It shouldn't matter whether the headers are images or text. You'd simply replace the text inside each header to an image tag, for example:
Code:
<h3 class="mypets"><img src="expand.jpg" /></h3>
<div class="thepet">
<img src="http://i10.tinypic.com/7xlrga1.jpg" />
The dog is a domestic subspecies of the wolf, a mammal of the Canidae family of the order Carnivora. The term encompasses both feral and pet varieties and is also sometimes used to describe wild canids of other subspecies or species. The domestic dog has been (and continues to be) one of the most widely-kept working and companion animals in human history, as well as being a food source in some cultures.
</div>
You may also want to change the H3 tag to DIV instead.
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