According to the article, the man forgot that the dog was tethered to the bumper of his truck and he was in a rush to get to an alcohol class. Several people were witness to the gruesome scene of animal torture and contacted the authorities when they saw a dog dragging on Highway 160 in Alamosa County on January 6 of this year. This case of cruelty and neglect must not be overseen by the law and he should be charged according to the state of Colorado.

At a certain point of his journey he realized that the dog was tethered to the bumper and placed the dogs mangled body in the truck's back bed.  According to authorities, the body of the dog was skinned nearly to the bone.

http://www.kwgn.com/news/kdvr-man-forgets-dog-tied-to-bumper-drags-it-on-highway-20120119,0,2930488.story