What possible practical reason could there be for mutilating a pet? The question does not make sense. If we are talking about health reasons, that is one thing. But if we are talking about aesthetics or other superficial reasons, then there is no reason to let this kind of thing happen.
I definitely think that it is unethical to mutilate pets just for the sake of style and aesthetics. I do not think that people should be able to do such things like crop a dog's ears, etc. I think that such practices should be banned and regulated. I think that it is a form of animal cruelty.
Yes, it is unethical to mutilate pets for aesthetic or practical reasons, because pets hurt and have feelings. That is inhumane, and it is the mistreatment of animals, because animals suffer pain and even can have emotional pain, just like humans. There are other ways to entertain yourself than hurting someone or something weaker than yourself.
I do not believe it is completely ethical to mutilate pets for aesthetic or practical reasons, but at the same time I wouldn't classify most of these changes as mutilation. Tail docking has been very common in some breeds and I don't consider this mutilation and I don't directly equate it to a moral problem. In searching for information about ear docking, I was quite shocked to find the process involved. I think those cases are mutilation and they are unethical. The sheer amount of money that is wasted doing this isn't socially responsible.