One of the classes I had this quarter was Clinical Assessment where we studied different psychological disorders. One that caught my attention was Tic disorders. A Tic Disorder is diagnosed when either motor (Rapid, recurrent movement of the arms, legs, or other areas) or vocal (Vocalizations) grunts, abdominal or diaphragmatic contractions, but not both, are experienced persistently.
While the DSM IV is used to diagnose humans; it may serve to diagnose animals as well because I believe animals have their own “personality,” and as humans they also can develop certain disorders.
Cinnamon is one example. Ever since she was a puppy she's got rapid motor contractions which are called “tics.” These tics occur many times a day and nearly every day, but they do not seem to bother her or impair any areas of her functioning . They are not effect of substance abuse (not that I know) or a general medical condition.
Here is a video showing her Tics: