So supposedly I have a dog following me so I can't have any trolls following me.
The only thing is I don't actually have a dog following me around, it's just me and Serena.

The first dog I met was Barbas, but he went to his masters shrine in the mountains.
The second I met was a stray dog north of Markarth around that area, along the dirt paths in the hills but not across the river that runs to Solitude.



Is Barbas considered a companion even though he went to his masters shrine by himself?

Or is the dog that followed me for a while and then wandered off still considered a companion?
I looked around but I can't find the stray dog's spawn point north of Markarth, could someone show me where it is?

Not sure, but it is possible that the game is treating Barbas as an active follower right now. You could try completing his quest, and then try recruiting a troll. Alternatively, you could try dismissing Serena and then recruiting a troll (because i'm not sure if you can actually have both at the same time).

I read his page, I'm not sure which dog I met first.
Perhaps I met the stray dog first and then it died or something, it's no longer in my party.

http://www.uesp.net/wiki/Skyrim:Barbas

I think you're right and he was perhaps the last dog I met and he is still being counted as a follower.



I think that means he is still being included as an animal follower until I complete the quest, hopefully if he is still being counted he won't stay there forever as this bug suggests.