A challenging case: A dog with nonhealing corneal ulcers - Veterinary Medicine
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A challenging case: A dog with nonhealing corneal ulcers
Corneal ulcers usually heal rapidly with appropriate treatment, but this Labrador developed two that were slow to heal. A technique used commonly in people—diamond burr superficial keratectomy—appeared to help in this case.



1. The left eye of the Labrador retriever in this report at the second presentation. Note the positive fluorescein stain and the ring of loose epithelium surrounding the ulcer margins. A characteristic halo of fluorescein stain is evident at the ulcer margins.
The dog was presented again about nine months later for evaluation of a superficial corneal ulcer of the left eye, which had been present for three weeks. The owner suspected that this ulcer had been caused by trauma. The referring veterinarian had treated the ulcer with an unknown topical antibiotic, atropine, and autogenous serum.

Ophthalmic examination and diagnostic testing

2. The left eye of the Labrador retriever in this report at the second presentation. A second area of ulceration is evident with fluorescein stain at the ventral cornea surface after slightly retracting the third eyelid.
The ophthalmic examination revealed that the dog had moderate iris atrophy and nuclear sclerosis in both eyes. The left eye showed moderate conjunctival hyperemia, mild blepharospasm, and epiphora. A 5-mm-diameter area of fluorescein stain retention was identified on the dorsonasal quadrant of the left cornea (Figure 1). After gentle retraction of the third eyelid, a second 4-mm-x-2-mm area of fluorescein stain retention was located ventronasally (Figure 2). Both areas of ulceration were superficial and appeared to have loose epithelium at their edges. The results of Schirmer tear tests and tonometry were normal in both eyes, and the remainder of the physical examination was unremarkable.


3. The dog in this report undergoing mechanical corneal débridement using a sterile cotton-tipped applicator soaked in dilute povidone-iodine solution.
SCCED of the left eye was diagnosed based on the clinical signs of this and the previous nonhealing chronic, superficial, corneal ulcer with loose corneal epithelial edges and the fact that both ulcers had been refractory to traditional corneal ulcer treatments. In addition, as was done during the previous episode of ulceration, other underlying causes for delayed healing were ruled out by the ophthalmic examination. Further evidence that supported the diagnosis of SCCED in this dog were the characteristic staining patterns, which consisted of poorly attached areas of corneal epithelium at the perimeter of the ulcers, under which the fluorescein stain leaked, leading to a dull-green halo of stain around the brighter-green staining center of the ulcer.1,2,6,7


4. A spontaneous chronic corneal epithelial defect in the dog in this report after mechanical débridement. The ulcer appears to be much larger because of the removal of nonadherent diseased epithelium.
After manually restraining the dog and applying several drops of topical proparacaine to the left cornea, the loose epithelium was mechanically débrided by using a sterile, cotton-tipped applicator soaked in dilute (1:50) povidone-iodine solution in a gentle circular motion (Figure 3). During the débridement, most of the loose epithelium that joined the two areas that had previously retained stain was removed. This procedure appeared to increase the area of corneal ulceration to about half of the corneal surface (Figure 4), but actually, it made it evident that the epithelium between the two apparent ulcers had not been firmly attached epithelium and needed to be removed to allow for proper healing.

After débridement, a superficial grid keratotomy was performed by using a 22-ga needle in a checkerboard pattern.8 The dog was sent home with topical 1% morphine ophthalmic drops to be administered three times daily to treat pain,5 neomycin-polymyxin-gramicidin ophthalmic ointment to be administered three times daily, and an Elizabethan collar to be worn until the dog was rechecked in seven days.


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