The Kennel Murder Case is a 1933 Michael Curtiz film based on the novel with the same name. It stars William Powell, Mary Astor, Eugene Pallette and Ralph Morgan.
The Internet Archive has this online:
at about 28 minutes in: "I'm a doctor, not a magician."
and then at about 28:55: "I'm a doctor, not a detective."
and at about 59:10 the doctor says, "I'm the city butcher, not a detective."
The New York Times has a positive review, as do Variety and Time Out. TCM has an overview.