• 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 or corneal ulceration
• Diagnosis: history, observation of hairs.
• Treatment: plucking is a short-term solution; permanent cure requires destruction or removal of the hair root material.
• Prognosis: may need repeated procedures.

• Worldwide.

• Most clinical signs noticed in young animals.

• Cost of treatment.

• Often idiopathic.
• May occur secondary to inflammatory eyelid margin disease.
• May be inherited.

General

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

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

Refereed papers

• Recent references from PubMed and VetMedResource.
• Arteaga K & Crasta M (2021) Successful treatment of distichiasis in a cow using a direct-contact 810-nm diode laser. Vet Surg 50 (5), 1164-1168 PubMed.

Other sources of information

• UCDavis Veterinary Medicine (online) Distichiasis DNA Test. Veterinary Genetics Laboratory, USA. Website: www.vgl.ucdavis.edu.