Yesterday (May 19th, 2017) Iditarod board :In the 4-3 vote, decided that mushers can only carry dogs in front of their racing sleds' handlebars, so they can see the dogs at all times.
The Iditarod Board of Directors imposed looser restrictions on hauling dogs before the 2017 Iditarod, citing safety concerns. They tweaked rule language so mushers could only carry dogs in their front sleds and forbade them from carrying the dogs in caboose-like kennels hooked to the back of their racing sleds, a strategy spearheaded by four-time Iditarod champion Jeff King. In response to the controversial rule change, the 2017 Iditarod saw a tiny wave of high-tech sleds from mushers, including the Seaveys, that incorporated space to haul dogs both in front of the handlebars and in boxes on the back of the sled runners, behind where the musher would stand. Under the new rules, those sleds are forbidden.
Information taken form the Alaskan Dispatch.