I think ER brought the items during the first 24 hours. An article from November 21st:
http://www.thedenverchannel.com/news/western-slope/la-plata-county-officials-search-for-13-year-old-dylan-redwine-whos-been-missing-since-monday
Members of La Plata County Search & Rescue team using bloodhounds searched for the teen Monday night and Tuesday. The search area included the shoreline around Vallecito Lake, several small subdivisions, county roads, steep wooded hillsides and hiking trails. Many of the homes in the area are seasonal while some are occupied year around.
These bloodhounds were tracking dogs. The cadaver dogs were used at the lake, in boats. (Can't find the link now.)
Around Christmas, LE brought a bloodhound from New Mexico to try to track Dylan, saying that they can follow a scent for up to six weeks after the fact. The dog didn't find a scent.
http://durangoherald.com/article/20121226/NEWS01/121229694/
In a recent development, a bloodhound from New Mexico searched the same areas in Vellacito gone over earlier by search teams and dogs, KOAT-TV in Albuquerque reported.
The bloodhound, the station report said, can detect a scent up to 6 weeks old. But the dog turned up nothing.
So, lots of dogs, but no luck. MR says he believes Dylan isn't in the area anymore.