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Pannus (Chronic Superficial Keratitis) 749

corneal lesions commencing in the lateral to Advanced or Confirmatory Testing cyclosporine or tacrolimus until corneal
ulcer has healed.
ventrolateral cornea and progressively involv- • Usually not required; diagnosed by clinical • Granuloma at site of subconjunctival
VetBooks.ir • Conjunctivitis present in most cases other causes of corneal vascularization and Recommended Monitoring Diseases and Disorders
findings, dog’s signalment, and ruling out
ing the medial, ventral, and dorsal aspects of
corticosteroid injection
the cornea, including the central cornea
pigmentation
• Multifocal white, crystalline lipid deposits
often present at the leading edge of the • Cytologic exam of corneal and conjunctival • Response to therapy is monitored every 3-4
swabs/scrapings reveals lymphocytes and
corneal lesions plasma cells. weeks initially, then every 4-6 weeks. Pannus
• ± Third eyelid involvement as evidenced by • If a keratectomy is performed, histopatho- is in remission when the active vessels have
pink proliferative lesions and depigmentation logic findings consist of lymphocyte, plasma receded. The pigment takes months to thin
along leading edge of third eyelid (atypical cell, macrophage, and melanocytic cell and never completely resolves if severe.
pannus) infiltrations with corneal vascularization • Once stable, the patient is reevaluated every
• Early pannus and fibroplasia. 3-6 months.
○ Vascularization and/or pigmentation at
lateral to ventrolateral cornea adjacent to TREATMENT PROGNOSIS & OUTCOME
limbus
○ Progresses centrally Treatment Overview • Pannus is a chronic disorder that typically
• Chronic pannus The treatment goal is to suppress the disease responds to intensive medical therapy.
○ Fleshy lesion (i.e., granulation tissue) process with intensive initial treatment and to • Maintenance therapy is needed to keep the
with corneal vascularization and/or maintain the disease remission with continued disease in remission.
pigmentation therapy. Generally, treatment with topical
○ Entire cornea may be affected, predispos- corticosteroids is initiated and then tapered PEARLS & CONSIDERATIONS
ing the animal to blindness. as treatment with cyclosporine or tacrolimus
is initiated when the pannus is in remission. Comments
Etiology and Pathophysiology • A common error in treatment is failure to
• Increased expression of major histocom- Acute General Treatment provide intensive therapy in the early stages
patibility complex (MHC) class II genes • Topical corticosteroids (dexamethasone 0.1% of disease.
(particularly dog leukocyte antigen [DLA] solution or ointment or prednisolone acetate • The disease should be treated proactively
class II genes) indicates pannus is an 1% suspension) q 6-8h for 3 weeks, followed with topical corticosteroids ± cyclosporine
immune-mediated disease. by slow reduction to a maintenance dose or tacrolimus, and the frequency should
• Tissue-specific antigens in the cornea are • Cyclosporine 0.2% ointment or 0.5%-2% be slowly reduced over weeks to reach a
altered by ultraviolet radiation exposure. solution topically q 12h or tacrolimus maintenance therapy.
• Dogs with pannus develop a hypersensitivity 0.02%-0.03% ophthalmic ointment or • Pannus is a chronic disease that requires
response to corneal proteins, predisposing aqueous suspension q 12h lifelong treatment.
them to chronic inflammation.
• Pannus is more rapidly progressive and severe Chronic Treatment Prevention
in young dogs (<3 years of age). • Requires lifelong therapy • Owners should limit exposure of pets to
• Maintenance therapy consists of topical oph- ultraviolet light.
DIAGNOSIS thalmic corticosteroids and/or cyclosporine • They should also avoid breeding affected or
or tacrolimus q 12-24h or lowest effective closely related dogs.
Diagnostic Overview dose. Best to discontinue corticosteroids
Diagnosis is based on the clinical presentation if possible to decrease risk of lipid corneal Technician Tips
of typically bilateral corneal vascularization and degeneration. Most dogs with severe or blinding pannus gain
pigmentation in large-breed dogs. • Maintenance of remission is possible in functional vision with intense and prolonged
some dogs with once daily application of treatment. Continued owner compliance is
Differential Diagnosis cyclosporine. very important.
• Keratoconjunctivitis sicca • For nonresponsive and severe cases, clinicians
• Other causes of corneal vascularization can consider Client Education
(p. 212) ○ Adjunctive subconjunctival injections of • Pannus is an immune-mediated disease that
• Other causes of corneal pigmentation corticosteroids (e.g., methylprednisolone is manageable but not curable.
(p. 206) acetate, 4-8 mg; triamcinolone acetonide • Lifelong treatment is required.
4-12 mg [dose depends on size of dog])
Initial Database q 2-3 weeks SUGGESTED READING
Complete ophthalmic exam (p. 1137): ○ Referral to veterinary ophthalmologist Ledbetter EC, et al: Diseases and surgery of the
• Schirmer tear test (typically normal with for beta-irradiation (i.e., strontium-90) canine cornea and sclera. In Gelatt KN, editor:
pannus) or superficial keratectomy Veterinary ophthalmology, ed 5, Ames, IA, 2013,
• Fluorescein dye application (typically no Wiley-Blackwell.
corneal dye retention with pannus but the Possible Complications AUTHOR: Phillip A. Moore, DVM, DACVO
dye may settle in rough areas in the cornea) • Corneal ulceration (p. 209); if it occurs, EDITOR: Diane V. H. Hendrix, DVM, DACVO
• Intraocular pressures normal (15-25 mm Hg) clinicians should discontinue corticosteroid
• Careful exam of the conjunctiva and cornea for the animal and commence/continue

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