 SPOILER: In the beginning of the movie we "meet" Doctor Pavlov in  the prison Cruella is. He is obviously named after the Russian  physiologist Ivan Pavlov who is renowned for his landmark study on  conditioning, using dogs as test subjects. In Pavlovs experiments,  a dog was taught to expect a morsel of food whenever it heard a bell  ring, hence the joke that Cruellas "cure" is reversed when she  hears the bell toll of Big Ben.