I am a 35 year old man who lives alone in a secluded cabin in the woods. I am 6'1" with blond hair and blue eyes. I have never had a problem bringing ladies home. I am a Veterinarian and have an office in the city. I also do volunteer work at a dog shelter on the weekends. The owners rescue dogs and find homes for them once I have examined them. Some come in pretty bad shape so they take a little longer to heal. Others are beautiful dogs that were simply abandoned somewhere. The nearest neighbor lives 15 miles away on a farm. I met them when I bought the cabin I am living in from them 2 years ago. They are a retired couple named Jim and Barbara. An incident happened to me when I met them. They had several dogs and other animals on their farm. As I walked around their property one of their dogs was following me. Since they had already assured me that none of their dogs was vicious, I didn't mind his company. However, as I was walking I was suddenly knocked to the ground by this dog. He was big but I didn't recognize the breed. I thought he just wanted to play. But as I was getting up I saw the dog had his cock hanging out. It was huge. This dog seemed horny and I was the only bitch he could see. I got up and started walking back to the farmhouse with the dog still following me. I picked up the pace when I was suddenly knocked to the ground again. As I fell the dog jumped up on my back and started humping me. I was terrified. As I tried to get up the dog growled so I remained still. The dog kept humping me until he appeared to cum on my pants. I don't know why but I got a hard-on. The dog got off me and I quickly got up and headed back to the farmhouse. The dog followed me with his cock still hanging down. By the time I got back to the farmhouse the dog's cock had retreated to its sheath. I would've been embarassed otherwise because I don't know what Jim and Barbara would've thought. I made the deal with them to buy the cabin and moved in 2 weeks later. While working at the shelter one day, I was examining a boxer that was rescued. He was a beautiful dog. I don't know why anyone would get rid of it. Anyway as I was examining it, I noticed his cock peaking out of its sheath. I backed away sort of startled. I then wondered if the dog had been neutered or not. At the same time my mind drifted back to the incident with the dog at the farm. As I thought about it I got a hard-on. I can't believe I was getting hard thinking about a dog fucking me. It almost seems like the boxer was aware of my condition because more cock came out of his sheath. No one was at the shelter but me so I unzipped my pants and pulled my cock out. I began to masturbate thinking about the dog on the farm fucking me, all the while looking at the boxer's cock. The boxer suddenly jumped off the examining table and came up to me. That scared me and I quit masturbating. I still had my cock out and the boxer came up to me and sniffed at my cock which began to throb and bounce. The boxer then licked my cock and I almost came. As the dog licked I got back to thinking about the dog on the farm dry humping me. I felt I was ready to cum when the dog stopped licking me and walked behind me. Being as horny as I felt I quickly slipped my pants and underwear off and instinctively dropped to my hands and knees. The boxer sniffed at my ass. My cock was throbbing and bouncing wildly. Suddenly the boxer jumped up on my back and gripped me as he started humping. I was so excited that precum leaked from my cock. I wanted the dog cock inside me. I have never had anal sex but this perverse feeling dominated my thoughts and I wanted to be fucked in the ass. I suddenly felt the boxer enter my asshole. As he did he gripped me tighter and lunged forward fucking me at an incredible pace. I shot my cum as he penetrated me. My cock was still hard as he continued to fuck me and although it hurt when he entered me I was loving it. It felt so natural. As I was enjoying the fucking I felt the dog grip me tighter and something enter my ass. I realized he had just slipped his knot in me. As it swelled up inside me my cock began to leak cum again. The dog then quit humping as I felt his cum fill my ass. I leaked out more cum when I felt this. The dog emptied his cum inside my ass and stayed tied for about 15 minutes. I can't believe this actually happened. After the dog pulled out I felt empty. I looked back at the boxer who was licking his cock clean. It must've been at least 8 inches long. The knot slipping inside me must make it feel like having a good 12 inches of cock in there. A bunch of thoughts were running wildly in my brain as I had the urge to be fucked again. Realizing I was at a dog shelter I could check to see if I could interest any other dogs. Now that I think of it there was a lot of barking going on while the boxer was fucking me. The other dogs must've smelled sex and got excited also. I walked around the clinic looking for male dogs. I saw a few small ones and they had their cocks peeking out of their sheaths. I then saw a rottweiler who was licking his cock peeking out of its sheath. He would do. I still had my pants off so I let him out of his cage to see what he would do. He walked behind me and jumped up on my back knocking me to the floor. I fell to my hands and knees and the rottweiler quickly mounted me. My cock was already hard again. As the dog started humping I moved in an effort to help him find my asshole. He found the mark and quickly thrust forward gripping me as he started to fuck me. I leaked precum and started pushing back meeting his every thrust. My cock was on fire wanting release. I started mumbling: "oh fuck me...fuck fuck fuck...oh yeah...give me all you got...fuck me deep...give me your knot...make me your bitch". I then felt the dog grip me tighter as I felt his knot slip inside me. I started pushing back hard as I felt the knot swell up. "fuck me...cum inside me...I want all your cum". I then felt the dog give a couple more thrusts then felt the warm cum filling my ass. Cum started leaking out of of my ass dripping down. It must've still been full from the boxer's cum. I was still pushing back as I felt the cum still pouring in my ass. I didn't want to stop when I suddenly shot a load of cum. "Oooooooooooo yessssssssssss"! That has to be one of the best climaxes of my life. About 20 minutes later the rottweiler pulled out. Once again I felt so empty. But I was pretty exhausted. I then saw the boxer whose cock was hanging out. I forgot I didn't put him in a cage. He walked up behind me. "I guess you want seconds". Smartly though I got the rottweiler and put him back in his cage. The boxer followed me so I dropped down on my hands and knees in front of the rottweiler's cage. The boxer quickly mounted me and quickly penetrated me. My cock got hard again. I was too tired to push back so I just stayed in position and took another pounding. I could hear all the barking again. The boxer was fucking me at a furious pace. It felt so good as I just felt every thrust. The boxer gripped me tighter and lunged forward slipping his knot in me. I couldn't believe I shot a third load in less than an hour. I was still dripping cum when I felt the boxer cum inside me for a second time. He only stayed tied with me for 10 minutes this time. As he pulled out cum leaked out of me dripping down my legs. My ass was filled with three cum loads. I could not believe this happened but I loved it. I got up and went to wash up. Then I put my pants back on and went home. I am surely going to enjoy this job a hell of a lot more now. I hope they rescue a great dane cause I would love to feel his cock and knot deep inside me.