Steven Romero, 37, of Fruita, was arrested for the incident on Thursday while he was in court on unrelated matters, The Denver Post reported.
The German Shepherd mix named Buddy was discovered near Grand Junction on a snowy road with a rope tied around its neck on Wednesday, the Post reported.
A Facebook page entitled, "Demand Justice for Buddy" was created by animal activists and has been visited by 1,120 people who want to convince a Colorado court to sentence Romero, if he is found guilty, to the maximum three years in federal prison, one year of probation, and a $100,000 fine, the Post reported.
"Our hearts go out to the dog. We want to make sure the person who did this serves every minute in jail that he can get, said Betsy Gunderson of Stuart, Fla.