Mark pulled into his driveway right behind his mom's car. "She probably already knows Cal is here, I'm gonna get hell for letting him in while everyone's gone". Mark grabs his backpack from the backseat and makes for the front door. It was bad enough he had to go to communinty college while his old high school friends were living large at a party school, why did Cal have to screw with him. As Mark turns the door handle he remembers that it's because he had a crush on Cal's sister Katy, but during his senior year she had turned into a real bitch.
Mark opens the door to see a squatting black lab in a dimly lit hallway. "Damn it Cal!, why'd you bring your stupid dog over!", now you know your mom's really gonna be pissed. You smell canine odors left over from Cal and Darleen's mounting though you don't recognize them. You go to open the closet door looking for the steam vac when the labrador tackles you head on. She slobbers all over your face and seems to be gripping you around your waist with her thighs.
"Down Buster!", your shoulders are pinned by the dog's forepaws but you can still manuever your hands. You try to punch the dog in the balls but soon discover that this dog is female, and very determined to get her tongue in your mouth.
Her deathgrip on your crotch and wagging tail thumping against the inside of your legs quickly causes an erection down your pants. You feel the heat and moisture eminating from beneath her tail and relax, letting her mouth explore yours. After enjoying the sensation for about a minute you decide to roll over and end this, but to you surprise you look up to see a noticably male german shepherd take an interest in your groin.
The male nozzles his way down the bitch's crotch and grabs your zipper. He starts pulling and tearing, all the while thrashing his head like playing tug of war, the lab bitch doing a remarkable job of holding you in place. Before you can act the german shepherd jerks backward, its muzzle proudly flailing the entire front assembly of your pants and your underwear. You don't want to have sex with a dog, but with nothing holding your penis down it now sticks up, your head feeling the wagging at the base of her tail.
The bitch shifts her grip and quickly impales her vagina onto your cock. She thrusts herself up and down on you, the heat and pleasure are wild, and you rythmetically thrust back into her. Her forepaws are no longer on you, but the watchful eyes of a salivating german shepherd tell you not to try hurting this bitch. The grip of her doggy thighs is soon loosened in her new position and you take a try at pulling out.
The bitch lets out a yelp and is pulled back with you, your own cack having dragged her along. The german shepherd goes back to playing with his new rag toy and you try again to get the dog off you. You roll over so the bitch is now beneath you, her panting showing no indication of displeasure. Your cock however is uncomfortably twisted and you move the dog so she's beneath you doggy style. Moving both your hands to her rump you feel her coarse black fur, you push against her butt making her howl while the base of your penis feels an aching pain. You decide to pull yourself out, but discover that not only is your cock embedded all the way up the bitch's cunt, but the same coarse hair covers your thighs and butt as well.
You feel somthing growing from the base of your spine into the open air and you pant heavily. You begin again to thrust against the bitch in a weak attempt to release yourself, but this time you also make sure to enjoy it. You feel your body slowly rearranging into that of a male labrador retriever from your groin outward. The change reaches your knees making it easier for both of you to stand, inert mammery glands form up your front and you notice your neck getting longer. You suddenly spasm releasing multiple loads into your partner, your mind returns to you and you notice...