A method for training an animal to detect a condition such as cancer in a human or animal individual. A training sample is presented to the animal to be trained where the training sample is a gaseous sample or vapor generated by a cell population associated with the predetermined condition. The population of cells associated with the predetermined condition may be for example a culture of an established cell line associated with the predetermined condition. Simultaneously with or subsequent to presentation of the training sample the animal is subjected to an adverse stimulus such as an electric shock. The animal is allowed animal to perform a first predetermined response in order to avoid escape or terminate the adverse stimulus. The invention also provides a method for detecting a condition such as cancer in an individual in which a trained animal performs the predetermined response upon exposure to vapors from a body fluid of an individual affected with the condition.
