(c) 2015 by Domino
Also known by the title “Four Year Old Bull Mastiff”

I first saw him across the street from my house, he lived in the apartment. I stared at his huge ball sack as he walked by. I started making a fuss over him and going over to pet him when he was brought out. I followed the schedule of his owner, making sure we’d meet at least 2-3 times a week. I saw that he worked pretty long hours and finally asked if he’d like me to at least let him out for him and he jumped at the chance.

I walked him a few times, with the owner, because he was so big, but, like most big dogs, he just ambled along and I tried not to stare at his shifting ball sack, bigger than any man’s I’d seen. We joked about his size and walked by a vet’s office, where we took him in and had him weighed, 154 pounds. I’m 98 pounds. My pussy twitched at the thought of him mounting me.

I also acted rather ‘grossed out’ about his huge sack, and his owner just laughed and said that he was a stud dog, otherwise, he’d have had him fixed. I joked right back that he should buy him some underwear when he was out getting walked, not wanting him to suspect my true motives.

He gave me a key to his place and the first day, I went over to get him wearing a long sun dress, nothing on underneath. I was actually panting when I led him up to my house. I’d made sure all the blinds were pulled and I’d checked his height many times and I’d purchased a leather bench ottoman. I’d also attached a leash to one of the door handles, so he’d be unable to back up, if I was lucky enough to have him fuck me.

I looked at his huge ball sack, as I followed behind him and, at the thought that maybe I’d have that cum shooting into my pussy that day, I felt a drop of cum actually roll down my inner thigh at the idea.

We entered the house and when I went to remove his lead, his head turned, I saw his nose flare and his ears pricked up. Panting, I stepped out of the sun dress, and stood in front of him, naked, with the drop of cum rolling down the inside of my thigh. His nose flared again and suddenly, he just shoved his nose between my legs! I moaned and leaned back against the door, spreading my legs for him. He licked me with his huge tongue and I shuddered.

I’d done some research, and found out that most dogs love the taste of pussy but don’t seem to figure out where it ‘comes from’ and will repeatedly lick AT your hole, looking for more, but that’s about it. So when his tongue actually penetrated me, I gasped and came hard on his tongue, now pumping in and out of my pussy.

Moaning and panting, I fell forward, onto the stairs and bucked my hips wildly as he groaned and shoved his tongue inside me as far as it would go. It was like being fucked by a snake, it rolled around inside me and I came over and over again. His breathing became very ragged and I felt his head moving in a different way and glanced behind me at him and saw that he was pumping the air with his hips.

That was the first time I actually saw his cock and, just looking at it made me blow all over his thrusting tongue again, it was bright red and had a lot of veins, and there were long runners of his sticky pre-cum dripping down from the tip of it. It was kind of bobbing in mid-air and, as I watched, I saw it shoot a small amount of dog slime out.

He was more than ready for me, but he was still frantically eating me out, he must have really liked the taste. Panting like I’d just run a marathon, I stood up off the stairs, where I’d been bent over, doggie style while he tongue fucked me.

I watched him standing there, panting very loudly, his dog meat hanging out, already about 9 inches long and very wide. Moaning, I went into the darkened living room and he followed me, also gasping with excitement.

I laid down on the far end of the leather ottoman, making him come towards the wall and he drove his tongue right back inside my pussy. Moaning, I attached the leash hanging from the door knob to his collar and quickly shot under him on the narrow bench. It was perfect, narrow enough that he could straddle it and low enough that I was at the perfect height for him to enter me.

Unlike what I’d read about some other dogs, his cock found my cunt very quickly. After only a few pokes around, his cock penetrated me and he did something VERY hot..after the head of his cock entered me, he paused, just like a man would and I groaned, listening to his heavy breathing.

I was just about to push myself down on his shaft, moaning at the ‘tease’ of his cock just inside my pussy, when he suddenly collapsed his upper body onto me very hard, pinning me in place, ‘walked’ up the bench and then shot his hips forward, ramming me.

He let out an incredibly loud moan of pleasure and I did something I’d only done a few times in life and came so hard, I actually ejaculated, spraying all over his legs and balls. I bucked under him, completely at his mercy now. I tried to move around and realized that I couldn’t, mere seconds before he groaned loudly again and, to my surprise, started forcing his knot into me.

