The range in size seen in dogs is quite extraordinary. This report in Science (subscription needed to get past Abstract) descibes the genetic basis of this variation. You can read a BBC summary here.

Article from Current Biology, reporting a correlation between amplitude of tail wagging and the nature of a visual stimulus (high amplitude – owner, medium – unknown human, and very low -cat). Intriguingly, this effect was always seen on the right hand side of the dog’s body “this pattern of results fits with the general hypothesis that there is a fundamental asymmetry in the control of functions related to emotion” say the authors. The dog owners amongst you can decide whether this is interesting or trivial.

While we’re on the subject of dog handedness, check out my article on exactly this subject, written with a final year project student. The dog owners amongst you can decide blah blah.