The thing on its back is called a surcingle, and you're correct that it has a handle that is not a standard piece of horse equipment. What's on its head though is just a halter, and it's a totally standard issue one that could be used by anyone of any height. It's just a way to control horses while on foot without putting a bit in their mouth like a bridle.
Example of a standard surcingle (they never have stirrups, it's for work without a rider): http://www.amazon.com/Tough-1-Miniature-Horse-Training-Surcingle/dp/B002HI78JO
Mini horse halter: http://www.amazon.com/Weaver-Leather-Miniature-Horse-Halter/dp/B002WVF8HA
Guide horses wearing similar surcingles to the one in OP's picture: http://www.guidehorse.com/