Preface:   The following article appeared in the March 1976 Appaloosa News. A related article by Mr. Hatley is also posted at this web site, "Why Appaloosas Should Not Be Crossed With Non-Appaloosa Roans and Grays." At the start of this article, Mr. Hatley writes about rules/resolutions from 1975/1976. That was more than 25 years ago. Rules have changed.  (Thanks to Shelby Snorek for help with this article.)

Joe Daniels
January 2002

At the June 1975 Appaloosa Horse Club board meeting, the Board passed a resolution to discontinue issuing pedigree certificates to grays and non-Appaloosa roans starting January 1, 1976. At the November 1975 board meeting, the Board passed a resolution to not accept for registry the result of mating a registered Appaloosa with a registered gray or non-Appaloosa roan of any of the breeds that are presently accepted for cross breeding.

Both rules will decrease the introduction of both gray and non-Appaloosa roan into the Appaloosa. The introduction of gray into the Appaloosa creates three serious problems. The first and most obvious is the fact that an Appaloosa with graying tends to lose its contrast and in a short time becomes a white horse. Most people who like Appaloosas also like their distinctive coat markings and dislike seeing a well-marked Appaloosa become a white horse in a short period of time. Even though less than 10% of Appaloosas presently carry graying, we often hear from disenchanted new owners who unknowlingly bought a weanling with beautiful, big spots only to have the spots disappear and have a white horse in two to four years. The disillusioned new owner who had his first Appaloosa turn white is quick to advise other potential new owners of the fading problem. This is harmful to the Appaloosa industry in general.

Problem number two is the fact that a high percentage of grays develop melanoma. Melanoma is a tumor made up of melanin-pigmented cells. A high percentage of these tumors become malignant. It is often necessary that they be removed, and in some cases they prove fatal.

Problem number three is essentially a recognition problem. Many Appaloosa breeders have trouble distinguishing between an Appaloosa that is developing a roan or spotted coat pattern and a non-Appaloosa gray that is undergoing the graying process. Because of introduction of gray into Appaloosas, the registry receives many applications for non-Appaloosa grays from people who seriously believe the animal is an Appaloosa roan. It is necessary to point out to the applicant that the non-Appaloosa gray does not have Appaloosa characteristics, and this produces a very disappointed owner. If an Appaloosa is crossed with a bay or a chestnut, with no Appaloosa characteristics, the owner is aware that the mating resulted in a non-Appalosa. If a mating is made with a gray and resulting foal does not have Appaloosa characteristics but does have graying, the owner mistakenly believes an Appaloosa has been produced.

Crosses to non-Appaloosa roans result in the same problem has crosses to grays in that people assume that they have an Appaloosa when in reality they have a non-Appaloosa roan. In addition, this particular cross seems to mask out the normal Appaloosa pattern of roan even though the resulting foal had Appaloosa characteristics. The result of an Appaloosa to non-Appaloosa roan mating or an Appaloosa which carries factors for non-Appaloosa roan often has a dark head, and the body will be a uniform shade of roan without the dark area about the frontal bones, elbow, hip, and stifle. The result of this cross tends to eliminate the Appaloosa pattern even though the foal may have Appaloosa characteristics. Examples of the results of these crosses are illustrated in figures 19, 20, and 21 of the pamphlet "Crosses That Will Kill Your Color."

Some owners have difficulty accepting both the genetic facts concerning the breeding of grays and roans and the clinical facts concerning melanoma in grays.

The genetics of gray in horses has been understood by geneticists for at least 45 years. The book entitled THE GENETICS OF THE HORSE, by F.A.E. Crew and A.D. Buchanan Smith published in 1930 spells out the fact that heterozygous gray Gg + Hetrozygous gray Gg results in a 1:2:1 ratio or 1 GG, 2 Gg and 1 gg, or 75 percent grays and 25 percent non-grays. It also lists gray plus non-gray which would be Gg + gg, resulting in a 1:1 ratio or 50 percent grays and 50 percent non-grays.

