RE: Explaining to Children Why They Cannot Have a Dog
Unless the parents want to care for a dog, it is probably a better idea not to get one for that young of a child. If she is very young, she won't be able to do all the necessary cleaning and changing of pads, and feeding that will have to be done; and after a few weeks of having a dog, a child usually gets tired of taking care of them, anyway. And if she gets a puppy, then it needs to be house trained as well.
I would try getting her something like a hamster, and see how she does at taking care of that first. That way, she can learn responsibility for having a pet, and it would be something that CAN live in an apartment, and also one that a child can care for, and play with. Hamsters are intelligent little creatures, and make great pets, and maybe it would be all she needs to satisfy that longing for a pet of her very own.