Untitled Sighting

My teenage son is a night owl and was awake in his bedroom late one night/early one morning.  Approximately 2 or 3 am, he heard what he described as a "metal scraping on wood" sound outside his bedroom window.  He then heard several inhalations/exhalations as if something was sniffing at the window followed by a loud grunt.  He described this sound as "buck snort" or someone clearing their throat.  We have 3 little dogs in a pen right by his window and he reported that the dogs were not barking which is odd because they usually bark at everything!!  He immediately got out of bed and spent the rest of the night on the couch.  He wouldn't sleep for several nights following this incident.  He told me about it the next morning.  When I got home from work that afternoon, I went around to his window to investigate.  The window was open approximately 1-2 inches.  We have casement type windows and he had rolled them in but not latched them so they could have been opened from the outside but it would have taken some effort.  We live near a major highway so I immediately thought that it might be a vagrant trying to break in.  2 days later, I returned home from shopping around dusk and found the door on a camping trailer we had on the property had been opened.  No one was in the trailer and nothing appeared to have been tampered with.  The metal that my husband had wedged in the door to latch it was on the ground right by the steps.  The wind wasn't blowing that day so we know it didn't blow open.