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: PROCEDURES : Cats were treated with levetiracetam ( 20 mg / kg [ 9 . 1 mg / lb ] , PO , q 8 h ) .
### Output Text:
PROCEDURES : Cats were treated with <span class="chemical">levetiracetam</span> ( 20 mg / kg [ 9 . 1 mg / lb ] , PO , q 8 h ) . 