Pets. Cats and dogs. Usually not ants and frogs.
I don't wish to talk about the joys of pets, but of the ethics of pets. And ethics, maybe not as absolute as I'm not sure if you could establish absolute ethics for animals, but as how I see them.
Animals come and go in the wild. They eat eachother. They coexist. They ignore eachother. They do many things, and I'd generally label it "nature" and not something to intervene with a whole lot. Taking an animal outside of that seems to have the effect of changing its behavior, physique, and abilities, that it's not nearly so able to handle natural life. Add in selective breeding, and these animals are doubly unsuited for the wild in any sort of balanced way.
The problem I see is that pets are often the whim of a child, who gives up on them after a few weeks. Sometimes the animal is just kicked out of the house. Or sent to a shelter, where it's possibly put down. I don't think these animals are quite like material objects. It's a shame to waste a material thing (though completely up to you if you do so), but I think far worse to waste a life.
To this end, I think if you are looking for a pet, you should understand the responsibility it is to take care of it. For instance, boarding a cat for life seems to cost about $5,000. Probably a little more if you do it yourself. If you're to do it right, you should set aside that money if you can't take care of the pet. Or worst case, if it only has miserable options, reasonably put it down before it's out in the "wild" where it has no chance.
I can understand the breeding of very specific animals, like sniffing dogs, race horses, and maybe even less allergenic animals. But even so, it's sad to see so many animals inbred until they have problems and sold, where they are farmed out. It's not like it's hard to find a pet; there are far more pets than looking owners. Why get one new when there are so many you could take from the shelter?
And this is obvious, but we have an animal problem and just about every dog and cat probably should be spayed/neutered, with few exceptions.
I write this because I'm taking in a cat who has basically no other home possibilities (after a month of searching) and would have to be put down otherwise. A couple of years ago, my friend and I found her around her apartment and she took her in from there. Maybe she was a stray or an abandoned cat, I don't know. But it's needless to put these animals through this.
To be clear, I'm not calling for legislation or anything of the sort. Just personal responsibility and thought.