Chapter 1
13 year-old Izzy sat in her room, fingering herself while her parents were out. Duke, her German Shepard, watched curiously as she moaned softly. His penis was poking out of its sheath, but Izzy didn't see, she was to pre-occupied. As he walked up, Izzy squirted, and Duke rushed forward, eager to see what it tasted like. He lapped up what he could from her bed, and moved on to her pussy, much to Izzy's surprise. She pushed his head away with a small slap. He moved in from a different angle, seeing if he could find success. 
"Bad dog!" She said, annoyed by his constant attempts. 
Duke was persistent, and though Izzy knew it was not normal, she was curious to see what he would do. She let him lick her pussy, and soon he found the source of all the juices running out of the teens pussy. The young girl gasped, amazed at how the dog's tongue reached into places she never knew existed before now. Izzy has now humping Duke's tongue
"Mm, good boy, keep doing that!" She shouted, her young pussy squirting juices all over Duke's face.
Duke did what she said, though it's not like he wouldn't, he was enjoying himself as much as Izzy was enjoying him. Finally, after minutes of being licked by her huge dog, she pushed him away, knowing her parents would be home soon. She quickly made her bed, covering the huge wet mark the best she could. Duke kept jumping up on her, occasionally even knocking her down, but never succeeded in penetrating the virgin pussy. Izzy would just push him off, and continue what she was doing before. She took a brief shower, re-dressed and put Duke out to use the bathroom. She heard the front door open.

Chapter 2
Izzy had just gotten home from school, and her parents were still at work, so she figured she had a little time to see Duke. She let him out, then brought him upstairs. She had a bottle of lube that one of the girls at school slipped her and a few towels, all she needed, she thought. She had read a few things on the internet about how to give a dog a boner. She also read up on letting your dog fuck you. She sat down right next to Duke and slipped her hand to his belly, searching for his sheath. Once she found it, she rubbed it gently, seeing how Duke would react. He paid no attention, but his red package peeked out. Izzy waited until it was halfway out, then stuck her head under and began sucking his cock. It tasted a bit salty, but she didn’t mind, and soon his whole cock was out of his sheath, all 8” of it. She slipped it out of her mouth, but at this point it wasn’t easy, as Duke was basically humping her head. She saw a little bit of pre-cum dripping out, and she knew she didn’t have long. She kept stroking the dog’s huge cock, and she felt a warm liquid cover her hand.
“Dammit!” She said in frustration.
She stuck her head under the dog again, and resumed sucking his cock, which was now spilling out cum. It filled her mouth, tasting salty and sticky. It was a good 15 minutes before the dog stopped, and Izzy had swallowed every last drop of cum.

Chapter 3
This was it. She was going full on, even though she failed the day before, she learned from her mistakes and realized when to stick it in. She grabbed the unused bottle of lube from it's hiding spot, and grabbed Duke. She Sat on the ground and stroked Duke's sheath. Once his cock was visible, she rubbed some lube on her pussy, and a little bit on Duke's huge cock. She slipped socks onto his feet and got on her hands and knees. Duke sniffed around her pussy, licking it as she moaned. Suddenly he mounted her, and Izzy nearly collapsed. She felt his cock poking around her ass, and she had the realization that he might go into her ass, and if he did, it would hurt... A lot. She stuck a hand behind her, and guided his cock in. She gasped as her lips opened for the huge member. She felt goose bumps on her arms and Duke slammed his cock into her, breaking her hymen, making her grimace. She didn't care though, Duke was pleasing her too much. Duke's huge knot formed in her, and it felt like someone started fisting her. She grimaced again as Duke's knot kept pulling against her vaginal walls. It felt like it was ripping her insides. She got the lube and poured half the bottle into her hand. She rubbed it into her pussy, hoping it may relieve some of the pain. She felt Duke's cum leaking through her insides. The mixture of blood and semen leaked through her pussy lips. She felt Duke trying to pull out of her. Attempt after painful attempt, he failed and failed, kept in by the teen's tight pussy. Her soft cunt was being ripped apart by Duke's huge cock, and finally, he pulled his knot out, making Izzy scream out. Suddenly, cum and blood spilled out of her pussy, covering the carpets. Duke inspected his handiwork, and went to the corner to clean himself up. Izzy lay motionless on the floor, and she squirted, nearly halfway across her room. She heard the door slam.

To be continued