Is it fair to do this?

I agree with leehack. I would give to the cats, or dogs, or donkey sanctuaries, or a numerous amount of other animal charities. I am not against charity for people, I have given to this in the past. But if I have a box of books, etc and want to donate them to charity, I always hand them into the PDSA.

Charity isn't a competition. Just because I, as well as many others decide to support animal charities, this doesn't make me a bad person. It also doesn't make people who decide animal charities are their preferred place for charitable donation wrong either. Some people give to sick and starving Developing Nations. Some people give to sick and starving animals. Both individuals are correct, but in their own ways.