According to a new study by a Colorado State University associate professor, dogs in animal shelters were less likely to bark and more likely to sleep to classical music than heavy metal.Lori Kogan, who is in the College Of Veterinary Medicine And Biomedical Sciences and a licensed psychologist, played different music within at a shelter over the course of four months and recorded their responses. The investigated genres included classical, heavy metal and a simplistic psychoacoustic classical composition marketed specifically for dog relaxation. Kogan's study suggests that heavy metal induces more nervous shaking in dogs. Playing classical music appeared to calm dogs more than other music selections or no music at all, according to the study, which appears in a recent issue of the Journal Of Veterinary Behavior. The study suggests that shelters refrain from playing heavy metal music because of the detrimental impact it may have on dogs' stress and anxiety levels. Read more from ColoState.edu.