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: No changes in haloperidol - induced catalepsy or MK - 801 - induced locomotion were seen following PD .
### Output Text:
No changes in <span class="chemical">haloperidol</span> - induced catalepsy or <span class="chemical">MK - 801</span> - induced locomotion were seen following PD . 