First, credit for a whole bunch of stuff here to Dr. Schmutz at the University of Saskatchewan; she has done more for our modern understanding of dog color genetics than anyone else I can think of. I am always fascinated by her writing and try to keep up with what’s being disovered. The below is VERY NEW STUFF; it was not what I “knew” even last year.
A little background:
When I was getting started in Danes, I was considering which color family to get involved in. While there is some overlap, and I rebelled eventually and did cross-color breedings, the color families in Danes are pretty rigid and you have to decide which color you want to pursue.
When I researched harlequins, and the mantle color that went on to be approved as a showable color, there was quite a lot of mention of how difficult it was to get a “show marked” harlequin or mantle. This means, with some leeway for more or less white, a white collar, white on the legs, and a white blaze. All-over harlequins are very definitely not preferred and you’d have a difficult time finishing one. If you look at this litter by a FABULOUS harlequin breeder that was a wonderful friend and help to me when I was getting started in Danes, you can see that she won “the harlequin lottery,” with an entire litter of show-marked or close to show marked puppies. Notice how the harlequin puppies also have a big fat white blaze and white necks and white legs; they’re mantle-marked as well as harlequin.
My fellow Cardigan lovers look at an evenly marked litter like that and think, “Well, sure, but all of my litters have looked pretty much that good.” A Dane person looks at that and the words “won the lottery” really are quite accurate.
In an average harlequin Dane litter, the number of show-marked dogs is very small. Often only one or two display the desired collar, blaze, and legs. Some puppies in the litter are usually merle (which is a disqualification in Danes, so most are sold as pets), but even the ones that are harlequin or mantle are often mismarked. They either have too much white (and here I mean the white markings, not the white areas between the harlequin patches) or too little.
A very similar thing happens in Boxers, another breed where the desired color is a collar, blaze, and white legs. These “flashy” Boxers, when bred to other Boxers with similar markings, don’t produce a whole litter of evenly marked puppies. You hope for a few, but you know you’re likely to get plain (solid-colored) dogs, which are considered less likely to show successfully, as well as mostly white puppies that are disqualified and either placed as pets or (if deaf) often euthanized.
Bull Terriers show the exact same spectrum of markings, only in that breed you can show the solid and minimally white dogs as well as the completely white ones (one more example of the “game” of dog showing that doesn’t make a lot of rational sense, but that’s the way it goes).
Little (in the 50s) defined white spotting in three divisions – irish, which meant white collar, blaze, and feet (though the collar could be minimal); piebald, which meant that the body color was broken up into spots and the white on the legs took up most or all of the leg; and extreme piebald, which is the white spotting like white Bull Terriers and white Boxers have – almost no color on the body at all.
The problem with Little’s definition was that it was so impossible to breed that elusive collar/blaze/feet pattern consistently, in so many breeds. If it was an established color, genetically, you should be able to breed two desirably marked dogs and get all desirably marked puppies, not have the pendulum swing wildly back and forth.
And the additional mystery was that in some breeds – Cardigans are one of them, as are Border Collies – the color DID work predictably. So what on earth was going on?
Some of the puzzle was unraveled when researchers determined that there are a couple of mutations in a gene called MITF that can cause white spotting in dogs. They also determined that white spotting in dogs is NOT the same as white spotting in, for example, cows, despite the resemblance visually.
MITF was identified as the gene that causes spotting in Boxers, Bull Terriers, Landseer Newfoundlands, etc. Hoorah! White spotting solved!
When a Shetland Sheepdog, with a full gorgeous white collar and white feet and a white blaze, is tested for MITF, the result is “solid.” The dog is “not spotted.” It’s a completely unmutated MITF gene.
So what on earth is going on?
Well, the answer is that the white blaze and collar and feet on Shelties (and Collies and Corgis of both types and Border Collies and so on) is a DIFFERENT mutation. The white color may look the same as the white on a Pointer, but what’s causing it is a different phenomenon. Just like the spotted cows are caused by a different mutation than spotted dogs, herding-breed markings are caused by a different mutation than many of the other breeds. That’s why herding-breed markings are so predictable; whatever mutation it is seems to be more “stable,” if you want to talk about it that way, than the wide variations conferred by the mutations on MITF.
