|Images provided to me by Susan Vaitekunas|
Izzy is a thirty pound female mix who was up for adoption when I received these images. I do hope she's found a good home. What's her mix? I was given two possibilities. On Petfinder, her listing was as a Jack Russell/Australian shepherd mix. However, it's believed that she may also have some miniature schnauzer, Australian cattle dog, and Irish red and white setter. I'll get back to her possible mix after I look at her genotype.
Since Izzy is expressing both black and red pigment, she is expressing one of the genes on the Agouti locus. Though it's possible she could be sable, I think she's actually agouti. Part of my reasoning behind this is the peppery appearance of the dark patches you do see, independent of what appears to be the effects of a merle gene. This looks to me like what is often seen in dogs known to be agouti, since the gene causes hairs in the coat to be banded. Due to reasons I will touch on later, I suspect that she is awat agouti carrying tan point.
The red in this dog's coat is moderate. Going with the idea that the Chincilla locus controls the intensity of red pigment, with would likely make this dog cchcch moderate red.
Next, Izzy is definitely merle. Though the effect is more subtle than what you would see on a dog with more black, you can still see patchiness of pigment int he black hairs that she does have on her head and hip. She also has blue in her eyes, including one eye that has splotches of both blue and brown. Though she has a lot of white, I think she only had one copy of the merle gene, making her Mm merle. Dogs with two copies of the gene usually have far less color on their heads.
The white seen on this dog, instead of being attributed to two copies of the merle gene, instead appears to be due to alleles found on the Spotting locus. The amount of color and placement of color patches are typical for what you can expect from a dog who is genetically extreme white, making Izzy swsw extreme white.
So, that's awat cchcch Mm swsw or white with agouti-merle patches.
Now, back to Izzy's ancestry. Though there is suspicion that she is part mini schnauzer and Irish red and white, I don't really see either of these. Though the schnauzer could potentially be a source of her agouti gene, it could have also come from another source. As for the setter, I find this doubtful due to how uncommon the Irish red and white setter is in the United States. I don't know if Izzy is actually from the US, but unless otherwise told I will assume that images submitted to me were taken in this country since this is where the vast majority of my views come from. As for the two main proposed breeds, I question whether a first-generation mix would produce a dog of this size, let alone one of this color. If she were a straight terrier/shepherd mix, I would lean toward her being part rat terrier.
My guess to Izzy's breed history? To me, she looks an awful lot like a feist or cur-type. Feists and curs are both purpose-bred mixes that are used for hunting. Though relatively consistent in type, they still can very a good deal and will come in just about any color. She leans heavily toward the feist more-so than the cur since she is fairly small in size, though on the big size for feists. I could be wrong, but this is what I see.