Castle's work cites in the pamphlet "Crosses That Will Kill Your Color" appeared in the 1948 issue of GENETICS. Castle also discusses gray in a 1954 issue of GENETICS. He states:

"Gray is the name given to a progresssive type of silvering found in the Percheron and in certain other breeds of horses. It results from a dominanat gene G (gray). The coat of a gray horse, like that of a roan, consists of a mixture of white with colored hairs (mostly black) but the white hairs are not present in the first coat, as they are in roans, but only make their appearance in a later coat and subsequently increase until the coat may become practically all white at an age of 4 to 12 years. So this type of silvering is not congenital but progressive, in which two respects it differs from roan."

George Gaylord Simpson in his book HORSES states:

"Grays are usually born dark brown or black. White hairs begin to appear as the animals become older and they may eventually become almost pure white. Some grays breed true and others have mixed color heredity. In the latter case, gray to gray matings produce about three-fourths gray foals and about one-fourth other colors."

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In referring to grays that breed true, he would be referring to matings made between grays that were GG. A majority of grays with this genetic makeup would appear among the Lipizzan as they breed almost pure for grays. The very few non-grays which occur would result from matings that were Gg.

Dr. Ross Christian, geneticist at the University of Idaho in "The Inheritance of Coat Color," printed in HORSEMAN'S SHORT COURSE, states:

"There are two pairs of genes which produce an interspersion of white hairs with colored hairs. First is the gene for gray (G), which is dominant to the non-gray (g) gene; both GG and Gg horses will be gray and gg will be non-gray. Animals carrying the G gene are not born with white hairs and appear to be of solid color. The first white hairs show up with subsequent sheddings so that the animals become much lighter in color. Old gray horses are almost white in color. The gray gene is usually associated with black coat color; however, it may be found in bay and chestnut."

An explanation of the graying gene and a definition of the term "epistatic" which is used in the first paragraph of "Crosses That Will Kill Your Color" is given by Dr. W. Ralph Singleton in his book Elementary Genetics:

"Independent Genes Affecting Coat Color"
"In addition to the five basic genes whose interactions produce the colors just discussed, there are a few genes that seem to produce their effects regardless of the genetic constitution of the five basic genes. In horses, the most important of these are the genes for gray (B) ....

"Epistatic and Hypostatic Genes"
"The genes listed in the preceding paragraphs are sometimes called 'epistatic' genes . . . . According to Bateson, the term epistatic (placed above) is applied to a gene that conceals or masks one or more other genes . . .
"A good example is the gene for gray color in horses. Animals that are Gg or GG develop gray hairs which completely replace the original, whether black, brown, bay, or chestnut. The gene for gray G is prevalent in the Percheron breed of draft horses. Foals are born black and turn gray as the animal becomes several years old. This has given rise to the fallacious theory that all gray horses are black as foals and turn gray later. Actually a foal may be born black, bay, brown, chestnut, sorrel, or even palamino and turn gray later if the gene for G is present. In Welsh ponies, where the gene for G is rather common, this change of color comes at a very early age. Hence it is necessary to record the color of a foal rather early to know the true phenotype, before it is covered or masked by the gene for gray (G).

"The phenotypic expression of G is a gray animal. Gray is not dominant to black, brown, bay, or chestnut, but to its own absence, or non-gray (g). The phenotype expression of the gg genotype is 'no gray hairs.' The gene for G expresses inself regardless of any other gene present. In doing so, it masks or conceals the original color of the animal"

One of the most recent works with information on graying goes further and confirms the fact that graying does mask the Appaloosa pattern by eliminating the pigmented hair. Dr. Jones and Dr. Bogart verify the process of graying in their bood GENETICS OF THE HORSE. They state:

"THE G LOCUS.  The G allele produces the gray horse . . . The recessive allele has no phenotypic effect. . . .

"Gray in horses is dominant to non-gray. Foals with the gray gene (G) are born pigmented but start showing gray with the first shedding of hair. Gray horses show more gray with age and may become completely white in old age. According to Salisbury (1941) animals that are GG tend to gray more rapidly and to become white to a greater extent that Gg gray animals.

"Horses of all colors may be gray but draft horse breeders are more familiar with black gray that occurs in the Percheron. Percheron horses are usually black and the G gene give a black gray. When the gray gene is present in bay horses it gives a red gray and in chestnut colored horses the gray gene results in chestnut gray animals. The gray gene in palaminos will tend to cause them to appear lighter and eventually to appear white as the horse ages. The gray gene can mask the Appaloosa pattern by causing the dark spots on the white background or the dark background in which there are white spots to become light or white.

