No, it means (if you had it in CanHaveMoreFollowers) that you could buy a third dog only if you had at least one brahmin, 4th dog if you had at least 2 brahmin and so on. It would disable party points system for dogs, at least within this function.
The easiest way to do what you want, is to make every dog "shepherd dog", then all you have to do is to change
return(Brahmin < 1 + (GetNumberOfType(player, FOLLOWER_TYPE_DOG) / 2));
to
return(Brahmin < 1 + (GetNumberOfType(player, FOLLOWER_TYPE_DOG) * 2));
And every dog will increase your max number of brahmin by 2.
Otherwise you would have to make a whole new type of follower (dog shepherd) and modify scripts in a few more places.