That post title is a book title, so of course I had to blog about it ;-)
The book is by David Edmonds and John Eidinow, it’s about Jean-Jacques Rousseau and David Hume, and it’s been reviewed by Darrin McMahon in the New York Times (registration required).
The “dog” refers to Rousseau’s delusional tendencies, but he also owned a dog named Sultan, who, McMahon writes, was “the only being with whom he could find the peace of true friendship in England.”