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Silver ( Dapple ) Coat Colour Dilution / MCOA
Test number: 8213 (this test number replaces the old 8154H)
Gene: PMEL17
Price: £ 48.00 (including VAT)
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Description |
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Silver Dilution and Its Association with Multiple Congenital Ocular Anomalies (MCOA)
The silver dilution is a genetic variant that affects black and bay horses, lightening their manes and tails to a flaxen or silver gray. While primarily a coat color modification, silver dilution is also linked to Multiple Congenital Ocular Anomalies (MCOA), an inherited eye condition that can lead to structural abnormalities.
Silver Dilution and Its Effects
The silver gene is responsible for diluting black pigmentation, altering coat color in affected horses:
- Black-based horses develop chocolate coats, often with dappling, while their mane and tail lighten to silver gray.
- Bay-based horses exhibit red silvers or bay silvers, where dark points, such as the mane and tail, take on a flaxen hue.
- Chestnut horses do not show visible effects but may still carry the gene and be affected by MCOA.
The silver gene follows an autosomal-dominant inheritance pattern, meaning that even a single copy is sufficient to produce coat dilution.
Genetic Link to MCOA
Horses carrying the silver dilution gene—whether visibly affected or not—may develop ocular anomalies, including cysts, corneal enlargement, and abnormalities in the retina and iris. The severity of MCOA depends on the genetic makeup:
Genotypic Variations
- N/N (Non-carrier): Horses with this genotype do not exhibit silver dilution or MCOA and cannot pass the silver gene to offspring.
- Z/N (Single Silver Gene Carrier): These horses show silver dilution and have a 50% chance of passing the gene to foals. Their form of MCOA is typically mild.
- Z/Z (Double Silver Gene Carrier): Horses with this genotype will always pass the silver gene to their offspring and often exhibit a more severe form of MCOA.
- Chestnut horses with one or two copies: These do not show coat dilution but remain susceptible to ocular abnormalities related to MCOA.
Breeding Considerations
Because the silver gene is linked to MCOA, genetic testing is recommended to identify carriers and predict inheritance risks. The Silver (Dapple) gene in horses is genetically related to the Merle phenotype in dogs, both associated with pigment dilution and potential eye abnormalities. Breeding two silver horses together increases the likelihood of more severe MCOA cases.
Conclusion
The silver dilution gene influences coat color and is also associated with MCOA, a congenital eye disorder. Genetic screening can help manage breeding risks and maintain the health of affected horses.
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Sample Requirements |
Hair Sample from mane with roots (approx 30 hairs) or 1 ml whole blood in EDTA tube.
How to obtain a viable hair sample
Pull around 30 hairs from the mane of the horse with the roots (in faols hair from the tail maybe taken). Wrap the hairs around your finger or a comb, as close as possible to the skin to ensure you obtain the hair roots. Keep dry, put in a bag, label the bag with the horse name, test (s) required. Place in an envelope and send back to us together with the order form. Broken or cut off hair will not be accepted.
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Price
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£ 48.00 (including VAT)
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| See also: |
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Coat Colour chestnut (Red Factor)
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Tobiano (Tobiano Spttings) / (Paint, Pinto, Tinker)
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Greying
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Coat Colour Champagne
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Sabino -1
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Dominant white (GQ Santana dominant white W5, W10, W13, W20 and W22)*
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Dun Zygosity
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Leopard complex
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Pearl
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Roan Zygosity*
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Splashed white (SW1 , SW2 , SW3 and SW4)
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Coat Colour black / Bay (Agouti)
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Camarillo White - W4
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Curly Coat
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Coat colour Sunshire Dilution / Dilute
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Mushroom
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Brindle 1 (BR1) (irregular vertical striped pattern )
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Splashed white (SW5 - SW8) *
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Bundle: Basic Coat Colour (Agouti + Red Factor / Chestnut )
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Bundle: Dilutions Coat Colour (Cream, Champagne, Dun Zygosity, Silver, Pearl)
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Bundle: White Patterns Coat Colour (LWO, Leopard complex, Appaloosa Pattern, Tobiano, Splashed White, Sabino)
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Snowdrop dilution
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Incontinentia Pigmenti (IP)
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Appaloosa Pattern 1 (PATN-1) *
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Coat Colour Cream / Dilution / Dilute
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