I made the choice to be vegan because I will not eat (or wear, or use) anything that could have an emotional response to its death or captivity. I can well imagine what that must feel like for our non-human friends - the fear, the terror, the pain - and I will not cause such suffering to a fellow living being.
The more we learn of the true nature of non-human animals, especially those with complex brains and corresponding complex social behavior, the more ethical concerns are raised regarding their use in the service of man -- whether this be in entertainment, as "pets," for food, in research laboratories, or any of the other uses to which we subject them.