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: ANIMALS : 12 cats suspected to have idiopathic epilepsy that was poorly controlled with phenobarbital or that had unacceptable adverse effects when treated with phenobarbital .
### Output Text:
ANIMALS : 12 cats suspected to have idiopathic epilepsy that was poorly controlled with <span class="chemical">phenobarbital</span> or that had unacceptable adverse effects when treated with <span class="chemical">phenobarbital</span> . 