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exploring the color genetics of equines

bloody marks / 10

ISSUE ONE / DEC. 2012


CONTENTS TEST FOR SPLASH / 3 splashed white genome identified OVERO LETHAL WHITE / 4 color that can kill BLOODYMARKS /8 a gray matter THE PASO FINO / 10 A THIN LINE / 12 dorsal stripe or countershading

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vents

RHA Lotto Locomotion

TEST FOR SPLASH

I

n January of this year, the latest research has finally uncovered the mutation responsible for the Splashed White phenotype - or, in this case, three separate mutations: SW1, SW2 and SW3. UC Davis is now offering a test for Splashed White for $25. Tests have already located SW1 in the Quarter Horse, Paint, Trakehner, Miniature Horse, Shetland Pony and Icelandic Horse breeds. Unlike Frame Overo, SW1 has not been found to be lethal in its homozygous state (SW1/SW1.) However, SW2 and, the rare, SW3 (which has only been found in certain lines of Quarter Horses and Paints) is thought to be homozygously lethal. UC Davis discourages the breeding of two horses known to carry SW2 or SW3. For more information visit: vgl.ucdavis.edu/services/horse/splashedwhite.php

Reported results Mutation not found:

N/N

Heterozygous for Splash:

N/SW1, N/SW2, N/SW3

Homozygous for Splash:

SW1/SW1

Possibly lethal:

SW2/SW2, SW3/SW3 DEC. 2012 / 3


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e t n e s h t a “A deention.” prev

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WHITE T

he birth o f a foal sho uld be a jo ow n e r a n yo u s o c c a d m a re . M sion for bo o n t h th s a re s p e n t perfect st searching ud with p for the erfect blo match for odlines th the mare’s a t is the bes s t re n g t h s t h e r e wa s t a n d we a k the foresig n e s s e s h . t M t o choose t ay b e genes hop he stud w ing to pro it h d t u h ce a foal w e right o r p a t te r n ith a spec . Extensiv if ic c e o finances a at color a n d e ve n re investe more for m d fo r stud fees a re c a re w months fo hile waitin r the per g e leven mor fect foal t h a p py o u t e o arrive. come is n U n fo r t o u t n a a lways the tely, a watching case. A few the foal e h o m u rs after erge into a p p a re n t the world that som , it e becomes thing is h t re a s u re d orribly w progeny. I r o n g t begins w with the t h a t g ro w ith the sy s m o re s m p t om of coli e ve r a s t diagnosis c he hours from the p a s s . A v e p t ositive erinarian White Syn confirms d ro m e . T h O v e e r o Lethal re is no cu within a re ; t h e p ro few days g n o s is – euthana is death the cours sia recom e o f a ye a m e n d e d . O ve r r, preciou emotions s re s o u rc h a ve b e e n e s a nd person spent on that is ent al o n e d re a d irely avoid fu l r e a s u b lt; one le. Overo L is a death ethal Whit s e n te n c e e Sy n d r o m with only e o n e c u re – preventio n.


B

y all appearances, a foal born with Overo Lethal White Syndrome looks healthy, and for the first few hours of his life, he is just like every normal foal; he takes his first steps, nurses without help, and frolics like any other newborn. Unfortunately, the nerves of his bowel never formed properly. Because of a Lethal White foal this malformation, the foal has no urge or ability to defecate. The first outward signs of complications usually occurs within a few hours. Within the first twelve hours of the foal’s life, he will begin to exhibit the symptoms of colic. If the foal is not euthanized, around seventy-two hours, a build-up of feces eventually leads to the toxic poisoning and inevitable death of the foal. A mutated Frame Overo gene is responsible for Overo Lethal White Syndrome. With one copy of the gene, its heterozygous state, it has no effect on the health of the horse and merely is carried and/or passed on. The only possible way for a foal to be a Lethal White is if both parents carry and pass the lethal allele. Yet, the mutated allele only passes from parent to foal a percentage of the time. When a lethal carrier is bred to a noncarrier horse there is only a fifty percent chance that the foal will also be a carrier. Likewise, when

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two Lethal White carrier horses are bred together there is only a twenty-five percent chance the foal will be Lethal White. Fortunately, prevention is extremely simple, although, many breeders are ignorant of the disease; sometimes, it is ignored by some breeders altogether. Some breeders even believe that the twentyfive chance of producing a Lethal White foal is worth the possibility of producing a non-Lethal White foal from a highly desired pairing. The non-Lethal White offspring of two amazing, Lethal carriers is considered to be much more valuable than the risk and cost of producing a Lethal White foal. Being ignorant of the disease entirely and doing nothing to prevent it is one thing, but knowingly producing a possibly inviable foal is usually looked on as a cruel, unnecessary action. However, being willingly ignorant about the genetic condition of a horse before it is bred is, essentially, just as cruel. It is responsible horse ownership and breeding to get a full range of checks done on the horse before any breeding is done. There are a myriad of genetic problems, not just Overo Lethal White Syndrome, that could be passed on to the foal with the wrong choice of parentage.


