Katy had successfully used the dildo to masturbate with although small she had never felt the power of the penis before. With lust she started to look at her adopted sister. After several days had passed she was making tomato soup for her now 19 yo sister who was having a gap year before going to Maple Leaf college. Inside the soup was a pre-med, designed to make Sarah drowsy and dopey but not knocked out.
Leading a weak Sarah up to the loft she had the collar around her neck. Her body started to change into a Mountain Dog and Katy, nude, stuck the base of the dildo against her vagina. Soon a German Shepard cock was in place, the timing had to be perfect. Just as her sister had collapsed on all fours Katy pounced. The curse was slowed by the drugs in Sarah's blood and her natural resistance.
Doubled over she was like a blind rabbit in the headlights. Katy ripped her sister's panties off with her claw like hands, using her padded fingers to grope for Sarah's hole. Sarah tried to fight the curse, the drugs and Katy. She bucked and kicked but the curse powered through Katy as she seized her sister by her huge breasts angling her doggie cock.
"No...nooo..." wailed Sarah.
With a howl like a wolf Katy was inside her sister her claws raking across Sarah's breasts and back her ears were those of a German Shepard, her legs had become the hindquarters of a dog as a glorious furry tail feet long. As she was turning more into a dog Katy exploded shooting her seed into her sister's inner thigh. Katy pulled the dildo off and rapidly turned back into a 20 something old woman.
She left Sarah as a Mountain Dog for a few hours chained to the wall bracket. Why had Katy done this to her sister? Because she was pregnant with puppies, Cal being the father.