It isn't easy to dispose of an animal in a decent way. Pet shops are often reluctant to take pets back when they are too old and animal shelters are crowded. Usually one has to give the animal and its belongings away for free, or have it put to sleep. It seems like there's something wrong with the animal that is unwanted. The short period of time that the child is involved with the pet, the child should learn some responsibility, but instead it learns that one is allowed to lock animals up whenever he wants, that the animal can be abandoned and that the pet only needs attention when it's fed.
Few people wonder if locking an animal up is really for the welfare of the animal.
To be really sure of this, one should think about the life and living space of the animal. The animals that stay voluntarily or drop in on someone should be the animals kept as a pet, and all other animals, that choose freedom, shouldn't. Children will get attached to an animal or they won't. It wouldn't be strange for someone who loves animals to make the choice not to have any. It usually seems that animals want to be independent and left alone.