I recently got my first male St. Bernard puppy from a breeder. Do you know if there is a genetic cause for the rare half mask? Also my puppy has fully formed rear dew claws but his front dew claws were removed shortly after birth. I have read that the rear dew claws are not uncommon in the breed. Is there a gene specifically for the rear dew claws?
Forums > Saint Bernard Genetics: Face markings(Mask) and Rear Dew Claws
The classic mask seen in St. Bernard dogs is a pattern called "piebald". Clarence Cook Little, a dog geneticist, discovered in the 1950s how this coat color pattern is inherited and described it as the "S" spotting locus. Later, three groups of scientists independently found the gene responsible for this pattern: MITF. Elinor Karlsson has found that differences in the DNA around this gene, MITF, seem to result in differences in the extent of the piebald pattern.
While I cannot say for certain what causes the half mask in St. Bernard's, I think the gene MITF may be a good candidate for its genetic basis!
The genetic cause for hind-leg dew claws has been attributed to a few different changes in the gene LMBR1. This gene controls hind-leg development. It has also been involved in human polydactyly -- that is, people having extra toes!
I hope this helps. Let me know if you have any more questions!
Great question Chere, and thank you Kathleen for your knowledgable reply!
Just so our participants are aware, Kathleen is a graduate student in the Karlsson lab researching canine genetics!