THE FOLLOWING GENETIC LEVEL COAT COLOR TESTING IS NOW AVAILABLE IN THE GREAT DANE:
(i) HOMOZYGOUS BLACK (i.e carrier status for fawn/brindle); (ii) BLACK vs. BlUE; (iii) BLACK vs. CHOCOLATE (brown), (iv) MASKING GENE (i. e. is a Dane homozygous for mask or not, or even lacking in mask); (v) PIEBALD & PIEBALD CARRIER ("excessive white", i.e. s^p/s^e) , (vi) MERLE (test is available to determine if a Dane has one, two or zero merle genes) & (vii) HARLEQUIN (test to determine if Danes other than Harlequin carry the harle gene). Note there is not yet a commercial test for fawn vs. brindle pattern, nor is there a test currently for the Mantle pattern, but research is ongoing, and using available testing, the existence of genes for these patterns can be inferred.
SOME EXAMPLES OF WHEN SPECIFIC BREEDERS MIGHT WANT TO COLOR TEST (note this list is NOT complete for all possible testing scenarios or every example where a breeder/owner might want to test their Dane(s) for color issues):
(1) OF CONCERN TO FAWN/BRINDLE BREEDERS: blue carrier? (Test for Black vs. Blue)
(2) OF CONCERN TO FAWN/BRINDLE BREEDERS: true for mask? (Test for Masking homozygosity)
(3) OF CONCERN TO BLACK/BLUE BREEDERS: fawn carrier? (Test for Black homozygosity)
(4) OF CONCERN TO BLACK BREEDERS: fawn and/or blue carrier? (Test for Black vs. Blue and/or Black homozygosity)
(5) OF CONCERN TO HARLEQUIN/MANTLE BREEDERS: fawn and/or blue carrier? (Test for Black vs. Blue and/or Black homozygosity)
(6) OF CONCERN TO HARLEQUIN/MANTLE BREEDERS: what is the genotype of this predominately white Dane? (Test for both merle and piebald)
(7) OF CONCERN TO HARLEQUIN/MANTLE BREEDERS: does my Mantle carry piebald and/or harl genes? (Test for harle and/or piebald)
PUNNETT SQUARES OF EXPECTED OUTCOMES IN BREEDING AOAC GREAT DANES ARE AVAILABLE HERE: http://www.chromadane.com/ColorPunnettSquaresDoc.htm
**Please refer to the websites of such companies as Health Gene, Idexx, VetGen. DDC & UCDAVIS for specific information on testing your dogs. Refer also Dr. Schmutz' website on Genetics of Coat Color in Dogs regularly for timely updates.
PIEBALD GENE INFORMATION:
Currently only one company, HEALTH GENE in Canada, offers a commercial test for this recessive form of white spotting (called piebald or excessive white spotting). The piebald gene can produce a dog with extensive white markings (i.e. a white body), but dogs with the Mantle and even "mismarked black" patterns can be piebald carriers. Dogs with two copies of the piebald gene appear largely white and may suffer from deafness in conjunction with, or in complete exclusive to, merle and harl gene And a predominately white Dane can have 0-1-2 piebald genes, 0-1-2 merle genes, and 0-1 harle genes, so testing is especially relevant in these cases to determine true genotype.
MERLE GENE TESTING: Currently only one company, IDEXX in Canada, offers a commercial test for this important gene found in the Harlequin family of Danes. Genetic Harlequins by definition have ONE merle gene as do genetic Merles. White & Merlikin Danes have TWO merle genes. All other Danes are free of this gene. Merle is dominant & so, except for some very rare cases, can be seen. Danes with two merle genes may suffer from deafness & various eye defects, so avoiding the breeding of two parents with merle genes can avoid this outcome.
HARLE GENE TESTING: Currently harle gene testing is only done by Dr. Leigh Anne Clark, the scientist who discovered both the harle & the merle genes. Contact Dr. Clark directly if wanting to test for harl (e.g. Mantles). NO living animal has two harle genes: the mutation that with one "dose" causes a merle coat to become the distinct Harlequin color is lethal when the dog inherits two copies of the harle mutation. All true genetic Harlequins & genetic Whites have one harle gene. All merles & merlikins do NOT carry the harle gene. Any other color of Dane CAN carry the harle gene, as the gene only expresses in the presence of the merle gene. Over 60% of Harlequin-bred blacks (includes Mantles) carry the harl gene from GDCA research. To test for Harl contact: DR. LEIGH ANNE CLARK: firstname.lastname@example.org
*Only genetic level testing can completely confirm the phenotype of a dog.*
FOR MORE INFORMATION ON TESTING & QUESTIONS ON COAT COLOR GENETICS IN THE GREAT DANE, CONTACT THE CHAIRMAN OF THE GDCA HEALTH & RESEARCH COMMITTEE: DANEHEALTH@GDCA.ORG
Return to Health and Welfare section