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Joker is a lurcher (sighthound mix) who lives in Europe, and to me his breed is more of a mystery than his genotype. His coloring most likely came from a collie of some sort. Collies and terriers are the most common breeds used in creating lurchers. The wire coat could have come from two sources: a wire-haired sighthound, of which there are several, or some sort of terrier. It is possible that he is a multi-generational cross, as it isn't unusual for several different sort of crosses to be done in an attempt to create the ideal dog. For those that don't know, lurchers are purpose-bred mixes used for hunting, combining the speed and instincts of a sighthound with whatever other desired trait the breeder wants (which is usually the basis for whatever pairing is chosen). Now, Joker is a rather large dog. There are a wide variety of breeds that could have gone into making him. I don't have one best guess for his breeding, but I think he is most likely a cross of collie (possibly a merle border collie) and some sort of wire-coated hound such as a deerhound or galgo (Spanish greyhound).
Anyway, so what's his genotype?
The first gene that must be expressed on Joker is what makes him black. There is no hint of tan or red on his body, and as such he must be black. Though there is recessive black, it is highly unlikely that is what he is since it is an unusual gene in dogs, and appears to be absent in sighthounds. However, I honestly doubt that Joker is homozygous for the black gene. Brindle is quite common in sighthounds, including the two breeds I mentioned. As such, I suspect that Joker is Kkbr black carrying brindle.
Clearly, Joker is also merle. Since he is a mix, I highly doubt that he would be homozygous for the gene. In addition, the white seen on him does not fit what usually is seen in double merles. As such, he must be Mm merle.
Last, but not least, the only other gene that can be guaranteed to be affecting Joker's coloring is the Spotting gene. He shows classic Irish white markings: white on all four legs, tail, face, and a white collar. Though it is possible that he is solid carrying extreme white piebald (as this is known to produce Irish white markings), it his highly doubtful. I suspect that he is what would be the simpler explanation: sisi Irish white.
So, that would be Kkbr Mm sisi or merle and white.