I was 16 when I had my first experience of being fucked by a dog. After that first time, I had a lot of chances to experience K9 sex, mostly with dogs that had not been trained to fuck people or dogs whose owner had trained them, but they really did not have much experience. Having sex with these dogs gave me the opportunity to learn how to get a dog to fuck me, even if the dog had never fucked a person before. 

  During my first year of college, just after my 18th Birthday, I was spending a weekend with a 39 year old fuck buddy. I got to his place Friday evening and we fucked most of the night, before getting any sleep. We had sex again late Saturday morning after we both woke, and again around noon. I expected the sex to continue most of the afternoon and evening, but my fuck buddy was more interested in watching sports on television. 

  I was disappointed and still so horny that I was frustrated. During a break between televised games he decided to run out to a store to pick up beer and a few other items, leaving me alone, except for his Doberman. He had hardly walked out the door when I decided the dog was going to help me with my frustrations. 

  I sat on the floor and called the Doberman over to me. I was practically naked, with just a short wrap-around robe on. I got the dog to lay his head in my lap as I began to pet him. It was not long before one of my hands was gently rubbing his cock's sheath. I think it only took a few seconds for the tip of his cock to begin peeking out of the sheath, and his nose seemed to be inching closer to my wet pussy. I continued rubbing the sheath for a couple more minutes, until a couple inches of cock were exposed. Then I shifted our positions so I could get my mouth to his cock while continuing to rub the sheath. 

  The Doberman's cock stretched out of its sheath quickly once my lips and tongue touched it. Within a few minutes the knot was exposed. I did not waste any time. I got on my knees and got the dog to stand behind me, between my legs. Reaching behind me, I took hold of his front legs and lifted him up, pulling him forward so the legs straddled me. Setting his chest on my back, I reached between my legs with one hand and guided the tip of his dick to my pussy. The feeling of my warm, wet hole was all the encouragement the dog needed. As soon as his cock tip pierced my pussy's lips, he started humping. 

  Like any dog, his humping was fast and a bit wild, but that only added to the thrill I was receiving as his dick stabbed around inside of me. That boney tip kept hitting and slipping over different parts of my vagina, stimulating each spot. It took a few minutes before his knot began smacking against my labia. I wanted that knot, however as long as his cock was doing what it was doing, I was willing to wait. My pussy was getting wetter and I could feel some of my juices beginning to ooze out. 

  Those juices were lubricating me and his knot. After just hitting against me a few times, the knot slipped between my labia a couple of times, then it slipped into me. I moaned. It felt wonderful, spreading me open and for a moment, making me feel full. It slid out, but a second later it was in me again. That swelling knot must have slipped in and out of me a half dozen times or more and each time it was bigger and stretched me more. It finally seemed to swell too big to escape. The Doberman pushed it deeper. On the third hump after it had seemed too large, it slipped back out. The next couple of humps only forced it between my labia. I was afraid the chance to be knotted was lost. 

  Another thrust pushed the knot into me again. It seemed to rip my pussy open. I screamed as the pleasurable pain ran through me. I doubt my scream excited the Doberman like it would have a man, but he seemed to thrust harder a couple of times. The knot had locked, and to be sure, I squeezed my pussy around it. The dog stopped humping. 

  With the knot tightly wedged just inside my pussy, its throbbing as blood engorged his dick was exquisite. There was no end to my moans. I could feel his cock stretching deeper and growing fatter within me. As much as I loved the humping, I was loving the throbbing and the enlarging of him even more. An orgasm was already beginning to build within me. 

  The Doberman's dick began pressing against my cervix. That was enough to send that first orgasm racing through me. I shuddered and moaned even louder. It seemed like that cock was going to continue growing forever. My pussy was feeling full and stretched. The throbbing was making my muscles twitch and my pussy repeatedly squeeze around the cock involuntarily. It only happens occasionally, but it happened with the Doberman, the tip of his dick began piercing my cervix. My body bucked. I squealed with pleasure. 

  As if on cue, the throbbing of his cock grew stronger. It was no longer being filled with blood. Now it was pumping his sperm towards my open womb. As his hot cum gushed into me another orgasm tore through me. I screamed and my body shook violently. As more cum squirted into me, I continued to scream. Minutes passed. My womb filled with cum. I could feel it leaking pass my cervix and into my vagina. My head was filled with ecstasy. 

  I have no idea how long the dog remained knotted in me. He seemed to be pumping cum into me for a very long time, though I would have loved having it last even longer. From the moment that first stream of hot cum erupted in my womb, I became oblivious to everything else. Therefore, I have no idea how long my friend had been watching and listening. 

  However, when the Doberman's knot slipped from my cunt and he moved away, I heard him. "You like dog cock do you? You dirty slut!" 

  Almost before his words faded from the air, he was behind me, ramming his cock into my pussy. He fucked me deep and hard, slapping my ass during just about every stroke, and calling me his nasty slut. I loved it and the hours of fucking and sucking that followed, including another fucking by the Doberman.