In the heterozygous state, the Sabino coat pattern usually involves a horse having two or more white feet or legs. The white color will often extend up the legs of the horse to the belly in irregular or fragmented patches. These jagged white patches are commonly referred to as barrel spots or belly spots. The head of a Sabino horse is moderately white and commonly has a blaze or white patch that expands the length of the face. The white areas of a Sabino horse lack pigment, both in the hair and skin.
Whereas other white genes cause more defined and uniform patterns which are easily recognisable, Sabino is a term often put to use for more minimal white areas of a horse which can occur in a wider variety of areas. One common defining feature of Sabino markings tends to be the 'roaning' around the edges of the white markings. This is where the 'border' of the white markings intermix with the horse's base color, and where white hairs start to blend with the darker surrounding coat. This is separate to the roaning gene, which has a similar effect and is often associated with Sabino.
Similarly to frame Overo, Sabino seems to work in a dosage effect. Horses which carry a single inherited copy of the gene will display the broken Sabino markings and possibly only a small amount of white. A horse that carries two inherited copies of the Sabino gene (homozygous) will be almost pure white in appearance. Unlike frame Overo, there is no life-threatening condition attached to the pattern.
The sabino-1 test is proven to determine a gene mutation linked to the Sabino1 coat pattern. The test determines whether a horse is negative, heterozygous or homozygous, for the Sabino 1 mutation.
Animal Genetics offers DNA testing for the mutation linked to Sabino1. The genetic test verifies the presence of the Sabino1 mutation and presents results as one of the following:
|Sb1/Sb1||Homozygous||Maximal Sabino. Horse inherited two copies of the dominant Sabino1 mutation and will always pass 1 copy of Sabino to foals. Homozygous Sabino horses are almost pure white in appearance.|
|n/Sb1||Heterozygous||Positive for one copy of the Sabino1 gene mutation, carrier of a single inherited copy of Sabino. White coat pattern present. Horse's base color may be modified to varying degrees by the Sabino markings.|
|n/n||Negative||Horse can be considered a non-Sabino1 horse.|