Homozygous Merles

Homozygous merles or double merles may only result when a merle is bred to another merle and the puppy receives 2 copies of the merle gene; 1 from each parent.   It is very important to note that although a dog may visually be a none merle, it is still possible for it to genetically be a merle.  Homozygous merles will not have any health risks associated with merle to merle breeding, if the genetic merle lengths of their parents are compatible.  This is DNA testable through M Locus and must include merle length.

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Homozygous merles with incompatible merle lengths usually have excessive white coloration and may also be born blind, deaf, disfigured, and with partial or missing eyes and/or organs.  These puppies are often destroyed immediately after birth due to the high risk of impending health problems.  This breed detriment is completely preventable through DNA testing and responsible breeding.

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Not to be confused with homozygous merles, pattern whites have excessive and/or unacceptable white coloration due to whitehead and/or piebald genetics. 

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Piebald is DNA testable through S Locus, whitehead is not currently testable.

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Extra attention should be given to loss of coloration surrounding the eyes and ears.  This loss of pigment is directly related to a heightened risk of deafness.  

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Hartspride does not breed incompatible merle to merle and only breeds dogs with acceptable and/or minimal white.  

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For more information regarding homozygous and pattern whites please click the link below:

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https://www.australian-shepherd-lovers.com/lethal-white.html