Surface diseases that involve the conjunctiva of the eyelids or globe or affect the cornea are the most commonly treated ocular diseases in small animal practice. When it is not possible to establish a definitive diagnosis through clinical presentation alone, cytologic and histopathologic evaluations are useful diagnostic tools. Often overlooked, these evaluations can pinpoint a diagnosis or at least rule out many diseases on the differential list. In addition, accurate and appropriate diagnoses from cytologic and histopathologic ocular tissue samples are often more reliable than culture results, especially for viral diseases. These tests may be underused due to lack of education regarding what information they can provide, lack of training in how to perform the procedures, or a misconception that general anesthesia or sedation is always necessary. Although chemical restraint may occasionally be required, most patients tolerate conjunctival procedures with only topical anesthesia.