I'm going to call the animal shelter because I want to get a new dog.
Did something happen to the dog that you already have?
No, I'm just bored of that dog and I'd rather get a different one.
You made a commitment to your pet and you can't just get rid of it because you are bored with it. In fact, I doubt the shelter will even give you a new dog if you tell them that you are planning on getting rid of your old dog. Perhaps you are not a very good pet owner and you shouldn't have any pets at all.
It's my life and I can do whatever the hell I want. I don't need to justify getting a new dog.
It is your life but abandoning your old pet for a new one is not good. You could get banned from adopting a new pet if they find out you are not taking care of your old one.