Who is Sparky from Welcome to the Monkey House and what is their importance?

Sparky is Edison's dog. The intelligence analyzer almost breaks when it is tested on him, revealing his extreme intelligence. According to the stranger's story, Sparky speaks English and sets both Edison and the stranger for life in exchange for their promise not to betray his secret. Even so, the other dogs are already on to him, and Sparky is killed as soon as he leaves the laboratory.