Sclera

Question 1

What are the two subcategories of episcleritis?

Answer 1

Primary and secondary. Primary can be subdivided into simple and NGE. Secondary episcleritis may result from diffuse, severe ocular disorders such as panophthalmitis, chronic glaucoma, or ocular trauma

Question 2

Describe the common ocular findings of NGE?

Answer 2

Multiple, elevated or single fleshy masses arising from the limbus and infiltrating the corneal stroma. NM involvement is common. Often bilateral in the collie.

Question 3

What are the common breeds affected by episcleritis?

Answer 3

Collie, Cocker Spaniel, Shetland Sheepdog

Question 4

What are the histopathologic features of NGE?

Answer 4

Histocytes, plasma cells, lymphocytes, fibrobastic cells. Epitheliod cell accumulation, reticulin fibre formation, neovascularisation with perivascular PMN cells

Question 5

What is the proposed pathogenesis of NGE?

Answer 5

Production of lymphokines by T-lymphocytes leading to chemotaxis of histiocytes

Question 6

Give two drugs that are T-cell suppressors

Answer 6

Azothioprine and ciclosporin.

Question 7

What is the azothioprine dose regime for NGE?

Answer 7

1.5–2.0mg/kg once daily for 3–10 days, and then at 0.75–1.00mg/kg once daily for 10–18 days

Question 8

What are the toxic side effects of azopthioprine?

Answer 8

GI toxicity (i.e., vomiting and bloody diarrhea), hepatotoxicosis, and myelosuppression

Question 9

When would CSA therapy be avoided?

Answer 9

If renal or hepatic insufficiency is present

Question 10

Describe CSA oral therapy?

Answer 10

The starting dose is 5 mg/kg/day for approximately 30 days (once the dog clinically responds well to treatment), then reduce to either 5 mg/kg po every other day or 2.5 mg/kg every 24 hours. Typical total treatment time is approximately 75–90 days (or longer if needed). Monitor CBC and serum chemistry profile at 2, 6, and 10 weeks into treatment

Question 11

What other therapies have been tried for NGE?

Answer 11

Intralesional steroid, subconjunctival steroid, cryotherapy, beta irradiation, lamellar keratectomy, oral administration of niacinamide (500 mg) and tetracycline (500 mg)

Question 12

How can scleritis be divided?

Answer 12

Non-necrotising granulomatous scleritis and granulomatous necrotising scleritis

Question 13

Describe the symptoms of scleritis

Answer 13

Pink lesions arising near the limbus
Pain, increased lacrimation, photophobia
\+/- adjacent corneal oedema
\+/- anterior uveitis and keratitis
\+/- infiltration of the choroid (and therefore retina)

Question 14

What systemic disease can scleritis be associated with?

Answer 14

Systemic collagen diseases

Question 15

What fundic changes can be seen with scleritis?

Answer 15

Focal or regional areas of retinochoroidal degeneration, with preretinal and vitreal exudates

Question 16

What are tests for systemic collagen disorders and are they usually useful for scleritis cases?

Answer 16

Canine rheumatoid factor, anti‐DNA‐antibody, lupus erythematosus cells. Usually negative

Question 17

Descirbe the typical lesion of canine scleritis?

Answer 17

Non-nodular, infiltrate of lymphocytes, plasma cells, epitheloid macrophages.
Granulomatous response can be found in the cornea
If uveitis present inflammation is non-granulomatous
Regions of scleral thinning or cystic spaces can form after several episodes

Question 18

Describe posterior segment lesions in non-necrotising granulomatous scleritis?

Answer 18

Granulomatous scleritis with adjacent non-granulomatous choroiditis.
Adjacent retinal degeneration- loss of outer layers of the retina with hypertrophy of RPE
Vitreal exudate is non-granulomatous

Question 19

Describe necrotising granulomatous scleritis

Answer 19

Rare in the dog
Bilateral, progressive, granulomatous scleritis with significant anterior uveitis
Affects both anterior and posterior segment and uveal tract
Poor response to treatment
B-cells and giant cells within granulomatous inflammation