- O Despertar Da Força
- O Dragão De Eletricidade E O Pássaro De Água
- O encantador de gatos
- O Gato Curioso
- O gato do rabo comprido
- O Jacaré E A Lagartixa
- O Jumentinho E O Rei
- O manifesto das espécies companheiras
- O Menino Do Olho D'água
- O Mundo Secreto
- O Olhar de Capitu
- O Pinheiro E A Fonte Dos Iluminados
- O Sangue De Bibi
- O Segundo Jardim
- O Tarot Do Jogo Do Bicho
- O životinjama i njihovim ljudima
- Oak Tree Farm
- Oboe's Story:When Our Dog Needed a Hero
- Observations On Modern Falconry
- Observations on Modern Falconry
- Ocean of Life
- Octopus, Squid & Cuttlefish
- Odd Bird
- Of Cats and Kings
- Of Cats and Men
- OF ENGLISH DOGS (VINTAGE DOG BOOKS BREED HISTORY SERIES)
- Off Leash Dog Play
- Office dogs: The Manual
- Oh Look, You've Bought A Puppy!
- Oh No! Look What the Cat Dragged In
- Ohh Scruff!
- OHNE SCHULD - DIE GANZE GESCHICHTE [von der SPIEGEL-Bestseller-Autorin]
- OHNE SCHULD - DIE GANZE GESCHICHTE [von der SPIEGEL-Bestseller-Autorin]
- Old Cat, Fat Rat, And Boo
- Old Dog 101 - Tips & Tricks for Senior Dog Care
- Old Dog Love: A Common-Sense Guide to Caring for Your Senior Dog
- Old Faithful
- Old Mother Hubbard and Her Wonderful Dog
- Old Spouse's Tales about Animals
- Older and Wider
- Older dog? No worries!
- Oliver – A Story of Love
- Ollie and Nina and ...
- Ollie's Lost Kitten
- Omphalos
- On a Starry Night
- On Cats
- On Horsemanship
- On Nature
- On Talking Terms With Dogs
- On the Edge of Infinity
- Once Upon a Flock
- Once Upon A Pony
- Once Upon a Puppy
- One Big Happy Family
- One Hundred Dogs and Counting
- One Hundred Muddy Paws For Thought
- One Hundred Secret Thoughts Cats have about Humans
- One Lucky Pom
- One Man and a Mule
- One More...Cat Diary 4
- One Perfect Kiss: Hope Book 8
- One Unforgettable Journey
- One Way Soldiers Die
- Only a Dog
- Onomatopeia - Sons De Pessoas,objetos,animais E Coletivos
- Oodles of Doodles
- Oogy
- Operations Manual for the Chinese Crested (2nd Edition)
- Operations Manual for the Xoloitzcuintli (2012 Edition)
- Orca Orcinus
- Oreo's Story
- Origin Story
- Origins of the Modern Bulldog (British Bulldog)
- Orion's Bunny Care Guide
- Ornamental Gardening In Acadiana & the Gulf States
- Os cães nunca deixam de amar
- Os donos do pedaço
- Os Gatos
- Oscar by My Side
- Oscar e me
- Oscar J: Skipper Can No Longer Play... and Daddy Can No Longer Stay...
- Oscar's Diaries, Life as a Retired Greyhound (Vol. 1)
- Oscar: The Bionic Cat
- Oscar’S Snippets
- Oskar - ein Leben in der Stille und trotzdem mittendrin!
- Oskar der Hund
- Other People's Horses
- Otherlands
- Our Best Friends
- Our Best Pal: Gander
- Our Black and White Babies
- Our Canine Companions
- Our Cats and All about Them - Their Varieties, Habits, and Management