Night blindness / Appaloosa pattern / Leopard complex (TRPM1-related) - Horse

Night blindness and Appaloosa patterning

This genetic test detects the TRPM1-related LP allele for the Appaloosa pattern, also known as leopard complex, leopard spotting or LP. This allele influences the typical white coat patterning, mottled skin, striped hooves and visible sclera seen in Appaloosa-like coat patterns.

The LP allele acts as incomplete dominant for coat patterning: one copy can already produce leopard complex traits. Horses with two copies usually show stronger pattern expression and also develop congenital stationary night blindness, abbreviated CSNB. CSNB reduces vision in dim light and darkness from a young age.

Practical value of this test

• N/N: no LP allele detected.
• N/LP: one copy of LP; the horse can show Appaloosa/leopard complex traits and pass the allele on.
• LP/LP: two copies of LP; this genotype causes CSNB and usually gives clear LP pattern expression.

The result helps breeders plan Appaloosa patterning deliberately while managing the risk of LP/LP offspring with night blindness.