[A] Abnormalities in eyelid structure or conformation may be congenital or acquired
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Canine Eyelid Neoplasms

Abnormalities in eyelid structure or conformation may be congenital or acquired.

Written exclusively for Eurobichons / Versailles Kennels by:

David T. Ramsey, DVM, Diplomate ACVO
Associate Professor, Comparative Ophthalmology,
Department of Small Animal Clinical Sciences
D-208 Veterinary Medical Center
Michigan State University
East Lansing, MI 48824-1314

Congenital

1.Eyelid Agenesis (coloboma). Eyelid agenesis is a congenital defect of that occurs most frequently in cats. The upper temporal eyelid (lateral 1/3 to 2/3) fails to develop resulting in a full- or partial-thickness defect (Figure 1). Absence of eyelids results in secondary trichiasis and exposure keratoconjunctivitis. If the agenesis is mild, cryoepilation or entropion surgery can be performed to limit trichiasis. If severe, surgical correction requires use of grafting procedures, using the lower eyelid and the conjunctiva of the nictitating membrane as the donor site, to construct a functional eyelid.

2. Ankyloblepharon. Ankyloblepharon is adhesion of the eyelid margins to each other. Dogs and cats have physiologic ankyloblepharon until 10-14 days of age. If it persists past 15 days of age, infection of the conjunctival sac (ophthalmia neonatorum) may occur and is typified clinically by excessive swelling and/or discharge at the medial canthus (Figure 2). The eyelids should be separated using gentle (digital) traction. I recommend massaging the fused lids toward the medial canthus with a warm, wet cotton ball to effect separation. Exudate should be submitted for bacterial culture. The palpebral fissure should be flushed with sterile saline and a broad-spectrum antibiotic ointment applied topically q 6 h. Untreated neonatal conjunctivitis can lead to severe corneal scarring or loss of the globe.

3. Micropalpebral fissures. Narrowing of the palpebral fissures is usually associated with other concurrent congenital defects (entropion, microphthalmos) in the Shar Pei, Chow chow, Kerry blue terrier and Collie. Correction usually requires blepharoplastic surgical procedure in which conjunctiva is sutured to the incised eyelid surfaces to enlarge the fissure.

4. Macropalpebral fissures. Excessively large palpebral fissures is common in brachycephalic dog breeds with congenital exophthalmos (shallow orbits), the Bloodhound, St. Bernard, American and English Cocker spaniel and the bichons breeds. The dorsal sclera may be exposed and prominence of the globe may prevent closure of the eyelids while sleeping (nocturnal lagophthalmos). Secondary exposure keratitis may result in corneal pigmentation and fibrosis. Surgical shortening the palpebral fissure is indicated but must be performed where the abnormality exists (permanent lateral or medial canthoplasty).

5. Dermoid. A dermoid is a choristoma (normal tissue in an abnormal location). Dermoids may be present on the eyelid (Figure 3) but most frequently they are located on the lateral conjunctiva or cornea. Treatment requires surgical excision and is curative.

Acquired

1. Entropion. Entropion is defined as inversion of the eyelid margin. Secondary trichiasis (misdirected hairs of the eyelids) often results. The lower lateral eyelid is usually involved but depending on the breed, any part of the eyelid margin can be involved. Clinical signs vary from epiphora to corneal perforation. Entropion is classified as primary (anatomical), spastic (physiological), and cicatricial (scarring).

a. Primary (anatomical). Primary entropion results from a structural abnormality of the eyelid/tarsal plate. Primary entropion is differentiated from secondary entropion by response to topical anesthetic: If entropion persists after instillation or topical anesthetic, there is no spastic component. When entropion occurs in a puppy or foal (e.g., prior to mature facial conformation), temporary “tacking sutures can be placed to result in eversion of the eyelid margins. Several vertical mattress sutures are placed at the haired-nonhaired junction (approximately 3-mm from the eyelid margin) at partial-thickness depth in the lid and apposed to the skin overlying the bony orbital margin.2 Placement of tacking sutures often eliminates the need for surgical correction of entropion later in life. Tissue adhesives and staples have also been used to tack eyelids. Once mature facial conformation is attained, surgical correction requires use of a blepharoplastic surgical technique. The shape, size, and location of the surgical incision vary with the breed, age, severity, and location of entropion. Silk sutures have been recommended to oppose the wound. Medial canthus entropion is a common cause of epiphora in brachycephalic canine and feline breeds, and also occurs in canine breeds with tense eyelid-to-globe conformations (Toy and Miniature Poodles, Bichon Frise, Maltese, others). The lesion may be subtle and is often overlooked as a cause of epiphora. Many of these breeds have concurrent medial canthal entropion and excessive nasal folds. Medial canthoplasty surgery is required. Care should be exercised to avoid accidentally incising the canaliculi. Use of a Buster or Elizabethan collar is recommended postoperatively to prevent self-excoriation of the surgical area.

