Andrew Dickerson, a Mechanical Engineering graduate student at Georgia Tech, has pioneered information regarding the shaking frequency for an animal to optimally dry its skin. 

The process consisted of measuring the shaking frequency of a Labrador retriever, which turned out to be about 4.3 hertz.  Next they created a simple mathematical model and some assumptions about the force holding the water to the dog.  For the water to be ejected, the dog must create a centripetal force greater than the adhesion force of the water. 

Next, the frequency was scaled to Radius^.5, which means smaller animals would need to shake faster than larger animals.  A mouse shakes at about 27 hertz while a bear shakes at only 4 hertz.  This data revealed a scaled dependence of Radius^.75.  It was also stated that as animals get larger, they seem to approach 4 hertz.