Heart of a Dog

Heart of a Dog is a novel by Mikhail Bulgakov. It is a biting satire of the "New Soviet man". It was written in 1925 at the height of the NEP period, when Communism seemed to be weakening in the Soviet Union. 
Its theme is "the [Communist] revolution's misguided attempt to radically transform mankind". It has elements of fantasy and science fiction, and wit and humour. 
The book's publication was at first forbidden in the Soviet Union. It circulated in samizdat until it was officially released in the country in 1987. It is "one of novelist Mikhail Bulgakov's most beloved stories" featuring a stray dog "named Sharik, who takes human form" as a slovenly but self-important New Soviet Man. The dog's internal monologue at the start, grumbling at his life in the city, sets the scene for the novel.
Plot.
Moscow, 1924.
After a terrible day, a stray dog thinks about his bad luck to live on the streets of Moscow. Then, to his surprise, successful surgeon Filip Filippovich Preobrazhensky arrives and offers the dog a piece of sausage. Overjoyed, the dog follows Filip back to his flat, where he is given a stock dog name, Sharik.
At the house, Sharik gets to know Dr. Preobrazhensky's household, which includes Doctor Bormenthal, Professor's student and protegé and two female servants. Despite the Professor's vocal anti-communism, his frequent medical treatment of the Party leaders makes him untouchable. He refuses to reduce the size of his seven-room flat, and treats the Bolsheviks on the housing committee with contempt. Impressed by his new master, Sharik slips easily into the role of "a gentleman's dog".
After Sharik's health improves, the Professor prepares to operate on him. Sharik is dragged by the scruff of the neck into the lab. There, he is sedated and an operation begins. As Bormenthal assists, the Professor gives him a human pituitary gland and human testicles. 
During the weeks after the operation, the household is stunned as Sharik begins transforming into an incredibly unkempt human. In the aftermath, the Professor and Bormenthal patiently attempt to teach Sharikov basic etiquette. Instead, Sharikov mocks the idea of manners as relics of Tsarism. He insists that it is better to behave, as he puts it, "naturally". As a result, Sharikov curses in front of women, refuses to shave, and dresses like a slob.
Meanwhile, Sharikov turns the Professor's life into a living hell. He is caught attempting to rape one of the female servants. Enraged, Bormenthal beats Sharikov up and forces him to apologize. Infuriated, Sharikov leaves the apartment and remains gone for several days.
Later, Bormenthal begs the Professor for permission to dose Sharikov with arsenic, calling him a man with "the heart of a dog". The Professor is horrified and orders Bormenthal not to "slander the dog". He explains that the human body parts, which came from a drunk, are responsible for all of Sharikov's defects. Bormenthal then suggests that they redo the operation, using the body of a genius. Again the Professor refuses, explaining that the operation was meant to improve the human race. Breaking with his former beliefs, the Professor admits that any peasant woman could give birth to a genius and that eugenics are a waste of time. In conclusion, the Professor refuses to permit Sharikov's murder or to undo the operation, which could easily kill him as well.
Soon after, Sharikov returns, explaining that he has been granted a job by the Soviet State. He now spends his work-day strangling vagrant cats, whose fur is used to imitate that of squirrels. Soon after Sharikov brings home a female co-worker, whom he introduces to the Professor as his new common law wife. 
Instead of giving them their own room, as Sharikov demands, the Professor takes the woman aside and explains that Sharikov is the product of a lab experiment gone horribly wrong. The woman, who had believed that Sharikov was a Red Army veteran wounded during the Russian Civil War, leaves the apartment in tears. Seething with hatred, Sharikov threatens to fire her. Again Bormenthal beats Sharikov up and makes him promise not to do anything of the sort.
The following day, a senior Party official arrives and tells the Professor that Sharikov has denounced him to the secret police, the Cheka. Explaining that nothing is going to happen to him due to the State's distrust of Sharikov, the Party official departs. When Sharikov returns, the Professor and Bormenthal order him to leave the flat permanently. Instead, Sharikov refuses and draws a revolver. Enraged, the Professor and Bormenthal pounce upon him. 
That night, an ominous silence reigns in the flat and the lights are left on for many hours after bedtime. Over the days that follow, the Professor and Bormenthal look far more relaxed than at any time before Sharikov's arrival. Eventually, the police arrive with a search warrant. They demand to see Sharikov. Unintimidated, the Professor orders Bormenthal to summon Sharikov, who is slowly being transformed back into a dog. The Professor explains the change as a natural phenomenon, although it is obvious to the reader that in fact he and Bormenthal have simply performed the reverse operation. The police depart.
In the aftermath, the fully canine Sharik blissfully resumes his status as a gentleman's dog. However, he is soon terrified to see the Professor bringing home a human brain and removing the pituitary gland...