Untitled Sighting

Hiking with a companion and two german shepards around 9 am in the Rogue-Umpqua Wilderness. Saw a large brown object moving fast through the understory, which was quite thick. Dogs chased the object, both dogs had saddlepacks, one dog had a tarp which was securly rolled and tied on the middle of his back. Dogs were gone about 3-5 minutes and came running back. One dog which had the tarp on returned and continued to run past us and ended up at the shelter, about 1 mile back where we had stayed the night and was extremely scared. The other older dogs stopped when encountering us and listened when we told it to stop but was also very scared. Several things were unusual, the intense musty smell, something like a bull elk in heat but not or not like a bear either. The dogs fear as they have chased bears, coyotes, deer ,elk and are never scared upon return. The tallness of the object as it was way too tall for a bear or elk. Too quiet for an elk also. The untied tarp which was securely tied but upon return of the chase the tarp was tied but just one knot. I tie good knots!