Silver (Z), also known as silver dapple, chocolate, or taffy, is a dilution that dilutes black. The silver dilution mutation is on the PMEL17 gene. Silver is dominant, meaning it cannot skip generations. Since silver can only dilute black it has no effect chestnut and thus can appear to skip generations via chestnut. Silvers can range in shade based upon their base color and other dilutions/modifiers. Silver generally lightens the points so they have flaxen manes and/or tails, but that is not a requirement. Black silvers are often described as odd looking chestnuts. Bay silvers often have legs that are not quite black. Silvers can also go through many shade changes throughout their lifetime. There is a test available for silver.
Many silvers are mistaken for chestnuts. In the absence of testing; a black based offspring from seemingly chestnut parents indicates that one parent is a silver instead of a chestnut. Surfer Dude (information and photos below) was discovered to be a silver via this method. Similarly, the silver offspring of a chestnut parent and a non-silver black based parent indicates that the chestnut parent is carrying silver.
Multiple Congenital Ocular Anomalies (MCOA) is a genetic disorder linked to silver. Heterozygous horses are not affected but homozygous silver horses are. MOCA affected horses can have multiple abnormalities of the eye including cysts, cloudy eyes, abnormal lens positions, and pop eyes. Horses with MOCA often have impaired vision and difficulties in adapting to changing light conditions. Silver to silver breedings are not recommended. The Wild Horse Dilemma by Bonnie Gruenberg stated that a silver stallion from Shackleford Banks herd tested positive for MOCA.
The earliest photographic evidence of silver in Chincoteagues is a bay silver named Starlight whom Misty rejected as a mate in the late 1950's. Starlight's photograph appears in the Pictorial Life Story of Misty. An article in the San Francisco Chronicle from 1893 described a Chincoteague Pony that sounds a great deal like a silver, "His coat is a beautiful shade of red, lighter than bay and almost a sorrel. The mane and tails are strikingly conspicuous, being a soft, creamy, white suggestive of silky Augora wool."
Classic Roan (RO), also known as True Roan or Dark Headed Roan, is the most well known type of roan. Classic roan is dominant and thus cannot skip generations. The head and points of a classic roan are not roaned and retain the pony's color. Any color can be roan as roan puts itself over the pony's color. Roans often go through seasonal changes and some roans darken with age. Foals will usually not appear to be roan until they are several months old. Roans often develop patches of solid hair where there has been a scratch or injury, these are known as corn spots.
Another type of roan is Frosty Roan. The mane and tail of frosty roans are mixed with white hairs and some of have white hairs on the face. It is not known if Frosty Roan is a different mutation from classic roan, if it is a variant of classic roan, or if it is the result of an unknown modifier.
The mutation for roan has not been identified, however it is known which chromosome roan resides on. A zygosity test is available which can determine whether a roan is homozygous or not.
A type of roan was briefly found in the Chincoteague Pony, it may have been classic roan or a type of sabino roan. The last known roan Chincoteague died 2008, the feral mare Strawberry Lady. One source stated that a chestnut roan stallion from Farnley Farm was sent to Chincoteague for three years and was bred to mares and that is likely how this type of roan was introduced. The last three roans in the feral Virginia herd were all mares: chestnut roan A Touch of Dust, bay roan Rags to Riches, and chestnut roan Strawberry Lady. It also appears to have died out in the Maryland feral herd. This type of roan may however still exist in private hands as the descendant of one of the three mares.
Grey (G) is a modifier that depigments a horse's body color until it reaches near white. Grey is dominant, and thus cannot skip generations. Greys are born a color and through their lifetime "grey out", and subsequently go through many different graying phases. The speed at which a horse greys out varies. Dapple grey, rose, grey, white grey, steel grey, etc. are all names for stages of greying. Fleabitten greys have small dark flecks on a white coat and bloodmarks are a concentration of fleabits. White greys are often mistaken for true white horses. Greys have dark skin and dark eyes. There is a test available for grey.
Grey is currently not found in Chincoteagues. While there has not been conclusive evidence of a grey Chincoteague, the grey Arabian stallion Skowreym was loaned to the Chincoteague Volunteer Fire Department for two years in the 1960's so it is very likely some of his foals were grey. A postcard likely from that era with a picture of probable greys has also been found.
Grey may have also existed in the early days of the breed. A 1891 article in the New York City newspaper The Sun stated that the ponies "are most frequently black, gray, sorrel, or dun." However, Leonard D. Sale wrote in 1896 in The Horse Review of Chicago that, "I have never yet seen a grey, piebald, dun, or yellow purely bred island pony." A 1923 St. Petersburg Times article described the ponies as "bay, gray, dun, black, and sorrel".
Frame (O), also known as frame overo or just overo, is a pinto pattern. Frame is dominant, and thus cannot skip generations, and only exists in heterozygous form. Homozygous frames suffer from Overo Lethal White Syndrome (OLWS) and are known as Lethal Whites; such foals are born all white and die soon after birth due to an incomplete lower colon. Due to OWLS two frames should never be bred together. Frames generally have dark legs, the white is concentrated on the side of the pony, and have a white face. There is a test available for frame, the same which tests for OLWS.
Frame appears to have existed in the wild herd at some point in the past. It is no longer present in Chincoteagues. It likely would have been introduced through Mustang outcrossing.