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: BACKGROUND : In dogs , a large amount of intravenous cocaine causes a profound deterioration of left ventricular ( LV ) systolic function and an increase in LV end - diastolic pressure .
### Output Text:
BACKGROUND : In dogs , a large amount of intravenous <span class="chemical">cocaine</span> causes a profound deterioration of left ventricular ( LV ) systolic function and an increase in LV end - diastolic pressure . 