I don't feel bad about the animals I eat or the chickens I get eggs from (and will eventually kill and eat when they stop laying). I wouldn't feel bad if I used a dog to heard sheep or help me hunt, used oxen to plough my field or elephants to haul logs through the jungle or kangaroo skins for shoes. Why would I feel bad about any of it?

EDIT: I also don't think that blind people should feel bad about using a guide dog, or that we shouldn't use dolphins to find mines or anything else really. If you can use it, use it! I only object to senseless torture and torment.