Canine Eyelid Disease—Entropion

Entropion, the inward turning of the eyelid margin, is a prevalent canine ophthalmic condition impacting breeds predisposed to facial skin laxity. This condition causes the eyelashes and hairs to persistently irritate the conjunctiva and cornea, leading to significant discomfort and potential long-term damage. This article delves into the causes, symptoms, and treatment options for canine entropion.

I. Etiology of Canine Entropion

The underlying causes of entropion are multifaceted and can be broadly categorized as developmental, spasmodic, or acquired.

A. Developmental Entropion: This form is often breed-specific and hereditary, linked to inherent structural defects in the facial and ocular anatomy. Breeds such as Shar-Peis, Chow Chows, Bulldogs, and several smaller breeds are particularly susceptible. The severity varies; Shar-Peis may exhibit complete eyelid inversion, while smaller breeds may only experience medial lower eyelid entropion. The precise genetic mechanisms remain unclear, though a simple dominant inheritance pattern is suspected, with the exact mode of transmission difficult to pinpoint. The depth and size of the orbit can also play a role, as seen in Great Danes where a large, deep orbit may lack sufficient support for the eyelid, predisposing them to entropion.

B. Spasmodic Entropion: This type arises secondary to irritation or inflammation of the eye. Conditions such as conjunctivitis (both dry and infectious), corneal ulcers, foreign bodies, distichiasis (abnormal eyelash growth), and trichiasis (misdirected eyelashes) can trigger spasms in the orbicularis oculi muscle, resulting in temporary eyelid inversion. This often affects only one eye and can occur at any age. Ocular trauma or inflammation leading to fibrotic changes in the eyelid can also contribute to this form of entropion. The alleviation of the primary condition often leads to a resolution of the entropion.

C. Acquired Entropion: This typically manifests later in life, often associated with age-related changes or previous eye injuries. Loss of orbital fat, muscle atrophy (especially of the malar muscle), and decreased skin elasticity due to aging all contribute to the weakening of eyelid support structures, leading to inward rolling.

II. Clinical Presentation of Canine Entropion

The clinical signs of entropion range from mild to severe. Mild cases may present with only subtle irritation, mild tearing, and intermittent discomfort as eyelashes or hairs lightly brush against the ocular surface. However, severe entropion can cause significant problems. The eyelids may be difficult to open, resulting in pain, photophobia (light sensitivity), blepharospasm (involuntary eyelid closure), and excessive tearing. Chronic irritation leads to secondary complications, including severe conjunctivitis and keratitis (inflammation of the cornea), potentially resulting in corneal ulceration, scarring, and even vision loss. The diagnosis is typically made through a thorough ophthalmic examination, observing the eyelid’s position and assessing the presence of corneal or conjunctival irritation.

III. Treatment Modalities for Canine Entropion

Treatment strategies for entropion vary depending on the cause and severity.

A. Surgical Correction: This is the most common treatment for developmental and persistent spasmodic or acquired entropion. Surgery aims to reposition the eyelid margin, preventing the eyelashes from rubbing against the eye. The specific surgical technique employed depends on the breed, the severity of the entropion, and the surgeon’s preference. Several techniques exist, including wedge resection, lateral canthoplasty (tightening the outer corner of the eye), and full-thickness eyelid resection. For puppies with severe developmental entropion, temporary eyelid sutures may be placed at a young age (e.g., 3 weeks in Shar-Peis) to protect the cornea from damage until a definitive surgical correction can be performed at a later age (usually 4-6 months or when facial features are fully developed).

B. Medical Management: For mild, temporary cases of spasmodic entropion caused by an underlying condition like conjunctivitis, addressing the primary condition is crucial. Medical management may include topical antibiotics, anti-inflammatory medications, or artificial tears to alleviate irritation. Temporary tarsorrhaphy (suturing the eyelids partially closed) can offer protection during the treatment of the underlying disease. Soft contact lenses can sometimes provide temporary relief by physically separating the eyelashes from the eye.

C. Post-operative Care: Post-surgical care is vital to ensure successful healing and prevent complications. This typically involves the use of an Elizabethan collar to prevent the pet from scratching or rubbing the eyes, the administration of topical antibiotic and/or anti-inflammatory eye drops or ointments, and regular monitoring by a veterinarian.

IV. Prognosis

With timely and appropriate intervention, the prognosis for canine entropion is generally good. Surgical correction is usually successful in resolving the eyelid malposition and preventing long-term complications. However, the success of treatment depends heavily on accurate diagnosis, proper surgical technique, and diligent post-operative care. Regular veterinary check-ups are essential to monitor for recurrence or complications. Ignoring entropion can lead to permanent corneal damage and vision impairment, underscoring the importance of early intervention.