Considering the amount of drool and the huge spray of cum I’d soaked him with, he was able to shove it into my dripping hole after a few thrusts.

God, it vibrated inside me as his cock grew, spurting loads of pre-cum into me, practically every time he shot inside me, I shuddered and came. I knew that dogs will cum the entire time they’re fucking you, but had seen that it was usually only a small amount, once every minute or so, but Spark shot huge wads of hot dog cum at least every 30 seconds or so, I heard my pussy sloshing with all his sperm.

His knot was still expanding inside me, now absolutely huge, plugging me completely. He didn’t use it strictly as a method of cumming, he used it to fuck me and I came over and over again, feeling his hot dog cum spurt into me every few moments. I was surprised, thinking that when the knot was in, they stood still and just filled the bitch with cum.

But, he began taking long, hard thrusts into me, actually stopping at times, I think he was doing what a man would, holding off so he didn’t come too soon but, eventually he began grunting louder and louder, each thrust actually making my legs flail.

Then, he did it, he braced himself and groaned and I felt the contents of those balls that I’d been staring at so long emptying themselves inside me.

I squealed and flopped under him as he continued to thrust, his dog cock vibrating and jerking in me, going off like a fucking fire hose, the tops of my feet bouncing on the floor. He came for 8 minutes inside me, his knot still fully inflated. The temperature of his cum was incredibly hot, I could feel each and every spurt enter me.

I felt his cock starting to shorten inside me and he stood up, that’s when I realized he’d actually ‘collapsed’ his upper body on mine, making sure I couldn’t get away from his pounding cock and stood there, not trying to pull away yet.

Realizing that he couldn’t pull away, dragging me off the ottoman on his knot because of the leash, and still incredibly turned on, I kept bucking beneath him, cumming on his meat while I still could.

As his knot deflated, even with his cock still inside, his cum could finally explode from me and I moaned and bucked, hearing it actually pattering down on the hardwood floor, so much that it sounded like one of us was taking a piss. I felt it flowing down the front of the ottoman, rolling off the leather to create a puddle.

I came a final time, and went to push off, finally satisfied, but, Spark had other plans, that’s when I noticed his breathing had become ragged again. He shoved me down again, his cock stiffening inside me!

I felt him growling and froze, unable to believe he could have any sperm left in that sack of his after the huge load he’d shot. But, he was taking it slow this time and I laid beneath him, trying to get up a few times, loving the way his body would tense up and shove me back down, I realized that even though I was still enjoying it, my pleasure didn’t mean a thing to him, this animal was going to take me until HE was satisfied.

He began hard thrusting again, grunting VERY loudly. If someone had been walking by and the windows had been opened, they would have been able to hear him all the way out to the street. As he rode me, his cock seemed to get even bigger, and I couldn’t help but squeal as his knot re-entered me. When I cried out, I heard him grunt even louder and his cock twitched hard, forcing me into yet another orgasm.

Moaning, I felt him shoving up on the bench further and further, then grunted myself when he climbed on top of me from behind, his back legs now off the floor. His cock penetrated me even deeper and now completely pinned, I squealed under him again, this time, even louder.

He went into a fucking frenzy, his breath gasping, his cock slamming into me, his full 13 inches forced into me. His back legs were sticking out behind us, his weight balanced on his from paws. My body slid up and down on the bench, my entire front eventually being covered in dog cum, as he continued to pump on top of me for another 30 minutes, his cum sloshing inside me again, my cunt sealed shut by his knot.

The second time he began cumming wasn’t as long as the first, but every bit as incredible. I felt his hot spunk exploding from his jerking cock, his moans and gasps of pleasure heard through his chest, my cum covered face turned to the side and body crushed beneath him. My legs flailed on either side of his huge body as he filled me up again.

I shuddered under him too, both of us covered in each other’s cum and when he finally softened enough to pull out, his cum came out with such force, it actually splashed on the floor as I lay on my stomach on the bench, my legs over the side, his cum poured out.

He got off me, his cum still streaming out. I stood up shakily, looking down at my normally flat belly, now actually distended by his cum. Panting, he went and had a long drink, and I stared at his ball sack, dripping with cum.