LETHAL WHITE The surest way to give a foal the best start possible is proper genetic testing of both sire and dam. To have a zero percent chance of a Lethal White foal, Lethal White carriers should never be bred together. Thankfully, a genetic test to assure if a horse is a carrier or not is well within reach. For only twenty-five dollars, a horse can be tested to see if it is a carrier of the mutated allele responsible for Lethal White. To be as cautious as possible, all horses that have even just a suspected Overo lineage should be tested before being bred regardless of whether they have any Overo markings themselves. As stated above, it is possible for a solid horse to be a carrier as well. It is impossible to be too careful or responsible when breeding. With preventative methods taken, there could be no more Lethal White foals born. With an increased education of the disease, Overo Lethal White Syndrome would become an understood risk of breeding – one easily prevented. The sooner all are educated on this disease and its preventative measures, the better future Overos will have.

e Overo m a r F o n N N/ vero O e m a r F f o r N/O - carrie l White a h t e L o r e v O/O - O

LTD Magic Mans Incognito / solid carrier (N/O)

Dillon Ryan / typical frame carrier (N/O)

:

E D O C C I T E N E E OVERO G

FRAM

CARRIERS

Skip Y Two K Nine / “hidden” frame carrier (N/O)

DEC. 2012 / 7


xpose

A GRAY MATTER

BLOODMARKS

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A

n ancient Arabic legend tells of a powerful Sheik who, after engaging in battle with a rival Sheik, is fatally wounded. The Sheik’s blood stained the shoulders of his faithful, gray mare as she carefully, as to not disturb her master, walked home. The Sheik died from his wounds the same

Bloodmark is the term given for a specific area of a horse’s coat which remains pigmented despite the presence of the gray gene which typically makes a horse rapidly lose all hair pigmentation. Research has realized that these bloodmarks are deactivated areas of a heterozygous gray’s gene (G/g) which allows the pigmentation of the original coat color to remain in specific spots.

night the mare foaled. A colt with markings identical to the blood stains of his dam’s coat was born. Legend states that the Sheik made a deal with the gods to, in remembrance of his mare’s dedication, award the bloody marks to all of her offspring that possessed her courage and ability as a mark of honor.

/ Arabians and Thoroughbreds are the most common breeds to sport these marks, but any gray horse is susceptible. / The name “bloodmark” seems to indicate the marks appear on only the vivid red basecoats of chestnuts and bays, but, in truth, any gray’s basecoat can be a bloodmark.

DEC. 2012 / 9


xpose

THE COLORFUL

PASO FINO T

he versatile breed, the Paso Fino, reflects its Spanish heritage through its proud carriage, grace and elegance. Modern care and selective breeding have enhanced its beauty, refinement and wellproportioned conformation that conveys strength and power without any extreme muscling. The Paso Fino is born with a gait unique to the breed. The gait, being totally bay sabino roan

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natural, does not exhibit the catapulting or exaggerated leg action of some manmade gaits; rather the movements are smooth, rhythmic and purposeful. The Paso Fino is truly a versatile breed that comes in a multitude of shapes, ranging from stocky to streamlined, and heights, ranging from 13hh to 16hh. The Paso Fino also excites with its vibrant

Platanera Dorada / palomino

coat color possibilities. The breed comes in the greater majority of the equine coat colors, dilutions, modifiers and patterns possible with no breed restrictions on white markings. The Paso Fino breed, with its definite but controlled spirit, natural gait and presence, and responsive attitude, the Paso Fino is indeed, a rare and desirable equine partner.

flaxen chestnut sabino

BASE black, chestnut

MODIFIERS dun, silver, grey, roan

DILUTIONS agouti, cream

PATTERNS tobiano, sabino, rabicano, splash


Cale’s Helado Oro / silver bay DEC. 2012 / 11


VISUAL IDENTITY

FLAG

COLORS RGB: 255, 242, 0

CMYK: 0, 0, 100, 0 HEX: #FFF200

RGB: 0, 0, 0

CMYK: 0, 0, 0, 100 HEX: #000000

DEPARTMENT HEAD vents xpose valution

FOLIOS

HEADER SUBHEAD

left right

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TitilliumText22L / thin / 72

TitilliumText22L / medium / 36

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Cambria / regular / 12/17/20

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TitilliumText22L / regular / 9

E/e Dec. 2012  
E/e Dec. 2012  

Exploring the color genetics of equines.

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