Dolphin-Assisted Therapy (DAT) is an increasingly popular choice of treatment for illness and developmental disabilities by providing participants with the opportunity to swim or interact with live captive dolphins. Two reviews of DAT (Marino and Lilienfeld  and Humphries ) concluded that there is no credible scientific evidence for the effectiveness of this intervention. In this paper, we offer an update of the methodological status of DAT by reviewing five peer-reviewed DAT studies published in the last eight years. We found that all five studies were methodologically flawed and plagued by several threats to both internal and construct validity. We conclude that nearly a decade following our initial review, there remains no compelling evidence that DAT is a legitimate therapy or that it affords any more than fleeting improvements in mood.
Marino, L., & Lilienfeld, S. O. (2007). Dolphin-assisted therapy: More flawed data and more flawed conclusions. Anthrozoos: A Multidisciplinary Journal of The Interactions of People & Animals, 20(3), 239-249.