Well sometimes it is hard. Sables can carry only one black gene either tri or bi. If you have a sable with a black parent and a sable parent. The sable gene came from the sable parent and the black gene came from the black.
If the black dog is a bi you know that your sable is bi factored as there is no other option. However, if the black parent is a tri then is depends on what black genes they are carrying. You know there is a tri gene as they are tri but the other gene(the hidden gene) could be a tri or a bi depending on what their parents were. So which one did your dog get? Sometimes you don't know unless they are bred and produce a bi pup. It can be just as unclear if the parents are sables as the black gene is hidden. You really need to look at the pedigree and then still might not know. Confusing.
Here is my example:
Diva is a tri(Tri/?). Her mom is a mahogany Sable(S/?) same color we are talking about. Mom's parents were a pure for sable and a Bi factored Tri(Tri/Bi). So mom could be a Bi factored or Tri factored Sable we don't know. She has only been bred to a black dog(bi factored Tri) once and 2 Tri produced so we still don't know as the tri gene could have come from the dad. If Diva produces a bi we still don't know as again she could have gotten the bi gene from dad but if she never produces a bi pup when bred to a bi factored dog there is a good chance that she is Tri/Tri and mom is tri factored. The way to straighten it out for sure would be to bred mom to a Bi black if a Tri is produced , you know Mom is a Tri factored Sable. Make sense?
To give you idea how hard it is to determine if a dog is bi factored. Ember's(Bi/Bi M/m) mom is a bi factored Sable(S/Bi). Her dad a blue merle(Tri/Bi M/m). None of his parents were Bis and none of his 4 Grandparents were Bis. The bi gene come from his great grandsire, Ember's great great Grandsire. It skipped down that many generations unknown before it showed up again.
Wow, I had no idea it was this complicated. I knew there were tri-factored and bi-factored, but I though it just depended on their parent. Like I mentioned earlier with Meggie. I'm not sure I understand all of it, but it is very interesting!
