Feline focus: Update on feline upper respiratory diseases: introduction and diagnostics.

Clinical signs of upper respiratory disease are common in cats. Common diagnostic differentials include viral, bacterial, and fungal infections; chronic rhinosinusitis; foreign bodies; tooth root disease; neoplasia; inflammatory polyps; nasopharyngeal stenosis; and trauma. A complete diagnostic workup is important to determine the etiology so that the treatment regimen can be appropriately directed and maximal response to therapy obtained.