Investigators also learned the injured dog was often out of its yard, which was reportedly verified by several independent sources, according to Monday's news release.
According to the incident report, the man who lived in the trailer told deputies he finished a cigarette at around 12:15 a.m. and tossed the burning butt into a plastic coffee can which was about a quarter full of old cigarette butts.
The Wyoming Highway Patrol temporarily closed Interstate 90 about 12 miles north of Buffalo after a commercial trailer caught fire on Saturday afternoon, according to a prepared statement from Patrol Sgt. David Wagener.
No human injuries were reported at a trailer fire west of Casper on Wednesday afternoon, but several dogs may be hurt, a Natrona County Fire Protection District spokesman said.