I just saw this online - looks pretty good but a bit pricey (not sure if you can turn the tracking mode off when not needed). I just skimmed through the article but thought others might be interested:
http://www.cnet.com/news/whistle-bringing-gps-to-second-generation-dog-wearable/
http://www.cnet.com/news/whistle-bringing-gps-to-second-generation-dog-wearable/