I'm not a fan of Jeremy Bentham's overall philosophy but on some things he was totally on the nose, and I just love this quote of his (the bolded part is the Cliff's Notes for anyone who doesn't want to read the whole thing):

"Other animals, which, on account of their interests having been neglected by the insensibility of the ancient jurists, stand degraded into the class of things. ... The day has been, I grieve it to say in many places it is not yet past, in which the greater part of the species, under the denomination of slaves, have been treated ... upon the same footing as ... animals are still. The day may come, when the rest of the animal creation may acquire those rights which never could have been withholden from them but by the hand of tyranny. The French have already discovered that the blackness of skin is no reason why a human being should be abandoned without redress to the caprice of a tormentor. It may come one day to be recognized, that the number of legs, the villosity of the skin, or the termination of the os sacrum, are reasons equally insufficient for abandoning a sensitive being to the same fate. What else is it that should trace the insuperable line? Is it the faculty of reason, or perhaps, the faculty for discourse?...the question is not, Can they reason? nor, Can they talk? but, Can they suffer? Why should the law refuse its protection to any sensitive being?... The time will come when humanity will extend its mantle over everything which breathes... "
Jeremy Bentham (1748 - 1832)
Introduction to the Principles of Morals and Legislation

I very much believe that animals are emotional and empathetic. And I feel like anyone who has had a pet would agree, especially if that pet is a dog, who show so much character, personality, emotion, all of it. To me though, at the end of the day, what matters is that it's unquestionable that they can feel pain. Even if they were not able to emote, we should be kind to them for that reason alone.