In the sentence extracted from biomedical literature, identify all the chemical entities. The required answer format is the same sentence with HTML <span> tags to mark up specific entities. 
### Entity Markup Guides:
Use <span class="chemical"> to denote a chemical.

### Input Text: The four dogs without a perfusion defect had a stenosis that resulted in a mild ( 0 % to 50 % ) reduction in dipyridamole - induced hyperemia .
### Output Text:
The four dogs without a perfusion defect had a stenosis that resulted in a mild ( 0 % to 50 % ) reduction in <span class="chemical">dipyridamole</span> - induced hyperemia . 