Has anyone heard of someone using a dog whistle to antagonize a dog?

[Baitball Blogger]

My dog has been barking all evening, and with one exception, there was no one there. The last time I let her out of the house she nearly flipped over she was so spooked.

[Oneironaut]

1. Could be anything, really.

I used to have a sensitive barker. Anything, from the UPS truck to a leaf crinkling by would agitate him.

[ohnoyoudidnt]

2. I have heard of it happening.

Like people doing it to their neighbors dogs to be pricks. But as oneironaut said, it could be something else. Maybe there is a critter somewhere about your house that your dog is sensing and you don't see.

[milestogo]

3. Are there coyotes or other wildlife near your home?

[Baitball Blogger]

4. No.

She seems to be reacting to a sound.