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: This study was designed to investigate the chronic cardiotoxic potential of SM - 5887 and a possible deteriorating effect of SM - 5887 on low - grade cardiotoxicity pre - induced by doxorubicin in beagle dogs .
### Output Text:
This study was designed to investigate the chronic cardiotoxic potential of <span class="chemical">SM - 5887</span> and a possible deteriorating effect of <span class="chemical">SM - 5887</span> on low - grade cardiotoxicity pre - induced by <span class="chemical">doxorubicin</span> in beagle dogs . 