"As pigment is removed from the hair by the gray gene, it sometimes accumulates in the skin about the anus and in the big gut of the horse. If melanomas develop in the colon or big gut, there can be strangulation which may cause death."

In discussing the unfortunate results of using grays or Appaloosas having the graying gene in a Appaloosa breeding program in APPALOOSA NEWS, we have never mentioned the melanoma problem in grays, and prehaps this should be mentioned. The owner of an Appaloosa with graying not only faces the problem of the horse losing contrast and becoming nearly white, he also faces the strong likelihood of a serious cancer problem. Some years ago in discussing horse colors, Dr. Kenneth White stated, "Gray in horses should not be classed as a color, it should be classed as a disease." In making this statement he was referring to the high incidence of melanoma in gray horses.

The melanoma problem in grays is further confirmed by A.G. Searl in the book COMPARATIVE GENETICS OF COAT COLOUR IN MAMMALS. He states:

"The gray horse may have a wide range of different genotypes, being for instance a bay, black, or chestnut with the additon of G, the factor for progressive silvering. This factor is characteristic of the Percheron and of the Lipizzaner breed.

"Grey G. This is a progressive type of silvering in which the first juvenile coat is solid colour but the second is silvered with white hairs. The number of them gradually increase until the coat is almost complete white, although skin and eyes remain dark. Thus the melanin granules are somehow prevented from passing into the hair. It is interesting to note that G has an unfavourable pleiotropic effect, for grey horses are exceptionally prone to skin cancers, in the form of melanomata (Hadwen, 1931; Cotchin, 1956; Pack et al., 1963). Freckling is common in old white horses and seems to be associated with melanomata, which are particularly common in the perianal region"

Melanoma is discussed at length by D. J.F. Bone in the book EQUINE MEDICINE AND SURGERY. It states:

"Melanoma. Melanomas arise from melanin-forming cells. They may be classed as either benign or malignant. The grade of malignancy is represented by the degree of anaplasia, the number of hyperchromatic nuclei, bisarre forms, and mitotic figures. Lymphocytic in filtration in also considered to be a sign of malignance."

Dr. E.J. Calcott and J.F. Smithcors in PROGRESS IN EQUINE PRACTICE state:

"Both benign and malignant melanomas are very common in gray horses . . . The incidence of melanomas in such animals increases steadily after they become six years of age.":

Drs. Calcott and Smithcors elaborate further in their book EQUINE MEDICINE AND SURGERY. In this, they state:

"Melanoma. These neoplasms are comprised of malanin producing cells, and they usually are referred to as benign or malignant melanomas depending on their behavioral pattern. Though most equine melanomas occur in gray horses, occasionally they are found in horses with other hair color. Approximately 80 percent of gray horses more that 15 years of age have developed clinically recognizable melanomatic growths. It has been suggested that all gray horses eventually would develop melanomas if they lived long enough."

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The members quite clearly made their feelings known toward the white horse in the poll that was conducted concerning regular papers and Breeding Stock papers. Figure F, which was a horse that had turned nearly white from graying, received 301 votes for Regular papers as contrasted with 4,284 for Breeding Stock papers. The 301 to 4,284 corresponds closely to the seven percent of owners who presently own Appaloosas with graying. The breed will benefit from more people placing the longtime benefit of the breed and their customer ahead of any short term financial benefit. Too often I have heard a breeder of an Appaloosa foal with graying gene state, "I need to get this one sold at weaning time." The breeder knows that if the foal was not sold at weaning, it would turn white, and the salability would be greatly reduced.

Since graying is only carried when it is expressed (a horse that is not gray does not carry the graying gene), it could readily be eliminated from the breed by breeders simply discontinuing the use of breeding animals that are gray. The elimination of graying from Appaloosas would be a tremendous benefit to both the breed and all future owners.

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{This article, "Grays and Non-Appaloosa Roans," by George B. Hatley, was originally published in the Appaloosa News, March 1976, Vol 33, No. 3, and is used here by permission.}

Copyright © 1976 Appaloosa Horse Club. All rights reserved.

This article first appeared on the world wide web in January 2002 at URL:   barnlot.tripod.com

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