Description:  The gene for merle occurs in many dog breeds but is only recognized as an FCI standard in some breeds. Recognized breeds with merle patterns are Australian Shepherd, Border Collie, Dachshund, Great Dane, Louisiana Leopard, Cardigan Welsh Corgi, etc. A black merle dog is called blue merle and a brown merle dog is called red merle. Light merle spots are irregularly distributed over the body. The merle-allele is a SINE insertion in PMEL (SILV) gene, which can be of various lengths, due to its retrotransposomal origin. Normal allele – m is without merle (non-merle); M – merle allele, insertion include a polyT sequence (or polyA-tail), the longer the sequence is, the more significant the merle phenotype is. Results according to the article Murphy et al. (2018):

Mc – cryptic merle (length of polyT sequence ca. 25-62 T);

Ma or Md – atypical or dilution (length of polyT sequence ca. 63-73 T)

M – merle (length of polyT sequence ca. 74-85 T);

Mh – harlequin (length of polyT sequence ca. 86 and more T)

The dog can be merle mosaic, ie. It can carry several types of merle alleles in its cells. Intergenerationally, it may lead to shortening or expansion of the merle allele. In general, it is not appropriate to mate dogs with merle alleles together because of potential health risks

Here is a comparison between Murphy’s way of alleles description and that of Langevin et al.

The table can be downloaded in pdf here

Both methods are available according to the customer’s choice.


Inheritance: incomplete dominant trait


Mutation: SINE insertion in PMEL (before SILV) gene  with various length


Sample: EDTA whole blood (1.0 ml) or 2 buccal brushes. For official purposes, the confirmation of the dog’s identity by Veterinarian is recommended.


The analysis is suitable for the following breeds: Australian Shepherd, Border Collie, Dachshund, Great Dane, Louisiana Leopard, Cardigan Welsh Corgi


Notes: according to the article Murphy, S.C., Evans, J.M., Tsai, K.L. et al. Length variations within the Merle retrotransposon of canine PMEL: correlating genotype with phenotype. Mobile DNA 9, 26 (2018).