Or a kitten, bird, fish, hamster, gerbil, ferret, mouse, or pot bellied pig.
Even if there are pets in the house--they will want more pets. Especially the young version of any animal they may choose. It seems kids just know they are on the same level. (CLICK HERE to see a few pix that drive that point home just a bit ;) ).
They also like being around each other. They both have endless energy to play and can help with your already greatly diminished energy level.
I think this is also the reason kids love books with animals. They have a natural love for the outdoors and nature, and animals in books, whether anthropomorphic or real capture their attention. Even the Cat in the Hat, who bears only the most faint resemblance to a feline, (I think he kind of looks like Jack Benny), grabs their attention.
It's a mutual admiration society, kids love animals and animals love kids.
Even my favorite book as a child, Where the Wild Things Are, has animals in it--kind of...
Some scientists warn that kids could get confused if reading about animals that have human traits. I think
(I'm not a doctor) that we do not give kids enough credit. I do not think Winnie the Pooh, Dory the fish, or Snoopy did me or any other kid any harm.
Has it been done already? Yep. But kids love it, and it will be done again. I'll do it in my next book in fact. And I'm pretty certain all the kids will be fine even after they see the main character in the book is a mouse, and he wears a vest.
I think they will be just fine. :)