This is the book the Movie of the same title is based on. This isn't the first time I have read it, nor even the third. If it has been a while since you have, or if you are planning to see the movie, read the book. If they keep close to the concept in the book reading it will help understand some of the things they don't tell you about. For whatever reason you read it, I suggest that you pay attention to the instructor in History and Moral Philosophy, Mr. Dubois. Not only does it explain Johnnie's society, in some instances it pretty well tells of ours, almost 40 years after the book was wrote.
Lummox has been the pet of John Thomas Stuart for all his life. He was also the pet of his father amd grandfather, and great great grandfather who found him on one of the earliest explatory missions by a space ship from Earth. Looking something like a cross between a hippo and a dinosaur with eight legs Lummox is considered a large pet, There has been no official classification as Lummox had been sneaked in although the locals knew about him. Then Lummox decides to go for a walk and the trouble starts. It ends with Earth almost involved in an interplanetary war.
I recommend you read this book if you haven't. If you have and it has been a while read it again..