Contact paper! That probably sounds weird, but you can actually purchase stained glass or frosted privacy paper for windows. This will prevent your dog from being able to see anything out the windows and he/she will lose interest. I purchased some of this from HD the other day and, though I haven't used it yet, I am able to tell you they have many different patterns, from simple frost to rippled glass to stained glass, so you would probably be able to find something you liked. Good luck!

P.S. Make sure you're using the stuff made for windows, not shelves. The adhesive for shelves is way different than for glass.