This book is fiction, and could be a novel, short story, or novella, but set in the current time and real world when the book was published (sometime between 1960-1985). A famous night-time talk show (along the lines of The Tonight Show during the Carson age) hosts a segment featuring a guest who is a man with a very smart dog; the guest claims the dog can understand spoken conversation, beyond just verbal commands. There are a number of conflicts that arise; the main conflict is the sponsor of the show (a dog food company, I think) wanting to use the dog in advertising, but the dog’s owner refusing. I think it is set in Manhattan, and the book culminates in a dog fight on the ice of a pond in Central Park (between the smart dog, I think a golden retriever, and a doberman pinscher).