As soon as I’d cleaned myself up, and re-dressed, he was back to being his previous amicable lump so I took him into the walk in shower and washed him off. Then, did what I’d promised originally, and took him for a good long walk.

The more I thought about having him inside me again, the kinkier my mind became. I decided to go into a pet store to see if there was anything there we could use, such as a collar for me that I could tie to his, loving the idea of being choked while he fucked me.

Then, felt my cunt twitch when I looked at the shock collars. I told them that I had a large dog, who was quite aggressive towards other people. I was told that the shock wouldn’t really hurt him per say but, if it was dialed up to the top setting, it could potentially drop the dog, so I wasn’t supposed to set it that high.

I took it home that night, and after making sure that I had a tea towel between my neck and the collar itself, I hit the remote. My body shook for 30 seconds as I watched myself standing there, naked in the mirror. I took it up slowly and determined that at 3/4 power, it was enough to drop ME to the ground and jitter frantically for those 30 seconds.

I also turned on the anti-barking switch, in case I was to drop the remote while dancing on his dog meat and determined that it didn’t take too much noise to have it shock me when that setting was high too.

The second time I went to pick him up, I was quite nervous, thinking that maybe he’d knock me down in either his apartment or, out on the street, but he acted completely normal until we entered my house again, seeming to realize that this wasn’t something to be done anywhere else.

As soon I unlocked the door, I glanced behind me and saw that the head of his cock was already out of its sheath and gasped looking at it, my pussy was already dripping wet. I heard his hard breathing as I entered the living room.

I stripped out of my clothes and I heard his panting increase as I laid down on the ottoman, legs spread wide. Staring at me, he dove into my lap, frantically licking my throbbing pussy. I reached down and attached the collar around my neck and hit the remote just as his tongue shoved it’s way into my hole.

My body shook hard, my arms and legs thrown wide open, muscles stiff as my hips jerked wildly. He grunted as he tongue fucked me, stiffening it as it swirled around inside me.

Relieved that the shock wouldn’t go through to him, I came hard on his tongue. I looked down at him, his jaw gaping wide, his tongue twisting deep inside me as he stared right back at me, feeling his drool running down my ass crack.

I didn’t have to go up the bench this time to get him to enter me, after around 5 minutes of eating me out, he moaned and came up on his own, straddling me.

On my back this time, and it was so fucking hot to be able to look up at him, his chest rubbing against my tits and he positioned himself over me, hips bucking before he’d even entered me. I reached down and started stroking his dog cock, amazed at how well I could feel it pulsing with each beat of his heart and how hot it was to the touch.

I had to stop jerking him off though, before that knot started to grow, or he’d never be able to get it into me so he could cum. Panting hard and fast, he thrust his tool inside me and, just like the last time, he groaned very loudly… so loud in fact, that it set the collar I was wearing off and I was electrocuted as he forced his dog meat into me. Again, my arms and legs were thrown out and I heard him gasping with pleasure as my pussy milked his huge cock with each pulse of the collar.

This continued again and again and I couldn’t control my screech when he shoved his knot into me, the collar punishing me for my shriek by making me dance under him, hearing him moan so loud as I came repeatedly, the shocks making my pussy spray every time.

The collar made it some of the best sex I’d ever had, every time either one of us made too much noise, I’d be shocked, my pussy clamping shut on his cock and he filled me with his hot cum three times, his knot never getting small enough to get out of me, I felt him stiffen again and again, his hips thrusting wildly.

At one point, during a shock, he took his weight off me to watch me dance and I slid off the soaked ottoman onto the floor. Groaning, he fucked me as my twitching body hung from his cock, my head thrown back, hips jerking in a circle.

After that shock was over, I reached up to take the collar off, realizing this was going to get me really hurt if he kept standing while we were locked together, but he collapsed on top of me, back legs straight out on the floor and his elbows right above my shoulders. I looked up at his face as he fucked me on the floor, my body slipping around in his cum, his eyes were wild as he started fucking me very hard. I grunted helplessly, the collar making me buck under him as he blew his load inside me again.

I heard it splattering on the floor, my heels drumming behind him, his balls contracting and those huge balls jetting load after load of his hot doggy cum deep inside me.

END