Here are some more of my faves:

"There is no psychiatrist in the world like a puppy licking your face".
-Bern Williams

"No matter how little money and how few possessions you own, having a dog makes you rich".
-Louis Sabin

"Dogs love their friends and bite their enemies, quite unlike people, who are incapable of pure love and always have to mix love and hate".
-Sigmund Freud