I feel really unclean for having googled this, but you will be delighted to know that the dog will be fine.

http://www.tmz.com/2010/08/17/dr-frank-ryan-dog-jill-border-...

Re OP: my county has recently banned electronic devices while driving (only hands-free calling allowed), and completely anecdotally it has seemed to make a difference, although it's hard to say whether it is a temporary effect.

The geek in me is also thinking "how can it be proven that he drove off while actually twittering" but I am trying not to go there - it's besides the point.