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: In the chronic treatment , beagle dogs of each sex were given intravenously once every 3 weeks , either a sublethal dose of doxorubicin ( 1 . 5 mg / kg ) or SM - 5887 ( 2 . 5 mg / kg ) .
### Output Text:
In the chronic treatment , beagle dogs of each sex were given intravenously once every 3 weeks , either a sublethal dose of <span class="chemical">doxorubicin</span> ( 1 . 5 mg / kg ) or <span class="chemical">SM - 5887</span> ( 2 . 5 mg / kg ) . 