"I think Buster needs to go out," Sarah said as she faked just waking up. Buster licked her face in appreciation for what she had just done.
"Alright. I could use a little break myself," Clara said pulling the car over by a wooded area.
"I'll take him into the woods a little ways and let him do whatever," Katy said.
"No...I want to take him," Sarah said as she grabbed his collar.
"Alright but don't go far."
"OK," Sarah replied smiling. She knew what she was going to do with Buster.
Katy and Clara waited by the car. They had not had time to get reacquainted. Their hands touched briefly. Katy became so overcome with desire that she reached over and grabbed Clara's tit. Clara grabbed Katy's hand and pulled Katy toward her. They started kissing and feeling each other. Katy slid her hand down Clara's back and reached in her pants. She snaked her fingers down to Clara's slit and started fingering her. Clara did the same to Katy. They became lost in each other.
Sarah turned around and saw her sister making out with Clara and became further aroused. She pulled Buster behind some trees and began to strip. When she was done, she grabbed his head and forced his nose into her crotch. It was cold at first but warmed up once he started licking. She orgasmed once and then dropped to the ground. She got on her hands and knees and presented herself to him.
Buster walked around her a few times before finally licking her ass once and then mounting her. He continued to slam his cock into her until his knot was locked in. He pumped in and out of her hard and fast like a machine.
Sarah started feeling warm and felt a tingling in her hands. She looked down to see them changing into paws. Fur sprouted out of them and traveled up her arms. This fueled her passion further. She wanted to be a dog. She could feel her feet and legs changing just as her hands had. Her tail shot out and wagged a little. Fur covered the rest of her body before shooting up her neck. She could see her face pushing out into a muzzle.
As Buster finished, the transformation completed giving Sarah the greatest orgasm that she had ever experienced.
Back at the car, Katy and Clara finally had broken their embrace. They were still waiting for Sarah to come back. It had been nearly 20 minutes.
"Sarah, are you OK?" Katy shouted at the woods. There was no answer. "Sarah? Buster?" she tried again.
Buster appear at the edge of the tree line with another dog and ran to the car. He was followed by a German Shepard.
The German Shepard got close enough to the car for Katy to see that it was a female and then she drew her own conclusion. "Sarah?"
The dog barked happily and came over to lick Katy's hand. Katy knew it was her sister and what must have happened.
Clara giggled a little. "You two must just share the same instincts."