Introduction

• Cause: eyelash hairs (adventitious cilia) emerge from the Meibomian ducts (or adjacent margo intermarginalis) to impinge on the cornea.
• Signs: asymptomatic if only fine cilia-like hairs; thicker hairs cause corneal irritation → superficial keratitis Keratitis or corneal ulceration Ulcerative keratitis.
• Diagnosis: history, breed, observation of hairs.
• Treatment: permanent cure requires destruction or removal of the hair root material.
• Prognosis: may need repeated procedures.

Pathogenesis

Etiology

• Inherited in pure breed dogs.
• Can be idiopathic.
• Can occur secondary to inflammatory eyelid margin disease.

Predisposing factors

• The meibomian glands are modified hair follicles and the distichia develops from undifferentiated meibomian tissue.

Pathophysiology

• Hairs/adventitious cilia emerge from in or around the openings of the Meibomian glands  along the eyelid margin. They may be single or multiple.
• Do not always contact the cornea or may just 'float' on the cornea if fine hairs or → corneal irritation if thicker hairs → superficial keratitis Keratitis → corneal ulceration Ulcerative keratitis .

• Distichia can irritate the cornea to result in increased lacrimation, blepharospasm, conjunctivitis and superficial to deep corneal ulceration. A secondary entropion may also occur.

Timecourse

• Juvenile.

Diagnosis

Treatment

Outcomes