Splashed white is a variable white spotting pattern characterized by a large blaze, extended white markings on legs, variable white spotting on belly, pink skin and often blue eyes. In other cases, the unpigmented areas are quite small and cannot be distinguished from horses with other more subtle depigmentation phenotypes. Splashed white horses are sometimes deaf, however most splashed white horses are not deaf. Hearing loss is due to the death of the necessary hair cells, caused by the absence of melanocytes in the inner ear. Although the majority of splash horses have pigment around the outside of the ear, the pigment must occur in the inner ear to prevent hearing loss. There are several different mutations identified that are associated with splashed white patterns. The Coat White Spotting 1 test (P512) tests for the mutation known as SW1 in the MITF gene. This test detects two variants (alleles). The allele SW1 is dominant. One or two copies of the SW1 allele result in splashed white. The allele N is recessive and does not have an effect on the basic colour.
The Coat Colour White Spotting 1 test encloses the following results, in this scheme the results of the Coat Colour White Spotting 1 test are shown in combination with the possible results for the tests that determine the basic Coat Colour (Coat Colour Chestnut and Coat Colour Agouti test):
|
Result White Spotting 1 |
Result Chestnut + Agouti |
Coat Colour |
Description |
|---|---|---|---|
|
N/N |
e/e + A/A, A/a or a/a
|
Chestnut, Sorrel
|
Not Splashed White. The basic colour chestnut/sorrel is not modified unless modified by other colour modifying genes. It can only pass on allele N to its offspring. |
|
N/N |
E/E or E/e + A/A or A/a |
Bay, Brown |
Not Splashed White The basic colour bay/brown is not modified unless modified by other colour modifying genes. It can only pass on allele N to its offspring. |
|
N/N |
E/E or E/e + a/a |
Black |
Not Splashed White. The basic colour black is not modified unless modified by other colour modifying genes. It can only pass on allele N to its offspring. |
|
N/SW1 |
e/e + A/A, A/a or a/a
|
Chestnut/sorrel with Splashed White pattern |
Splashed White pattern. One copy of the SW1 allele. The horse will display some degree of white spotting but the specific pattern cannot be predicted, unless modified by other colour modifying genes. It can pass on either allele N or SW1 to its offspring. |
|
N/SW1 |
E/E or E/e + A/A or A/a |
Brown/bay with Splashed White pattern |
Splashed White pattern. One copy of the SW1 allele. The horse will display some degree of white spotting but the specific pattern cannot be predicted, unless modified by other colour modifying genes. It can pass on either allele N or SW1 to its offspring. |
|
N/SW1 |
E/E or E/e + a/a |
Black with Splashed White pattern |
Splashed White pattern. One copy of the SW1 allele. The horse will display some degree of white spotting but the specific pattern cannot be predicted, unless modified by other colour modifying genes. It can pass on either allele N or SW1 to its offspring. |
|
SW1/SW1 |
e/e + A/A, A/a or a/a |
Chestnut/sorrel with Splashed White pattern |
Splashed White pattern. Two copies of the SW1 allele. The horse will display some degree of white spotting but the specific pattern cannot be predicted, unless modified by other colour modifying genes. It can only pass on allele SW1 to its offspring. |
|
SW1/SW1 |
E/E or E/e + A/A or A/a |
Brown/bay with Splashed White pattern |
Splashed White pattern. Two copies of the SW1 allele. The horse will display some degree of white spotting but the specific pattern cannot be predicted, unless modified by other colour modifying genes. It can only pass on allele SW1 to its offspring. |
|
SW1/SW1 |
E/E or E/e + a/a |
Black with Splashed White pattern |
Splashed White pattern. Two copies of the SW1 allele. The horse will display some degree of white spotting but the specific pattern cannot be predicted, unless modified by other colour modifying genes. It can only pass on allele SW1 to its offspring. |
