I remember a book I read as a youngster and would like to identify it.
The premise is that a family somehow finds a pet (that was named ham ham or similar) that is sized like a football and is hairy and is able to fly or levitate. It has above-average intelligence - certainly higher that a dog.
One day they visit the park and some scientists abduct it and the family is devastated.
The book was first published at least 25 years ago.