X/Y/Z

Yarbo, Chelsea Quinn
Dark Light [#2 in Shattered Light Series] (catmorphs) {A}

Yates, Elizabeth
Under the Little Fir, and Other Stories [I'm positive the title story at least is furry] (various woodland creatures) {IR}

Yates, Janet Lee
Skeeter Bug Loves Sarah (cat) {IR}

Yates, L. B.
The Autobiography of a Race Horse (horse) {A}

Yep, Laurence
The Tiger's Apprentice Series (shapechanging tiger, dragon, monkey) {IR}
1. The Tiger's Apprentice
2. Tiger's Blood
The Dragon Series (dragons, monkey) {YA}
1. Dragon of the Lost Sea
2. Dragon Steel
3. Dragon Cauldron
4. Dragon War

Yolen, Jane
The Acorn Quest (squirrel, groundhog, turtle, rabbit, mouse) {IR}
The Boy Who Spoke Chimp (chimpanzee) {IR}
The Dragon's Boy: A Tale of Young King Arthur (dragon) {IR}
Hobo Toad and the Motorcycle Gang (toadmorph, others) {IR}
The Mermaid's Three Wisdoms (mermaid) {YA}
The Wild Hunt (cat) {YA}
The Here There Be Series [not all stories furry] {YA}
1. Here There Be Dragons (dragons)
2. Here There Be Unicorns (unicorns)

York, Carol Beach
The Good Day Mice (mice) {IR}
The Christmas Dolls: A Butterfield Square Story (dolls) {IR}

Yoshizaki, Mine
Sgt. Frog Series (frog) {YA/A}
1. Sgt. Frog 1
2. Sgt. Frog 2
3. Sgt. Frog 3
4. Sgt. Frog 4
5. Sgt. Frog 5
6. Sgt. Frog 6
7. Sgt. Frog 7

Youmans, Eleanor
The Skitter Cat Series (cat, dog) {IR}
1. Skitter Cat
2. Skitter Cat and Major
3. Skitter Cat and Little Boy

Young, Egerton Ryerson
Hector, My Dog: His Autobiography (dog) {A}

Young, Gerald
Chunk, Fusky and Snout: A Story of Wild Pigs for Little People [AKA The Wild Pigs: A Story for Little People] (pigs) {IR}

Young, Lillian E.
Pussy-Willow's Naughty Kittens (cats) {IR}

Young, Steve
The Winchell Mink Series (turtle, dinosaurs) {IR}
1. The Misadventure Begins
2. (not yet published)

Yu, Yuen Wong
The Digimon Series [The Daniel Horn book does not appear to be connected with this series] (various animals) {IR/A}
1. Digimon 1
2. Digimon 2
3. Digimon 3
4. Digimon 4
5. Digimon 5

Zabor, Rafi
The Bear Comes Home [Contains fifteen pages of graphic oral sex between a woman and a bear...you've been warned!] (bear) {A}

Zahn, Timothy
Manta’s Gift (mantarays) {A}
The Dragonback Series (dragonmorph) {YA}
1. Dragon and Thief
2. Dragon and Soldier
3. Dragon and Slave

Zalben, Jane Breskin
Beni's Family Treasury: Stories for the Jewish Holidays (bearmorphs) {IR}

Zambreno, Mary Frances
Fire Bird [#5 in Voyage of the Basset Series] (various animals) {IR}
The Jermyn Series (skunk) {IR/YA}
1. A Plague of Sorcerers
2. Journeyman Wizard

Zaniewski, Andrzej
Rat: A Novel (rats) {A}

Zelazny, Roger
A Night in the Lonesome October (dog, others) {A}
Eye of Cat (shapeshifting feline) {A}
Psycho Shop [with Alfred Bester] (catmorph, snakemorph] {A}

Zaring, Jane T.
The Return of the Dragon (dragon) {IR}

Zimnik, Reiner
The Bear and the People (bear) {IR}

Zindel, Paul
Let Me Hear You Whisper: A Play (dolphin) {A}

Zuhdi, Darla
The Cat Detectives Series (cats) {IR}
1. Tale of a Christmas Angel
2. Finding Your Dream
3. A Tale of Three Amigos