b. Spastic (physiological). Spastic entropion refers to entropion caused by spasm of the orbicularis oculi muscle in response to ocular pain or irritation. Ocular pain may cause severe blepharospasm which in some instances results in entropion. Secondary trichiasis occurs from eyelid hair rubbing against the cornea, which causes further ocular pain, additional blepharospasm and subsequently more pronounced entropion. The spastic component of entropion is determined by instilling topical anesthetic; spastic entropion is that portion of entropion relieved by topical anesthetic. If persisting for long duration, spastic entropion may become cicatricial secondary to tarsal fibrosis. Treatment is directed at removing the cause of ocular pain and placement of temporary tacking sutures.

c. Cicatricial. Cicatricial entropion results from trauma (including previous eyelid surgery) or from chronic spastic entropion. Cicatricial entropion is less common and surgical correction more difficult to achieve long-term correction.

2. Ectropion. Ectropion is eversion of the eyelid margin. This may result in exposure of the conjunctiva (usually lower) but is usually less serious than entropion. The most common cause of ectropion is conformational ectropion that occurs in Spaniel and hound breeds, and surgical correction is not only unnecessary but may exclude a dog from competitive show. Neuroparalytic ectropion following facial nerve damage can occur but is uncommon. Clinical signs of ectropion include visualization of the lower conjunctiva, and may include conjunctival hyperemia, keratitis, and mucus accumulation in the lower conjunctival cul-de-sac. Ectropion frequently occurs secondary to instability of the lateral canthus and is misdiagnosed as primary ectropion. In such instances, correction of ectropion alone will not correct the abnormality. Correction of ectropion is indicated only when eyelid function (ability to blink) is intact and abnormalities of the cornea are evident. Surgical correction by full-thickness wedge resection is simple and effective. A blepharoplasty can also be used for cicatricial ectropion. This elevates skin overlying scar tissue and allows the eyelid margin to retract to a more normal position.

3. Instability of the Lateral Canthus. This condition may be attributable to a primary defect or laxity of the retractor anguli oculi lateralis muscle and/or the lateral canthal tendon. Many affected dogs have abnormal tarsal plate development. Concurrent entropion and ectropion of one or both eyelids is common. The normal position of the lateral canthus varies by breed but is usually lateral and slightly ventral to a horizontal line drawn across the cornea. This frequently occurs in the St. Bernard, Newfoundland, Chow chow, Bloodhound, and Bullmastiff, but can occur in most breeds. Correction involves creation of new lateral canthus (lateral canthoplasty), removal of excess eyelid tissue and/or primary entropion repair.2

4. Brow Ptosis - Certain canine breeds have a very heavy brow which induces secondary entropion of the upper eyelid. When present and inducing entropion and secondary corneal abnormalities, a brow lift procedure is indicated. Various surgical procedures have been described to correct brow ptosis. I recommend that you consider referring dogs to a veterinary ophthalmologist for brow ptosis surgery.

5. Lagophthalmos. The inability to blink may result in exposure keratitis. Facial nerve dysfunction (idiopathic, traumatic following bulla osteotomy) are common causes. Temporary lagophthalmos (facial neuropraxia) after total ear canal ablation and bulla osteotomy surgery is common. If eyelid function is absent, the cornea should be kept moist using a bland, preservative-free tear ointment. Permanent lagophthalmos may require permanent lateral tarsorrhaphy surgery to decrease tear evaporation by decreasing the tear film meniscus between the upper and lower eyelids.

