I actually did a bit of testing about this yesterday. It was for a mod I'm hoping to make:
http://www.bay12forums.com/smf/index.php?topic=101433.0I first tried transforming dogs into Dwarves. It was successful, but a bit strange. They could work real jobs (I tested masonry and animal training), but had no name, and could not gain skills. If they had been assigned to someone previously, they would default to following them when they had No Job. Could not assign them noble positions. Finally, if they were in a pasture when transformed, they would remain in the pasture and also show up in the animal screen and were butcherable.
Second, I tried transforming dogs who had the [INTELLIGENT] tag. They began the game with names, and gained social skills from standing around. Once transformed, they behaved as before, but with the ability to learn. When they changed, their names remained the same, and their descriptions were more coherent. Unfortunately, sometimes they would switch gender mid-description. Still wasn't possible to assign them positions of nobility. I believe the [PET] tag may be responsible for this.
Anyway, I'd love to know if anyone else is doing testing on this. If there's any way you can get rid of (tame), I bet nobility would work.
EDIT: Just did a little more testing with castes... It seems that even with the [PET] tag, a caste of dwarves can be put in a position of nobility. [PET] is definitely responsible for (tame) though.