You folks are lucky to have grown up with the internet. When I was first feeling the urge to breed mares, my only "porn" was the popular cowboy movies! Being a city boy, I settled on a beautiful collie girl for my first lover and she was all in on the idea. But mares were my big turn on. Then, in college, I discovered a riding stable at a nearby resort. I went there with no knowledge if what I wanted to do was even possible! I had ridden horses but only in a public setting, so I had never touched them.
The kid running the place asked me what I wanted. I saw a mare standing there who seemed to be winking her pussy, and pointed to her. The guy said, "Yeah, she has a great pussy." I didn't expect such a blunt assessment, and was speechless! I rode her high on the mountain and found a point in the trail that went over a series of slate steps that looked perfect. I climbed down, with her butt just past one of these steps, holding the reins as I walked behind her. Her tail was slightly elevated, and when I pulled it aside she started winking again. Looking back, I realize she was no virgin to men as well as being in heat.
The attraction was overwhelming. I HAD to mate with her even if it killed me. To my utter amazement, she let me do whatever I wished and that soon led to me losing my load in her. As I pulled out, I was alarmed to see my cum following my cock in a long thick stream. Scared of this happening when I returned her, I used some dry leaves to remove the evidence.
I had never seen myself as going down a life long path, I just saw it as a one time itch that I wanted to scratch. Remember, as far as I knew, I was the only zoo in the world. But that experience would remain the defining moment of my life. I dated and had relations with several women, expecting that would be even better, but somehow it never seemed like what I really wanted. It was probably the aftermath of the human sex that made me realize I was a dyed in the wool horse fucker!