Hi Jamestrd,

 

I understand what you mean to say by all dogs are either black or "liver", but here we have another common name (liver) being used in the wrong context.  what you are saying by "genetically all dogs are either black or liver" would most often be referred to in genetic terms as black/eumelanin or red-yellow-fawn/phaeomelanin. red/phaeomelanin being what you are calling liver? so you are correct... but liver is not the correct term. 
in the link submitted by Basenji Zeke and most other canine coat color genetics articles "liver" is described as being bb genotype which changes all the BLACK/eumelanin pigment to brown (aka LIVER!). thus we always have the brown noses on all "liver" colored dogs but not on red or black dogs with BB (or Bb as you mentioned) genotype who always have a black nose(unless they are blue fawns[BBdd, Bbdd genotype] then they have blue noses).

you are also correct that a standard colored Thai Ridgeback COULD be carrying the b gene(Bb), but we would then expect to see them regularly with b being a simple recessive just the same as d(blue). we see lots of blue and blue fawn Thai Ridgebacks but never any liver colored(brown nosed) Thai Ridgebacks. if the Bb genotype was at all common in the breed we would surely see just as many liver/brown nosed dogs as we do blue/blue fawn colored dogs. so i think its safe to say the vast majority of standard color Thai Ridgebacks dont carry the b(they are not Bb genotype), and are always BB/with black or blue noses.  Rhodesian Ridgebacks on the other hand very often come in liver/with brown noses and it is an accepted color in that breed. 
Anybody have or ever seen a Thai Ridgeback with a liver/brown colored nose? I have seen some Thai dogs with brown noses and some of them with ridges! but then i dont consider them to be Thai Ridgebacks or standard colored.

 

so if anyone is confused do your research. start with that link/article from Basenji Zeke and compare it to at least 10 others.

James ... www.ManapeThaiRidgeback.com