The two coat patterns are merle and solid (remember, SELF is the dog without any copper or white, SOLID is the basic body color, a blue merle can be a self, but it can never be a solid). Obviously, the merles are the red and blue merles, and the solids are the blacks and reds. Here's a column for simplification.

Merles vs Solids

Merles	Solids
Red merle, blue merle	Black, red

Merle is an incomplete dominant over solid. Say what?? Total dominance means that you see one thing, even if the allele is not homozygous. (Like a red factored black), merle acts differently when it is heterozygous versus when it is homozygous. (Thanks Randy) Therefore, we assign merle, M, and solid, m. Easy enough, right? The solids are mm, and the merles are MM? Nope. What happened to the Mm's that you know there must be? Those lovely blue merles and red merles you see are not really merles! They are solid-factored merles. That's right, Mm. They are, essentially, half-merles. We refer to blue and red merles as heterozygous merles (meaning, two different alleles, which I have been calling traits in this essay). Homozygous merles (MM) are those famous lethal whites you've heard all about.

Now that you know the problems with homozygous merles, its up to you whether or not you want to breed them. You can easily avoid the problem of culling by only breeding heterozygous merles to solids. Likewise, you can also breed a homozygous merle to solids to get all merles. But, remember all the problems with them. If you want to try keeping a homozygous, you'd best be very experienced in the ways of breeding (ie, you already know this stuff I'm telling you about).

You want tables? I'll give ya tables!

Merles vs Solids

	Solid sire	Heterozygous merle sire	Homozygous merle sire
Solid dam	Genotype; 100% solid Phenotype: 100% solid m m m mm mm m mm mm	Genotype: 50% solid, 50% heterozygous merle Phenotype: 50% solid, 50% merle M m m Mm mm m Mm mm	Genotype: 100% heterozygous merle Phenotype: 100% merle M M m Mm Mm m Mm Mm
Heterozygous merle dam	G: 50% solid, 50% heterozygous merle P: 50% solid, 50% merle m m M Mm Mm m mm mm	G:50% heterozygous merle, 25% solid, 25% homozygous merle P: 75% merle, 25% solid M m M MM Mm m Mm mm	G: 50% homozygous merle, 50% heterozygous merle   P: 100% merle M M M MM MM m Mm Mm
Homozygous merle dam	G: 100% heterozygous merle    P: 100% merle m m M Mm Mm M Mm Mm	G: 50% homozygous merle, 50% heterozygous merle      P: 100% merle M m M MM Mm M MM Mm	G: 100% homozygous merle   P: 100% merle M M M MM MM M MM MM

Ahhh. . . now we tie in the color AND the merle. Its late, in fact, its 2:48 am as I write this, and as MUCH as I'd love to make you a HUGE table with all combinations, you aren't going to get it. Okay? So, how do you figure you color AND merle? Take the two separately. Are you breeding a red solid to a blue merle? You will get 100% red factored blacks, and you will get 50% merles. . . so. . . you will have 50% blacks and 50% blue merles, all red factored. Easy, isn't it?

Now remember, life doesn't always go by the numbers. A merle to solid breeding could produce all solids or all merles. That's the fun of it!!