I wonder if this is covered by existing traffic laws? How would the cops persuade your Rottie to blow in the RBT device without taking half an arm off? Would they need to display C plates (canine)?
The pooch would have to pass the knowledge test, complete 12 months of log books, , then the practical test, to get a license.
Also you can't sit the knowledge test until you're 16, by which point most dogs would be dead or very close.
I know I know, using logic and reason when only humour was intended, sorry...