So you want to take your spouse AND you dog on your motorcycle ? Sidecars aren't your thing ? Well, here's your solution, the Open Road Outfitters WAGS Pet Trailer.
Just buy one of these trailers (US$ 3,095+), put your dog/cat/rabbit/SWMBO in it, and off you go.
The trailer comes with a spare tire, lights, inside carpet and even mud flaps (your motorcycles probably doesn't even have these..) You've also got tons of optional extras, like chrome, graphics and cooler (what ?? no airco ??).
Check out the other nifty motorcycle trailers from Open Road Outfitters. They have cargo trailers, and even camping trailers. This way you can make a train; 3 trailers behind your motorcycle.
http://www.openroadoutfitters.com/trailers/pet_trailers.cfm?CFID=3411&CFTOKEN=53682309