Introduction

• An outward turning of the eyelid margin, sagging of lower lid is most common form; palpebral conjunctiva is exposed.
• Cause: congenital in some breeds.
• Acquired often due to surgical overcorrection of entropion, senile entropion.
• Signs: ectropion → exposure conjunctivitis Conjunctivitis or keratitis Keratitis.
• Diagnosis: clinical examination.
• Treatment: if needed is surgical.
• Prognosis: good.

Pathogenesis

Etiology

• Familial: inheritance not determined.

• Citatricial: previous scarring of the eyelid (including previous entropion treatment Entropion ).
• Atonic: decreased elasticity in the skin on the top of the head → slipping down of the palpebral fissures → lower lid ectropion.
• Paralytic: damage to the facial nerve (cranial nerve VII) which supplies muscularis orbicularis oculi and muscularis levator palpebrae superioris. Seen in combination with ptosis and facial anesthesia. Middle ear disease may be responsible.

Predisposing factors

• Disease in most dogs is secondary to breed-associated alterations in facial conformation and eyelid support. Laxity of the palpebral tissue and deficiency of the lateral retractor muscle cause ectropion. Excessive length of palpebral tissue, small globe size, relative enophthalmos, weakness of the lateral retractor muscle, and heavy facial skin folds and pendulous pinnae cause ventral ectropion.

Pathophysiology

• Familial: inheritance pattern not defined. Palpebral fissure too long and lax.
• Diamond Eye: in St Bernard and Bloodhound. Notch in center of lids results in both ectropion (adjacent to notch) and entropion (adjacent to medial and lateral canthi). Entropion usually worse on upper lid, ectropion on lower lid. Difficult to surgically repair.
• Physiological: after a hard working day - does not require treatment. Seen in the working Retriever and Setter.

• Cicatricial: including overcorrection of an entropion.
• Atonic: especially English Cocker Spaniel English Cocker Spaniel. A loss of elasticity in the skin on the top of the head, combined with heavy ears → slipping of the palpebral fissures → upper lid entropion Entropion and lower lid ectropion .
• Paralytic: damage to facial nerve (cranial nerve VII) causes loss of orbicularis muscle tone.
• Neurologic: loss of orbital or periorbital mass in masticatory muscle myositis may result in ectropion.
• Hypothyroidism: can cause ectropion bilaterally.

Timecourse

• Time to exposure keratitis/conjunctivitis dependent on severity of ectropion.
• Ectropion noted in predisposed breeds by 1 year of age.

Diagnosis

Treatment

Prevention

Outcomes