If you look at the experimental design for some of those studies, one of them involved opening up a dog's chest, attaching a pacemaker to the heart to simulate tachycardia, and then pumping various drugs into the dog to see if any slowed down the heart rate... which surprise surprise, none did because drugs don't stop a pacemaker. That one alone involved around 30 dogs. The experimental design was inherently flawed and it puzzles me how the proposal made it past the university's ethics board.