This is a question about a missing detail in PF rules.
According to the Dog Breeds rules, Riding Dogs have a special quality called "Loyal" as Animal Companions at 4th level advancement. The problem is, I searched in every site I could find and I never found a description of it anywhere.
Then I really want to know what it is about exactly. Every other Medium dog breed seems to have a kind of special quality by default (mentioned and described in their bestiary entries) that they only have at 4th level advancement as Animal Companions.
By the way, a lot of special qualities of other dog breeds are left unexplained as well. I will take any explanation for them as well.