I've read many books on dogs, specifically Chihuahuas since I have two of them. What I have noticed in all the books I've read is although they give good instructions on how to house train, groom, feed, and avoid illnesses regarding your companion animal, not one mentions in depth on the many personality, less noticeable physical, and emotional differences of a male and female dog; I wonder why there is not much information on this in a book?
This is about as much information I could find anywhere:
It's difficult finding information about male and female differences in general, and much less on male and female difference according to specific breeds. Surely there are many differences.
Places where I do find information about the differences between genders, they are in regards to when choosing a companion animal and not pertaining to just scientific research.
Maybe authors feel there isn't much to say about gender differences, but I feel that those who write a half-way informative amount in an article could flesh it out into a book, or even a decent size booklet.
I think possibly the best thing for me to do is not to look for companion animal books for the average person interested in getting a companion animal, but to look for some sort of historical, zoological dog book to find the full truth about male and female dogs, or any kind of companion animal.