William Youatt

“The ox and the sheep submit to our control, but their affections are principally, if not solely, confined to themselves. They submit to us, but they can rarely be said to love, or even to recognise us, except as connected with the supply of their wants. The horse will share some of our pleasures. He enjoys the chase as much as does his rider; and, when contending for victory on the course, he feels the full influence of emulation. Remembering the pleasure he has experienced with his master, or the daily supply of food from the hand of the groom, he often exhibits evident tokens of recognition; but that is founded on a selfish principle—he neighs that he may be fed, and his affections are easily transferred. The dog is the only animal that is capable of disinterested affection. He is the only one that regards the human being as his companion, and follows him as his friend; the only one that seems to possess a natural desire to be useful to him, or from a spontaneous impulse attaches himself to man.”
― William Youatt, The Dog