Blepharitis
Blepharitis is the inflammation of the outer (skin) and middle (muscle, connective tissue, and glands) portions of the eyelid, usually with secondary inflammation of the palpebral conjunctiva.
Anterior—most commonly associated with bacterial infection or self-trauma.
Posterior—disorders of the meibomian glands.
PATHOPHYSIOLOGY
Same as virtually every condition that affects the skin in general.
Mechanisms of inflammation—immune-mediated, infectious, endocrine mediated, self-and external trauma, parasitic, radiation, and nutritional.
An inflammatory response is often exaggerated because eyelid conjunctiva is rich in mast cells and densely vascularized.
Meibomian gland dysfunction—common; bacterial lipases alter meibomian lipids so they plug the gland; they also produce irritating fatty acids, enhance bacterial growth, and destabilize the tear film.
SYSTEMS AFFECTED
Ophthalmic
SIGNS
Serous, mucoid, or mucopurulent ocular discharge.
Blepharospasm.
Eyelid hyperemia, edema, and thickening.
Pruritus.
Excoriation.
Depigmentation—skin; hair.
Alopecia.
Swollen, cream-colored meibomian glands.
Elevated, pinpoint meibomian gland orifices.
Abscesses.
Scales and crusts.
Papules or pustules.
Single or multiple nodular hyperemic swellings.
Concurrent conjunctivitis and/or keratitis.
In Siamese-type cats with color points, chronic blepharitis often causes lightening of hair on affected lids due to increased temperature of the skin.
CAUSES
Congenital
Eyelid abnormalities—may promote self-trauma or moist dermatitis.
Prominent nasal folds, medial trichiasis, and lower lid entropion—shih tzu, Pekingese, English bulldog, Lhasa apso, pug; Persian and Himalayan cat.
Distichia—shih tzu, pug, golden retriever, Labrador retriever, poodle, English bulldog.
Ectopic cilia.
Lateral lid entropion—shar-pei, chow chow, Labrador retriever, rottweiler; adult cats (rare).
Lagophthalmos—brachycephalic dogs; Persian, Himalayan, and Burmese cats.
Deep medial canthal pocket—dolichocephalic dogs.
Dermoids—rottweiler, dachshund, and others; Burmese cat.
Allergic
Type I (immediate)—atopy, food, insect bite, inhalant, Staphylococcus hypersensitivity.
Type II (cytotoxic)—pemphigus, pemphigoid, drug eruption.
Type III (immune complex)—SLE; Staphylococcus hypersensitivity; drug eruption.
Type IV (cell-mediated)—contact and flea bite hypersensitivity; drug eruption.
Bacterial
Hordeolum—localized abscess of eyelid glands, usually staphylococcal; may be external (sty in young dogs, involving glands of Zeis) or internal (in old dogs, involves one or more meibomian glands).
Generalized bacterial blepharitis and meibomianitis—usually Staphylococcus or Streptococcus.
Pyogranulomas.
Staphylococcus hypersensitivity—young and old dogs.
Neoplastic
Sebaceous adenomas and adenocarcinomas—originate from the meibomian gland.
Squamous cell carcinoma—white cats.
Mast cell—may masquerade as a swollen, hyperemic lesion.
Other
External trauma—eyelid lacerations; thermal or chemical burns.
Mycotic—dermatophytosis; systemic fungal granulomas.
Parasitic—demodicosis; sarcoptic mange; Cuterebra and Notoedres cati. Note: Demodex injai has a propensity for sebaceous glands and can be associated with meibomian gland dysfunction in dogs, including chalazia and granulomatous blepharitis.
Chalazia (singular, chalazion)—sterile, yellow-white, painless meibomian gland swellings caused by a granulomatous inflammatory response to escape of meibum into surrounding eyelid tissue.
Nutritional—zinc-responsive dermatosis (Siberian husky, Alaskan malamute, puppies); fatty acid deficiency.
Endocrine—hypothyroidism (dogs); hyperadrenocorticism (dogs); diabetic dermatosis.
Viral—chronic blepharitis in cats secondary to FHV-1.
Irritant—topical ocular drug reaction; nicotine smoke in the environment; after parotid duct transposition.
Familial canine dermatomyositis—collie and Shetland sheepdog.
