This post first appeared on August 18, 2011
I am back from my recent trip to Germany, and have some quick posts from there before I pick back up on the topics from the previous week.

We were visiting family friends in Landstul, so it was not a work-related trip. That meant my chances to see horses were limited to what we passed along the roadside. My husband is rather accustomed to my requests that we pull over the car to get pictures of unusual horses; European train conductors are not quite so flexible. I did come across a lot of dogs, though, including this blue-eyed Greater Swiss Mountain Dog.

I only got this one, poorly focused front shot to show that he had one dark and one blue. From what I understand, blue eyes like this occur upon occasion within the Greater Swiss Mountain Dog population. They are a disqualification in the show ring, so dogs like this one are usually sold as pets. The trait is mentioned pretty frequently on sites dealing with Swissies, which makes me suspect that it is not that terribly rare.

I also suspect that this is the same separate (ie, unrelated to merle or piebald) blue-eyed gene that occurs in Siberian Huskies. From what little research I have done looking at litter records, blue eyes like these are recessive. What makes it hard to be sure is that the gene appears to have variable expression, with some dogs – like this Swissy – having bi-eyed or partial blue eyes. What is interesting about its presence in the Swiss Mountain Dog is that it is also known to happen in Rottweilers, which is thought by some to be related to the Sennenhund breeds, of which the Greater Swiss is one. It may be that the Sennenhunds, which are a relatively old breed group, are one of the sources for the gene. The fact that it is also found in something as distant to the Swiss cattle dog breeds as a Siberian Husky suggests that it is quite an old mutation.

That is an idea that I hope to touch upon in a later post dealing with (horse) breed relationships. I brought breed dendrograms like this one with me when I did the presentation on breed colors in San Diego earlier this year, and they were the subject of a lot of interest.