The Heart of a Dog is a novella that blends science fiction with sharp social commentary. The story centers on a stray dog named Sharik, who is taken in by a scientist, Professor Preobrazhensky. The professor performs an experimental surgery on Sharik, transplanting human organs into the dog, which causes Sharik to transform into a human-like creature named Poligraf Poligrafovich Sharikov. Sharikov's transformation and subsequent behavior serve as a biting satire of the Soviet attempt to create a new socialist citizen. Sharikov becomes a crude, vulgar, and opportunistic character, embodying the worst traits of humanity. The novella explores themes of identity, the ethics of scientific experimentation, and the clash between nature and nurture.