Nodular granulomatous episclerokeratitis—fibrous histiocytoma and collie granuloma in collies; may affect the eyelids, cornea, or conjunctiva.
Eosinophilic granuloma—cats; may affect eyelids, cornea, or conjunctiva.
Eyelid contact with tear overflow and purulent exudate (tear burn).
Conjunctivitis.
Keratitis.
Dry eye.
Dacryocystitis.
Orbital disease.
Radiotherapy.
Drug contact irritant—any drug, often neomycin.
Idiopathic—particularly in cats with chronic idiopathic conjunctivitis (especially Persians and Himalayans).
RISK FACTORS
Breed predisposition to congenital eyelid abnormalities, e.g., entropion, ectropion, etc.
Hypothyroidism—may promote chronic bacterial disease in dogs.
Canine seborrhea—may promote chronic generalized meibomianitis, with a predisposition for Demodex injai infection.
DIAGNOSIS
DIFFERENTIAL DIAGNOSIS
Clinical signs are diagnostic.
CBC/BIOCHEMISTRY/URINALYSIS
Usually non-diagnostic unless metabolic cause (e.g., diabetic dermatosis).
OTHER LABORATORY TESTS
Indicated for the suspected systemic disorder.
Consider tests for hypothyroidism.
DIAGNOSTIC PROCEDURES
If possible, avoid topical anesthetic or fluorescein before obtaining culture.
Cytology—deep skin scrapings; conjunctival scrapings; expressed exudate from meibomian glands and pustules.
Dermatophyte culture—deep skin scrapings.
Wood’s light evaluation—skin.
KOH preparation—skin scrapings.
Aerobic bacterial culture and sensitivity—exudate from the skin; conjunctiva; expressed exudate from meibomian glands and pustules; often will not recover Staphylococcus from patients with chronic meibomianitis and suspected Staphylococcus hypersensitivity.
IFA or PCR for FHV-1 and Chlamydia—conjunctival scrapings from cats with primary conjunctivitis or keratitis.
Eye examination—potential inciting cause; corneal ulcer; foreign body; distichia; ectopic cilia; dry eye.
Ancillary ocular tests— fluorescein application; Schirmer tear test.
Thorough medical history and dermatologic examination—help identify generalized dermatologic disease.
Full-thickness wedge biopsy of the eyelid—histologic evaluation.
Direct immunofluorescence for autoimmune disease; intradermal skin testing, RAST, ELISA, and food elimination diet for hypersensitivity-induced disease.
Do not underestimate the value of referral to a dermatologist for refractory cases, especially when atopy is suspected.
PATHOLOGIC FINDINGS
Routine histopathology is often non-diagnostic in chronic disease.
Carefully select patients based on history, ophthalmic exam, and response to medical therapy.
TREATMENT
NURSING CARE
Secondary disease—treat primary disease.
Suspected self-trauma—Elizabethan collar.
Topical gentamicin, neomycin, Terramycin, and most ointments—may cause an irritant blepharoconjunctivitis (rare); withdrawal of agent may resolve the condition.
Cleanse eyelids—to remove crusts; warm compresses applied for 5–15 minutes 3–4 times daily, avoiding ocular surfaces; saline lactated Ringer’s solution, or a commercial ocular cleansing agent (e.g., I-Lid n Lash); must clip periocular hair short.
DIET
Only with food allergy-induced disease.
CLIENT EDUCATION
In cats with FHV-1-related blepharitis inform the client that there is no cure and that clinical signs often recur when the animal is stressed.
Inform the client that there is no cure for FHV-1 and that clinical signs often recur when the animal is stressed.
SURGICAL CONSIDERATIONS
Temporary everting eyelid sutures—spastic entropion; or in puppies before permanent surgical correction.
Repair eyelid lacerations.
Lancing—large abscesses only; lance and curette hordeola that resist medical treatment and chalazia that have hardened and come to a point, causing keratitis; manually express infected meibomian secretions.
MEDICATIONS
DRUG(S)
Antibiotics
Systemic—generally required for effective treatment of bacterial eyelid infections; may try amoxicillin-clavulanic acid or cephalexin; 20 mg/kg q8h.
Topical—may try neomycin, polymyxin B, and bacitracin combination or chloramphenicol.