Eyelash Abnormalities

1. Distichiasis. Distichia are cilia that arise from Meibomian gland openings (Figure 4). Both upper and lower eyelids can be affected. Animals with distichiasis must be evaluated carefully; the mere presence of distichia is not justification for removal (e.g., most American Cocker spaniels). Treatment is indicated only when cilia are inducing corneal irritation (ulceration, vascularization, fibrosis, pigmentation, epiphora or persistent blepharospasm). Soft, fine, tapered or silky cilia which float in the tear film usually do not cause irritation. Correction involves electroepilation or cryoepilation. Thermocautery is contraindicated as it destroys normal eyelid structures and results in scarring. Manual epilation is effective only temporarily but may aide in determining if the cilia are causing clinical signs or disease.

2. Districhiasis. Districhiasis is defined as two or more cilia emanating from a single Meibomian gland opening. For treatment see Distichiasis above.

3. Ectopic cilia  Ectopic cilia is a hair or bundle of hairs that emanate through the palpebral conjunctiva (usually the upper central eyelid) usually near the base of the Meibomian gland. Ectopic cilia are usually diagnosed in young dogs; they are exceedingly rare in cats. The cilia cause corneal irritation or ulceration in the area that they overlie, and are usually located in the perilimbal cornea. Spastic entropion and epiphora are common. Examination with magnification may reveal a pigmented area of conjunctiva surrounding the orifice of the ectopic cilia. Excision of the palpebral conjunctiva, including the cilia and its follicle, is usually curative.

4. Trichiasis. Trichiasis is a cilia which originates from a normal location that is misdirected toward the cornea, conjunctiva, or eyelids. This may result secondary to entropion, or as a primary entity (e.g., excessive nasal skin folds in brachycephalic breeds). If trichiasis occurs secondary to entropion, a modified Hotz-Celsus procedure may be indicated. If trichiasis results from nasal skin folds contacting the cornea, excision of skin folds or medial canthoplasty is the treatment of choice.

Inflammatory Eyelid Diseases

1. Chalazion (ka-lay-zee-on). Retention or blockage of oily secretions from the Meibomian gland extravasates into surrounding eyelid tissues and induce a granulomatous inflammatory response. Clinically a chalazion appears as a firm, nodular, yellow-gray mass through the palpebral conjunctival surface (Figure 5) and is painless. Chalazia occur more frequently in dogs than in cats and most commonly occur secondary to a Meibomian gland adenoma which block secretion of the Meibomian gland. Treatment requires surgical curettage through the conjunctiva.2 The skin is not incised. Aftercare consists of topical antibiotic-steroid solution for 5-7 days.

2. Hordeolum (stye). A hordeolum is inflammation of the glands of Zeis or Moll (external hordeolum) or Meibomian gland (internal hordeolum). The hallmark clinical sign of a hordeolum is pain upon manipulation. Treatment includes drainage, topical antibiotic ointment, and hot packs.

3. Meibomitis - Staphylococcal infection usually associated with generalized dermatoses. The Meibomian glands exude a yellow, purulent material instead of a clear oily secretion (Figure 6). Examination of the conjunctival surface shows linear yellow-white inflammatory infiltrates perpendicular to the eyelid margin. Material should be expressed for bacterial culture and susceptibility testing. Topical and systemic antibiotics and warm compresses are indicated. Oral corticosteroids may also be necessary.

4. Blepharitis - inflammation of the eyelids, especially the eyelid margins, is common but may be overlooked if it is part of a more generalized dermatitis. 3

a. Etiologies:

1) Bacterial - most commonly Staphylococcus aureus. Juvenile pyoderma/puppy strangles in puppies or staphylococcal hypersensitivity in the adult. Topical and systemic antibiotics are indicated. Systemic corticosteroids in refractory or severe acute cases are also indicated. In generalized dermatological disease, the underlying cause should be established and treated accordingly.

2) Parasitic - mites, e.g., Demodex or Sarcoptes in young dogs, Notoedres in cats.

3) Metabolic - seborrheic blepharitis associated with generalized seborrhea or allergic dermatitis.

4) Actinic - related to sunlight.

5) Fungal - dermatomycoses.

6) Traumatic - lye, acids, fire.

