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Ectropion in Dogs

Ectropion is a condition which describes the margin of the eyelid rolling outward, resulting in exposure of the palpebral conjunctiva (the portion of tissue that lines the inner lids). Exposure and poor tear distribution may predispose the patient to sight-threatening corneal disease. It occurs mostly in dogs; seldom in cats. Breeds with higher than average prevalence include sporting breeds (e.g., Spaniels, hounds, and retrievers); giant breeds (e.g., St. Bernards and mastiffs); and any breed with loose facial skin (especially bloodhounds). There is a genetic predisposition in listed breeds, and it may occur in dogs less than one year old. When it is acquired or noted in other breeds, it often occurs late in life, and is secondary to age-related loss of facial musculature skin tension. It is intermittent, and is often caused by fatigue. It may be observed after strenuous exercise or with drowsiness.

Symptoms and Types

• Protrusion of the lower eyelid, with lack of contact of the lower lid to the eye globe, and exposure of the palpebral conjunctiva and the third eyelid – can usually be plainly seen
• Facial staining caused by poor tear drainage - tears spill over onto the face instead of passing from the eye to the nose via the tear ducts
• History of discharge owing to conjunctival exposure (the clear moist membrane that covers the inner surfaces of the eyelids and the front of eyeball)
• Recurrent foreign object irritation
• History of bacterial conjunctivitis (inflammation of the conjunctiva)

Causes

• Usually secondary to breed-associated alterations in facial conformation and eyelid support
• Marked weight loss or muscle mass loss about the head and eye orbits may result in the disease being acquired
• Tragic facial expression in hypothyroid dogs
• Scarring of the eyelids secondary to injury, or after overcorrection of entropion - a medical condition in which the eyelids fold inward. Scarring may result in cicatricial disease, a diverse group of rare disorders based on new tissue growth over a wound, which destroys the hair follicle by replacing it with scar tissue, resulting in permanent hair loss

Diagnosis

As part of the normal examination a blood test will be conducted to look for bacteria that might be causing the symptoms, and a thorough eye exam will be conducted to look for corneal ulcerations. A fluorescein stain, a non-invasive dye that shows details of the eye under blue light, will be used to examine the eye for abrasions or foreign objects. If your dog falls into the list of breeds that is predisposed to this condition, your veterinarian will take that into account. In non-predisposed breeds, and patients with late-age onset, an underlying disorder will be considered as a causative factor. In patients with inflammation of the muscles that affect chewing, loss of mass in the eye may cause the condition. Nerve paralysis in the eye, a condition associated with lack of muscle tone of the eye muscles, will also be considered.