I am heading up the bush for a week soon with the two JRs, Spot and Tiny. Tiny is now 17, has slowed down a fair bit and has failing eyesight and hearing, so that she gets left behind a bit. She still has a good nose, so she is not going to get lost permanently. As she cannot hear me call, she can be a bit hard to find, so I decided I would buy one (actually three – for US$59!) of these: https://buy.thetrackr.com/ to help me find her.
They work off Bluetooth and are connected via an App to your phone, so that you can make them sound a beep when you are looking for them &/or your phone can also indicate direction/distance. If you are somewhere the phone will actually work, they also have many other useful features too numerous to mention. They can utilize the SMS service, for example. They would also be great for keeping track of small children, motor cars, keys, etc.
Update: For my purposes the Trackr is no better than nothing. All it tells me is that Tiny is in range, but not what direction she is in. The audible signal is completely impossible to hear more than approx 2 metres away – even for someone who has good hearing. For me they were a waste of money. I only hope the new versions are better.
At the moment they only have a range of 30-50 metres, but that is better than nothing (especially when I am deaf too!) Soon there will be a new Bluetooth Standard: Bluetooth 5 will have four times the range and twice the speed of Bluetooth 4.2: http://www.pcworld.idg.com.au/article/606609/faster-longer-range-bluetooth-5-reach-devices-soon/ which will have a working range of 120 metres and a maximum range of 400. This will make such devices really useful.
Of course the dogs have their own Tyvek raincoats (http://www.theultralighthiker.com/tyvek-jack-russell-rain-coat-13-grams/), down beds, groundsheets, ultra light bowls, dehydrated mince, Smackos & etc, etc. So far they have not been called upon to carry any of this gear (They are busy pointing out the deer!), but I could construct little packs for them I suppose. These ;little guys are so small I have to portage them across rivers as they would be swept away. I carry Tiny in an ultralight day pack worn pack to front (http://www.theultralighthiker.com/osprey-ultralight-stuff-pack/), Spot has mastered a trick of riding on my shoulders, like this: