Melting ulcer in the dog: Pseudomonas and anti-proteases

Question

3-year-old French Bulldog treated for 4 days with dexamethasone–tobramycin eye drops for a 'red eye'. It now has an ulcer with gelatinous, greyish stroma that appears to sag, a yellow-white infiltrate, miosis and severe pain. Corneal cytology shows degenerate neutrophils and Gram-negative rods.

Which treatment plan is most appropriate?

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A. Continue the combination drop and add atropine for the reflex uveitis

The topical corticosteroid is exactly what has favoured the infection and collagenolysis. It must be stopped immediately.

B. Stop the corticosteroid, sample for culture, intensive topical antibiotic effective against Pseudomonas, topical anti-proteases (autologous serum or EDTA), oral doxycycline, atropine and a systemic NSAID

Correct. Both the bacterium and the proteases (those of Pseudomonas and the host's own matrix metalloproteinases) must be stopped. Autologous serum and EDTA inhibit proteases on the surface; oral doxycycline inhibits metalloproteinases. If the ulcer is deep, consider surgery.

C. Topical chloramphenicol three times daily for a week

Pseudomonas aeruginosa is usually resistant to chloramphenicol, and three times daily is far too infrequent for an infected, melting ulcer.

D. Autologous serum as the sole treatment, since the damage is caused by collagenases rather than the bacterium

Anti-proteases are essential, but without controlling the infection protease production continues. Treatment must be combined.

lightbulb Key takeaway

Never prescribe an ocular corticosteroid without doing fluorescein first. A gelatinous ulcer with infiltrate is an emergency: cytology, culture, frequent antibiotic against Gram-negatives and anti-proteases from day one.

Which treatment plan is most appropriate?

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