The Leopard Complex (LP), also known as the Appaloosa spotting pattern, is an incompletely dominant coat colour variant with highly variable expression.

Typical characteristics include:

• Spotted or mottled skin around the eyes, muzzle, genitalia and anus.
• Progressive varnish roaning.
• White spotting with leopard spots in many horses.
  

The amount of white spotting is influenced by additional genetic factors, including the PATN1 patterning gene.

The LP genetic variant is associated with two important inherited conditions:

Equine Recurrent Uveitis (ERU)

ERU is the most common cause of blindness in horses and is characterised by repeated episodes of inflammation inside the eye. Recurrent inflammation may lead to cataracts, glaucoma and permanent vision loss.

Genetic risk follows the pattern:

LP/LP > LP/N > N/N

Congenital Stationary Night Blindness (CSNB)

CSNB affects horses that are homozygous (LP/LP) and results in an inability to see under low-light or dark conditions.

The LP variant is most commonly associated with the Appaloosa breed but is also found in several other breeds, including Knabstrupper, Noriker, Pony of the Americas, British Spotted Pony, American Miniature Horse, Mustang and Tiger Horse.