Taking a dog in heat for a walk

A little girl asked her mom, "May I take the dog for a walk around the block?"

Mom replied, "No, because Belle is in heat."

"What's that mean?" asked the child.

"Go ask your father, I think he's in the garage."

The little girl went to the garage and asked, "Dad, may I take Belle for a walk around the block? I asked mom, but she said the dog was in heat
and to come to you."

Dad said, "bring Belle over here." He took a rag, soaked it with gasoline, and scrubbed the dog's backside with it and said, "Okay, you can go now, but keep Belle on the leash and only go one time around the block."

The little girl left, and returned a little while later with no dog on the leash.

Surprised, Dad asked, "Where's Belle?"

The little girl said, "She ran out of gas about half-way down the block,
so another dog is pushing her home."