of color than the more solid-colored ones. An important observation to make at this point has to do with the apparent difference between maximally-white sabinos and lethal whites. There seems to be strong evidence to support the generally subscribed- to theory that sabinos by themselves, no matter how white they are, produce few, if any, lethal white foals. The progeny of very pale sabinos, such as Puchilingui and Heath Bar None, run the whole range from mostly-solid horses with one or two low socks and maybe a small star, to very white medicine hats. Most of their get, however, tend to be more toward the spotted end of the range, with the highly-desirable body spots, splashes and roan areas typical of the pattern. Bred to 34 Quarter Horse mares, Heath Bar None sired 30 obvious sabinos. This is an 88 percent color ratio and can be explained only by several genes working rather than a single one. A single gene would have resulted in the familiar 50:50 ratio, or maybe 75:25 in the case of a tovero. White on the legs tends to go along with relatively high expression of the sabino pattern. In the case of Heath Bar None, his 34 foals out of the Quarter Horse mares had only four dark legs out of a possible 136. This is remarkable, and the suggestion here is that mating sabinos to Quarter Horse mares with a great deal of white on their legs will probably contribute to an even higher percentage of spotted foals. Clydesdale breeders have been learning to manipulate the sabino pattern for years. They prefer the lower and middle range of expression, so they usually mate horses with four white feet to those with at least one dark foot. That way they are reasonably assured of lots of white on the legs, maybe some patches and roan on the body, but not much more white than that. The take-home message on the sabino pattern is that it can be manipulated just like mixing paint! Foals produced from darker sabinos are likely to slip by undetected until mated just right. This is where many of the Quarter Horse and Thoroughbred cropouts come from. Horses from the medium range of sabino expression are likely to produce the entire range of sabinos, and very white sabinos will lighten and brighten up the foals from virtually every color of mare. In closing, I wish to make several extremely critical points. First of all, as I stated in my book, the sabino pattern is confusing and has been poorly studied. I, in no way, intend for my preliminary study of Heath Bar None’s production record to be misconstrued as an end-all assessment of the sabino pattern. On the opposite side of the coin, the sabino pattern is one of the most interesting and potentially valuable patterns in existence. There are a number of prominent Paint breeders who have been practicing the very theories regarding the pattern that I have placed on the table in this short dissertation. These breeders have, for years, held to the theory that “cropout to cropout” will consistently produce the highest instances of overo color. In the majority of their programs, the cropouts that these individuals are using are minimally-marked sabinos. In many ways, when breeding for overo Paint color, controlling the amount of excess white on the horse is every bit as critical as getting the white in the first place. The sabino pattern, with all its variants, and obvious propensity to throw back to the patterns of previous generations, offers one of the most exciting and potentially rewarding tools to ever be placed at the disposal of the serious Paint breeder. It is a pattern that should, and hopefully will be, studied much more intensely in the future.
The White Markings Genes
And variations thereof
Horse Genetics by Ann T. Bowling and Equine Color Genetics by D. Phillip Sponenberg
Spotting and white markings Melanocytes are rather special cells. First they take their embryonic origin from the same part of the embryo and at the same time as the central nervous system (the brain & spinal cord). After the brain and spinal cord are formed these special cells that are left over at the edge of the area of central nervous system formation are called Neural Crest Cells.
These special Neural Crest cells then migrate throughout the body to form the melanocytes of the skin, the adrenal glands, the dentine of the teeth, some of the bones of the base of the skull and the voice box, the cornea of the eye, special sensory cells of the ear and special components of the involuntary nervous system in the viscera.
The genes producing unpigmented white patches on the body do so by interfering either with the total number of neural crest cells produced or with their ability to migrate. In the developing embryo some structures have a stronger attraction for these migrating cells than others and in a sense have a 'priority' on them if they are in short supply. The skin has the lowest priority and this competition for limited numbers of neural crest cells accounts for some of the commonest patterns of distribution of white markings on domestic mammals.
If one of these patches of white skin is taken and transplanted into a dark colored spot on the animal the resulting transplant will remain white since it has no pigment cells. Injuries that damage the melanocytes in an area can also result in white patches due to failure of these cells to regenerate. In riding horses, it is common to see white spots around the withers and back area.
The major series of genes affecting the distribution of melanocytes in mammals are commonly called the "S" or spotting series - alleles that affect the distribution of pigment bearing cells. The "S" series is responsible for blazes and stockings.
TYPICAL WHITE MARKINGS
In horses, however, there are other genes that produce spotting of different kinds, the pinto, piebald or "broken" pattern, including Tobiano, Overo, (including Frame, Sabino, and Splashed White); and the Appaloosa pattern.
And variations thereof:
Frame - Splashed White - Sabino
There are probably at least three variations of the "overo" pattern caused by different genes or gene combinations. Many breeders are participating in research, so hopefully one day, there will be an easier explanation of the patterns and the genes that produce them.
From our research there seems to be the following variations of overos:
These patterns can also be combined.
The Overo Pattern can manifest itself on any coat color