Untitled Sighting

My wife took our dogs outside this morning like she always does around 6:30am. She was standing on the deck and the dogs were in the fences in yard. She heard an odd unfamiliar creepy moan sound and she was still blurry from just waking up, she swears it was a really big black thing. It walked out from behind one tree into or behind a brush area where she couldn't see it. It was then silent and she couldn't see it. She said it was big like a horse but not a horse. Listen, my wife isn't the type to believe in any of this. But she is freaked out. She brought the dogs in, locked the door and closed the curtains. She is really spooked. It's very unlike her. She said it was one moan then a short little one. A sound she never head before. It was maybe 40-50 feet from our backyard fence. That is very dense and wooded for many acres. I went into that area about 30 minutes later and didn't see anything, couldn't spot prints or anything. Two years ago I was on the deck also letting the dogs out in the winter time and when the wind blew I caught a wiff of a very strong foul odor like a wet animal or something but I had no idea what it was.