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Silver dilution (Dapple)

    DNA test The genetic test verifies the presence of the Silver coat dilution modifier. The Silver genetic variant is associated with...

    £38.00

      Sample RequirementsSample Requirements

      30 to 40 - hair roots - envelope or 5 mL - blood - K3 EDTA tube

      Send your sample by regular mail or express delivery to:

      Equigerminal Lab HIESE
      Rua da Quinta do Sobreiro Nº25
      3230-343 Penela, Portugal

      Turnaround TimeTurnaround Time

      2 to 5  working days

      About the testAbout the test

      This DNA test detects the Silver (Z) coat colour dilution variant, a dominant genetic trait that dilutes black pigment in horses. In several breeds, the Silver variant is also associated with Multiple Congenital Ocular Anomalies (MCOA), making this test valuable for both coat colour prediction and breeding management.

      Why test?Why test?

      Testing is recommended to:

      • Identify horses carrying the Silver (Z) variant.
      • Predict Silver coat colour inheritance.
      • Assess the genetic risk of Multiple Congenital Ocular Anomalies (MCOA).
      • Support responsible breeding decisions.
      • Prevent mating combinations that may increase the risk of severe ocular abnormalities.
      How it worksHow it works

      🛒 Purchase the Test: Select and buy the test online.

      📧 Receive Instructions: After payment confirmation, receive instructions for sample collection.

      ✨ Sample Collection: Your veterinarian collects hair roots or a blood sample.

      📄 Download Submission Form: Download the printable submission form.

      📮 Send Samples: Send your samples by regular mail or express delivery to:

      Equigerminal Lab HIESE
      Rua da Quinta do Sobreiro Nº25
      3230-343 Penela, Portugal

      📄 Receive Results: Get your result certificate by email.

      Clinical signsClinical signs

      Horses carrying the Silver variant may develop ocular abnormalities associated with MCOA, including:

      • Iris cysts
      • Corneal abnormalities
      • Cataracts
      • Abnormal pupil shape
      • Reduced vision in severe cases

      Clinical severity is generally greater in homozygous (Z/Z) horses than in heterozygous (N/Z) horses.

      TransmissionTransmission

      The Silver variant is inherited as an autosomal dominant trait. Horses carrying one copy (N/Z) have a 50% chance of passing the variant to their offspring, while homozygous horses (Z/Z) will transmit the variant to 100% of their progeny.

      PreventionPrevention

      There is no treatment to prevent inheritance of the Silver variant. Genetic testing before breeding allows informed mating decisions and helps reduce the likelihood of producing offspring at increased risk of severe MCOA.

      ResultsResults

      The DNA test verifies the presence of the silver gene and presents results as one of the following:

      • N/ – Negative for Silver - No evidence of the genetic variant for Silver. No risk to develop Multiple Congenital Ocular Abnormalities (MCOA) associated to Silver.
      • Z/N - Heterozygous for Silver - The Black and Bay basic coat colour will be diluted by Silver. Black-based horses will be chocolate with flaxen mane and tail. Bay-based horses will have pigment on lower legs lightened and flaxen mane and tail. No effect on chestnut color. Moderate risk to develop MCOA.
      • Z/ – Homozygous for Silver - Two copies of altered sequence detected. Black-based horses will be chocolate with flaxen mane and tail. Bay-based horses will have pigment on lower legs lightened and flaxen mane and tail. No effect on chestnut color, but will pass the variant on to 100% of offspring.  Higher risk to develop severe MCOA.
      Additional informationAdditional information

      The Silver dilution affects only black pigment (eumelanin) and therefore modifies the appearance of black and bay horses, while chestnut horses (e/e) can carry the variant without showing any visible coat colour change.

      The mutation has been identified in several breeds, including Rocky Mountain Horses, Icelandic Horses, Quarter Horses, Morgans, Shetland Ponies, Miniature Horses, and others.

      References:

      Brunberg, E., Andersson, L., Cothran, G., Sandberg, K., Mikko, S., Lindgren, G.: A missense mutation in PMEL17 is associated with the silver coat color in the horse. BMC Genetics 7:46, 2006.

      Andersson, L.S., Wilbe, M., Viluma, A., Cothran, G., Ekesten, B., Ewart, S., Lindgren, G.: Equine Multiple Congenital Ocular Anomalies and Silver Coat Colour Result from the Pleiotropic Effects of Mutant PMEL. PLoS One 8:e75639, 2013.

      FAQsFAQs

      Which horses should be tested?

      Testing is recommended for horses from breeds known to carry the Silver variant or when planning breeding involving Silver-coloured horses.

      Does the Silver gene affect all coat colours?

      No. The Silver variant only dilutes black pigment. Chestnut horses can carry the mutation without showing any visible coat colour change.

      Does every Silver horse develop eye disease?

      Not necessarily. Horses carrying the Silver variant have an increased genetic risk of Multiple Congenital Ocular Anomalies (MCOA), with homozygous horses generally being more severely affected.

      Which samples are accepted?

      The test can be performed using 30–40 hair roots or 5 mL of blood collected in a K3 EDTA tube.

      When will I receive my results?

      Results are available within 2 to 5 working days after sample arrival at the laboratory.

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