His Dog Dick

https://www.smashwords.com/books/view/417258

A woman, Willi, meets a man, Peter, and is strongly attracted to him. He tells her he is a transman, and although she's never been with a transgendered person, she is undaunted. She is, though, taken aback when he tells her that rather than use a strap-on as a substitute penis, he has a dog trained for that purpose. She reluctantly agrees to try it, and finds that she does like it, and really does feel that his dog Dick is Peter's penis.
They settle into a happy relationship, until Peg, Peter's deranged ex-girlfriend, comes back to town. Peg rapes Peter in an especially horrid way, and Willie later takes a terrible revenge.

[Note: This story does feature transgendered persons, bestiality and nonconsensual sex. It is not recommended for persons who have difficulty with any of these subjects.]

http://www.barnesandnoble.com/w/his-dog-dick-arcadia-berger/1118887889?ean=2940149305520

Arcadia Berger has been writing erotica even longer than she has been masturbating, but the decrepit condition of her hands is not the result of either activity, but another form of self-abuse: manual labor at a job which is performed mainly by illegal immigrants. She found the immigrants to be intelligent and polite, and not at all snobbish about her lack of Spanish. The work was messy but not too unpleasant, but it really did a number on her hands, so she's hoping people will buy her stories.

"His Dog Dick" is Arcadia Berger's first, um, dog story, and she hopes it finds an interested audience. She has also written about other subjects, including age regression ("The Academy for Difficult Girls"), feminization of the female ("Taming a Tomboy") and Victorian/Steampunk erotica ("The Untold Story of From the Earth to the Moon"), and intends to move further afield.