Screaming or howling in Mills County, Texas

It happened on November 17, 2007. My family and I were hunting on a family friends ranch in Goldthwaite. It was mid afternoon, and we were taking turns riding horses. When it came my turn to ride, my sister-in-law joined me on another horse. The horses were giving a lot of attitude, and not willing to comply with our requests of direction. So we were having to spin them and kick them cause they didnt want to leave the coral area. But once I got mine to leave then my sister-in-law's followed. We walked off and a couple hundred yards away, the coral disappeared. She and I were just admiring the land and talking. I then noticed that there were no animals around, and there wasnt any animal sounds either, birds included. All I could hear was the footsteps of the horses, and she and I talking. Right about then, there was a strong odor of a dirty wet dog, and the horses started acting different. Their ears kept perking up, and then moving back. I really didnt think anything of it at the time cause I was joking with my sister and we both started laughing. Right about then both our horses jumped like something had startled them, which made my sister jump and let out a small scream. I turned around in the saddle and looked back and to the left of where we were about 10 feet away to see two pine trees shaking bad. The two trees had grown close enough to each other as to have their branches interwoven so you couldnt see in between them. They were tall trees about 10 feet tall. It was as if something had grabbed the branches about 5 to 6 feet up and was shaking them which in turn was making both of the trees shake from top to trunk. I didnt say anything to my sister-in-law about it cause I didnt want to startle her. We continued on for a little bit, then we turned around and headed back to the coral. I never saw anything. They have cattle, goats, and horses on their land. There is also deer, turkey, and he occasional hog, bobcat, and mountain lion. I am 32 and I have been hunting most of my life, and I have never seen or experienced anything like that before. I have smelled that odor before, but I have never thought anything of it.