Cool, huh? Very. But let’s throw a wrench into the works – because as it turns out, MITF is also in the herding breeds, in addition to our mystery mutation.
A single copy of the mutated MITF gene, when added to the “herding-spotted” mutation, pushes the white up higher on the hind legs, up to the flank, and often puts a small break in the solid blanket over the dog’s back.
Sound familiar? Yup, a single copy of MITF is responsible for “white factoring” (which is what Cardigan people call “looks like she’ll probably produce mismarks”). Interestingly, MITF does not seem to make blazes any wider or collars any bigger; you can have huge white collars and big fat blazes on a MITF “solid” dog, and only small blazes on white-factored dogs.
So mystery mutation = white blaze (thin or wide), collar (which may be thin or fat), front feet (or entirely white front legs), back feet, tail tip.
Mystery mutation + MITF = all of the above plus a high slice of white on the back legs, up into the flank area.
In Collies and Shelties, these “white factored” dogs are sometimes bred together, because some fanciers really like the piebald or color-headed-white dogs. In this case some puppies will get two copies of the MITF mutation and will be the same color as a Pointer or a Landseer: mostly white with some patches over the body and (typically) round patches around the eyes and ears.
In Cardigans, we label these piebald dogs as “mismarks” (again, see the game? Same genetics, totally different decision on the part of the breed club), so if we have a dog that has a bunch of white (and is probably white-factored, though most Cardigan breeders don’t look at the color and try to label it the way Collie or Sheltie breeders do) we Cardigan breeders tend to breed him or her to a dog with more minimal white. We do mystery + MITF x mystery, or mystery x mystery, as the vast majority of our breedings. As a result of these rather “instinctive” breeding choices, even though we haven’t understood the genetics behind it, we only very rarely end up with piebald dogs. Of course they do exist, and if you really wanted to make them you could easily do so by looking for Cardis with white going up on the flank.
OK, now, before I get mad or confused comments: In Cardigans we also have a mismark that is confined to the head; I’ve heard it called “white-ear” a couple of times and that’s as good a name as any. It’s when the blaze and the collar are so wide that they meet in the middle, removing the color on the ear and around the eye to a greater or lesser extent and causing breeders much angst as they try to figure out what “white should never surround the eyes” should mean to them. (Is “surround” the operative term? “Eyes,” so one eye is fine? If there’s a tiny brown spot over the eye, does that mean that white should not surround that? And so on.)
I strongly suspect that white-ear or head-only mismarking is related to the strength (for lack of a better term) of the “mystery” mutation, and not is the result of MITF. I think this for two reasons: a) because if it’s MITF then we should be seeing a lot more piebald Cardigans, because it’s not uncommon to breed dogs with big blazes and wide collars together, and b) because those dogs usually have normal white back feet and the white does not extend up into the flank.
So there you go! A small intro to Cardigan spotting, with a big caveat that while the information that’s out there is good, and WORLDS better than it was even five years ago, as genetic study of dogdom continues we will get more and more (and more precise) information on spotting as we will on so much else.
By the way, Clue (who has a lovely white collar but doesn’t have a ton of white on her head) has white going right up her back legs into her flank. I can see the same marking on her mom (but not her dad), and some other offspring of her mom’s sire also have it so it probably came from him. And on and on it goes, up the pedigree. So if Clue is bred to a boy with a lot of white, she’ll probably produce mismarks. That kind of thing has really never bothered me, but if I was super serious about it I’d be on the lookout for a boy with little white back feet. As it is, whatever we get from her will be nothing but wonderful and perfect. 😀
Note: if you came here from a search engine or only see this post, you should also read the continuation, here: https://rufflyspeaking.wordpress.com/2009/05/05/white-spotting-cont/