7) Immune-mediated/allergic - pemphigus, toxic epidermal necrolysis, atopy.

8) Viral - FHV-1 in young kittens. Substantial cicatricial lid deformation and corneal fibrosis may result.

b. Diagnosis and treatment: Diagnosis requires testing similar to that for other dermatologic diseases including skin scrapings, cultures (bacterial and fungal), and biopsy if necessary. Treatment is based on diagnosis of the underlying cause.

5. Blepharedema. Blepharedema is a clinical sign rather than a disease entity. Causes include trauma, allergies/hypersensitivity reactions, insect bites, secondary to orbital cellulitis/abscess, and vasculitis. Treatment depends on the underlying cause but may consist of corticosteroids (topical and systemic), non-steroidal anti-inflammatory drugs, antihistamines, and topical and oral antibiotics (e.g., secondary to cellulitis).

Traumatic Eyelid Abnormalities

Eyelid lacerations occur frequently in many domesticated animals. Bite wounds or automobile trauma is the most common causes. The animal must be carefully evaluated for concurrent systemic abnormalities. The globe should also be examined thoroughly to determine if concurrent ocular trauma is evident. Eyelid lacerations should be repaired as soon as possible. Eyelids are extremely vascular and post-traumatic swelling can be extensive. However, beneficial properties of highly vascular tissues include rapid rate of healing and resistance to infection. When lacerations of the medial aspect of the eyelids occurs, the lacrimal puncta should be cannulated and flushed to determine if the nasolacrimal duct is involved. Eyelid wounds should be cleaned of all debris and prepared with a dilute Betadine solution. The wound should not be debrided (or minimally debrided). If the wound is not fresh or is extremely swollen and edematous, the wound should be irrigated gently. Application of a topical broad-spectrum antibiotic and atropine should be applied to the globe and lids, and a nitrofurazone bandage placed for 12 to 24 hours. This will provide dramatic improvement in the appearance of the wound. The wound should then be cleansed be apposed in a two-layer closure to ensure adequate physiologic and cosmetic results. 5-0 or 6-0 polyglactin 910 is recommended to oppose the tarsoconjunctiva, taking care to bury the knots in the tissue to avoid corneal irritation or damage. Simple interrupted sutures of 4-0 or 5-0 silk are used for the skin.2 The first suture is placed at the eyelid margin in a figure-8 pattern to ensure accurate apposition. The next suture is placed 1-2 mm from the appositional suture. The remaining wound is closed with simple interrupted sutures. Aftercare consists of topical and systemic antibiotics for 7-10 days.

Meibomian (Sebaceous) Adenoma. The most common eyelid neoplasm of dogs is a Meibomian adenoma.4 This neoplasm arises from the Meibomian gland but is observed at the eyelid margin, near the Meibomian orifice (Figure 5). Treatment is recommended when corneal irritation results from contact. Simple excision parallel to the eyelid margin is not effective. Treatment requires debulking and adjuvant cryosurgery or full-thickness eyelid resection. The amount of lid shortening that may be done is dependent upon the conformation of the lids in a given breed. Very little tissue may be removed without inducing iatrogenic ectropion or entropion in canine breeds that have a taut lid-to-globe conformation (Miniature poodle, Bichon Frise, other brachycephalics).

Melanoma. Lid melanomas are usually superficial and benign. They occur most frequently in older dogs of heavily pigmented breeds. They are usually slow growing, may be multiple, and are cryosensitive.

Papilloma - Papilloma are usually superficial and affect young dogs. Surgical removal is recommended if a rapid increase in size or irritation to the cornea occurs. Papilloma are cryosensitive but may spontaneously regress in young dogs.

Adenocarcinoma - Adenocarcinoma can not be differentiated from Meibomian gland adenoma based on clinical appearance. Although histologically malignant, benign biological behavior is the rule. Adenocarcinoma are also cryosensitive.

Histiocytoma. Histiocytoma is primarily a tumor of young growing dogs. Histiocytoma has a characteristic clinical appearance in the dog it is always raised, less than 1 cm in diameter, pink in color, hairless, and has a characteristic rapid growth pattern (Figure 7). Histiocytoma frequently regresses spontaneously between 3 and 5 weeks after it appears.
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