Congenital
Topical antibiotic ointment—q6–12h; until surgery is performed to prevent frictional rubbing of eyelid hairs or cilia on the ocular surface
Saline, lactated Ringer’s solution, or ocular irrigant—regularly flush deep medial canthal pocket debris.
External Trauma
Topical antibiotic ointment—q6–12h; for spastic entropion secondary to pain and blepharospasm to reduce friction until entropion is surgically relieved.
Systemic antibiotics indicated.
Allergic
Staphylococcus hypersensitivity blepharitis—systemic broad-spectrum antibiotics and systemic corticosteroids (prednisolone 0.5 mg/kg q12h for 3–5 days, then taper); many patients respond dramatically to systemic corticosteroids alone. Systemic cyclosporine if refractory to corticosteroids (5 mg/kg PO q24h until remission, then q48–72h).
Infected meibomian glands—oral tetracycline (15–20 mg/kg PO q8h) or doxycycline (3–5 mg/kg PO q12h) or cephalexin (22 mg/kg q8h) for at least 3 weeks (the former two are lipophilic and cause decreased production of bacterial lipases and irritating fatty acids); topical polymyxin B and neomycin with 0.1% dexamethasone (q6–8h to the eye) or topical 0.02% tacrolimus compounded ointment (q8–12h). Note: Some affected dogs might also have concomitant Demodex injai infection and require treatment for demodecosis.
Failure of treatment—may try injections of commercial Staphylococcus aureus bacterin (Staphage Lysate).
Eyelid lesions associated with puppy strangles—usually benefit from treatment of the generalized condition.
Atopy (see Atopy); consider Janus kinase inhibitor (oclacitinib; Apoquel) to control pruritus and self-trauma.
Bacterial
Based on culture and sensitivity testing.
While results are pending—topical polymyxin B and neomycin with 0.1% dexamethasone ointment (q4–6h); plus a systemic broad-spectrum antibiotic.
Mycotic
Microsporium canis infection—usually self-limiting; treatment includes 2% miconazole cream, 1% clotrimazole cream, or diluted povidone-iodine solution (1 part to 300 parts saline) applied q12–24h for at least 6 weeks; do not use lotions.
Parasitic
Demodicosis—localized disease: see Demodicosis. Some dogs require systemic treatment with moxidectin, ivermectin, or milbemycine oxime.
Notoedres infection—lime sulfur dips.
Sarcoptic mange—same as for generalized disease.
Idiopathic
Clinical signs often controlled with topical polymyxin B and neomycin with 0.1% dexamethasone (q8–24h or as needed); occasionally may also need systemic prednisolone (0.5 mg/kg q12h for 3–5 days, then taper) and/or a systemic antibiotic.
CONTRAINDICATIONS
Topical corticosteroids—do not use with corneal ulceration.
Many cats with presumed idiopathic blepharoconjunctivitis have FHV-1 infection; topical and systemic corticosteroids may exacerbate the infection.
Oral tetracycline and doxycycline—do not use in puppies and kittens.
Neomycin—avoid topical use if suspect it is causing blepharitis.
PRECAUTIONS
Ectoparasitism—wear gloves; do not contact ocular surfaces with a drug topically applied to the skin; apply artificial tear ointment to the eyes for protection.
POSSIBLE INTERACTIONS
Staphylococcal bacterin for Staphylococcus hypersensitivity—anaphylactic reaction (rare).
FOLLOW-UP
PATIENT MONITORING
Depends on the cause and mode of therapy.
Bacterial—treated with systemic and topical treatment for at least 3 weeks; should notice improvement within 10 days.
Most common causes of treatment failure—use of subinhibitory antibiotic concentrations; failure to correct one or more predisposing factors; stopping medications too soon.
PREVENTION/AVOIDANCE
Depends on cause.
POSSIBLE COMPLICATIONS
Cicatricial lid contracture—results in trichiasis, ectropion, or lagophthalmos.
Spastic entropion—because of blepharospasm and pain.
Inability to open eyelids—owing to matting of discharge and hair.
Qualitative tear film deficiency—the result of loss of proper meibum secretion.
Recurrence of a bacterial infection or FHV-1 blepharoconjunctivitis.
EXPECTED COURSE AND PROGNOSIS
Depends on the cause.
Visit your veterinarian as early recognition, diagnosis, and treatment are essential.