No, no real dominant. Some colours are simple Dominants, in that they need to be there in a parent in order to express, and some colours and patterns can be Homozygous, in that the pattern will always express. ie H/Z Tobiano will always produce a Tobiano, but the pattern may be so minimal it would take a magnifying glass to find it!!!
Also a H/Z Black will always throw a Black
based horse BUT if there is Agouti hiding in the sorrel mare- you can get a Bay, if the mare is Palomino, again hiding Agouti, you can get a Buckskin (Cream + Agouti+ Black) All the Homozygosity guarantees is a black
based horse which is why it is important to know the
real colours of the ancestors, not just the ones shoved down on the papers. The only real, hard and fast rule is Sorrel X Sorrel
always= Sorrel, after that I'm afraid the only set in stone rule is that there are NO set in stone rules!!!! You can guess more accurately if you
know the colours that you are dealing with are 100% accurate- I have bred my own horses for five generations so I
know the colours are accurate??? WRONG I mis- identified a mare as Palomino for EIGHT years of her life!!! I
bred her, I was there when she was born!!! She is a Dunalino, genetically. She
looks like a Palomino, you need a good day, a clean horse and a magnifying glass to find the dorsal stripe- BUT she threw a Red Dun to a non- Dun factor Stallion- so, she
has to be a Dunalino!! Colour is SUCH good fun