A dog and a cat exhibiting the fight-or-flight response.
<a rel="nofollow" class="external text" href="https://www.flickr.com/people/68877611@N00">Peretz Partensky</a> from San Francisco, USA
CC BY-SA 2.0
<a rel="nofollow" class="external text" href="https://www.flickr.com/photos/ifl/3926001309/">This was a timely capture</a>