| Tiffany entered her house panting. ?Her after school runs always left her somewhat drained and much in need of a shower. ?She went up to her room to undress and greeted her brother's large German shepherd who was sitting in the hallway.? ? ? ?"Hi Max." she said. ?"You get left alone again today?"? ? ? ?Tiffany had found a note downstairs from her mother telling her that her parents would be out all evening. ?As she started undressing, she noticed that Max had followed her in. ?Max had been staying in her room since her brother went away to college, and Tiffany was used to undressing in front of him.? ? ? ?As she was sitting on her bed completely naked, Tiffany decided that this would be a good time to work off some of that extra sexual energy that had been building all day long. ?Her mother was usually home all day, so she was used to relieving herself only at night while in bed, but this time she did so while sitting on the bed. ?? ? ? ?Her fingers started probing her inner depth. ?She then removed her moist finger and started massaging her emerging clitoris. ?Tiffany moaned as she ground the palm of her hand over her privates. ?Her hips started thrashing as she lay back on the bed and started really getting into it. ?She felt a brief pang of embarrassment as she noticed Max was sitting in the corner watching intently. ?Her attention was quickly brought back to her impending orgasm as she was using one hand to rub the area around her very sensitive clit and the other to alternately pinch her nipples and insert a finger into virgin body. ?Her pace picked up as she reached the point of no return, and she found herself being stretched by two of her own fingers. All this time Max was watching with increasing curiosity. The smell in the air was starting to arouse him, and he wasn't sure where it was coming from. As he was watching Tiffany writhe around on the bed, he started to realize that she was the source of his excitement. His large German shepherd penis slowly started to emerge from his sheath as he sat watching her. Tiffany could not believe her level of excitement or the magnitude of her orgasm. She moaned loudly as she stretched her virgin lips wider then she ever had before. She had put a third finger in in the throes of her sexual fury which pushed her over the edge towards her orgasm. As it his her full force, she fell from the bed, semi-conscious. "Wow!" she said to herself. "That was incredible. Good thing I did this before my shower, I'm a sticky mess." As she got onto her hands and knees to pick herself up, she felt Max sniffing her behind. "No! Get away, Max!", she cried as his cold nose bumped her glowing womanhood. She pushed him away, but as soon as she turned back to get up, his tongue lashed out for a direct his on her clit. "Gaaa...!" she said as this took her legs out from under her. She sat in disbelief of how wonderful it felt. As Max's tongue worked its way into her, she realized what was happening and pushed him away again while she reached over the bed for her towel. "What the...? No, Max, get off!", Tiffany yelled as she felt his body press hers into the mattress of the bed. He had seen her kneeling on the floor and decided to take some action. It took a moment for Tiffany to realize what he was doing, but she was unable to move to get avay from him as he pinned her from above. His 90 pound body was too much for her to lift even as she realized that his cock was poking around her nether regions as he tried to penetrate her. "Max! NO! Bad dog!", she screamed at him in an effort to get him to stop, but he was too intent on the female in heat beneath him. She went rigid as his doggy cock found its way to her dripping hole. It was still wet from when she had fingered herself, and that made it much easier for Max. Tiffany whimpered as the first trust of his larger than human prick broke through her maidenhood. His second thrust went in farther as she was stretched as she never had been before. As she lay helpless, pinned beneath the dog, she felt him going faster and deeper with each trust. Tiffany could feel his drool dripping onto her back as he worked himself into a fevered pitch violating the young and helpless girl with the bestial act. The stimulation was incredible, and Tiffany found her body responding to the dog, against her will. "Oh....shit, Max." she said. Max was pounding her newly deflowered body faster that she thought possible, and she was also getting really excited despite her revulsion of what the animal was doing to her. She moved her hands behind herself and felt Max's dick as it pounded in and out. She couldn't believe that something that immense was actually going into her little body. She was even more surprised to find that the only thing preventing it from going deeper was the knot at the base of his penis. Getting turned on, she tried to open her legs more and stretch her lips apart to see is she could get the base of his cock in as well.Each thrust pushed the knot in a little further, pushing her closer to the edge of a major orgasm. Max must have liked the extra stimulation as well, because he started making mini-growls with each massive thrust. Even as she was entering the orgasm, she knew that the knot was too large and would not go all the way in. As the full force of the orgasm hit her, she pushed back one last time, trying to get his dick in as deep as she could. Unfortunately, it was at the same time as Max started cumming. He also pushed in, hard. Tiffany nearly screamed as his knot was forced all the way in. This just made Max push harder with the added tightness around his prick. Max used this extra stimulation to pump a very full load of doggy come into his bitch. He pushed his dick and knot as far as he could as he came with a strange growl. Tiffany could feel the spurts of hot cum as they hit her innermost parts. Tiffany, couldn't move away from the painful penetration, but she did realize that it was over, and tried to get him off. He would have none of that as his bestial urge to impregnate her made him continue pushing to keep his knot within her. She suddenly realized that the knot, which was very large to begin with, was growing much larger, pushing his dick deeper. She recalled that this was how the male dog "tied" to the female after mating so that the sperm would not leak out. This stimulation gave her one more orgasmic jolt before she realized that not only was she trapped beneath him, but he was becoming trapped within her. She tried to get him to back off, but the growing knot was pulling itself deeper into her cunt as the inside of her vaginal cavity was larger than the opening. She knew that the knot just barely fit into her in the first place, and that was forced in painfully, so he was probably stuck until it went back down to that size again. However, the knot was becoming so large that it was very painful, even thought it was on the inside of her vaginal cavity. Not only did the knot feel to be about the size of a tennis ball, which she could never have fit through her opening, but it was also pushing his cock against her womb with far too much pressure. Max decided that this was enough, and tried to get off. He managed to get his body off of hers, but could not move away as he was locked firmly inside of her. When Max got off, she felt his cock trying to pull out which increased the pain. As Tiffany lay there whimpering in pain, she realized that she looked and sounded much like the female dogs that she had seen Max fuck. She tried to get up to see if she could do something about him, but the tugging on Max's penis made the knot get even bigger, and she lay back down in pain. As she waited for him to shrink enough to get out, she realized that despite the pain, this had been the most sexually exiting time she had ever had. Max had not acted maliciously, but out of animal instinct. She decided that she could not tell anyone about this, or even punish Max herself. She might even allow him to "force" her another time, but without the "tie". As she sat there waiting, wondering why she could not feel him getting any smaller, she recalled with a sinking sensation that the times she saw Max tied to a female dog, he usually stayed that way for half an hour.