Ulcerative keratitis

From Dog
Indolent corneal ulcer[1]
Corneal ulcer due to Pseudomonas spp infection[2]

Corneal ulcer (ulcerative keratitis) is a common ophthalmic disease of the canine eye.

This condition, which involves damage to the cornea with subsequent erosion of the epithelial layer, can result in considerable damage and pain to the eye, with conjunctivitis, subsequent scar formation, anterior uveitis, symblepharon and vision loss.

The corneum is divided into three layers:

  • Epithelium - the thin membrane on the outer surface of the cornea
  • Stroma - the layers of cells between the inner and outer membranes
  • Descemet's membrane - the thin membrane on the inner surface of the cornea

Injury to the cornea that damages only the epithelium is called a corneal abrasion. Injury that extends through the epithelium and into the stroma is called a corneal ulcer. A deep ulcer that extends down to Descemet's membrane can result in a descemetocele.

There are many causes of ulcerative keratitis, including:

  • Trauma, chemical burns, insect bites[3]
  • Breed predisposition
- Chronic superficial keratitis in German Shepherds
- Staphylococcus aureus[5]
- Pseudomonas aeruginosa[6]
- Neisseria spp[7]
- Corynebacterium spp
- Enterococcus spp
- Curvularia spp[9]
- Canine herpesvirus[10]
- Perilimbal squamous cell carcinoma[11]
- Ocular melanoma
- Capecitabine

Affected dogs frequently show blepharospasm, varying degrees of epiphora, photophobia and on ophthalmic exmaination, a deficit in the cornea is seen, especially after staining with flourescein dye. Corneal sequestrum may develop in some cases, characterized by a brownish plaque over the ulcerated lesion. These are relatively rare compared to cats[12].

With Pseudomonas spp infections, the keratitis can quickly worsen, leading to blepharitis, conjunctivitis, dacryocystitis, keratitis, scleritis, chorioretinitis, endophthalmitis and orbital cellulitis[13].

Treatment requires a number of surgical options such as tarsorrhaphy, debridement and grid keratotomy, conjunctival graft and prosthetic grafts[14].

Use of topical antimicrobial ophthalmic ointment is indicated in most cases, especially with refractory cases[15].

References

  1. Puppyer
  2. Ledbetter EC et al (2009) Pathogenic phenotype and genotype of Pseudomonas aeruginosa isolates from spontaneous canine ocular infections. Invest Ophthalmol Vis Sci 50(2):729-736
  3. Brutlag AG et al (2011) Corneal ulceration in a dog following exposure to the defensive spray of a walkingstick insect (Anisomorpha spp.). J Vet Emerg Crit Care (San Antonio) 21(4):382-386
  4. Sansom J & Blunden T (2010) Calcareous degeneration of the canine cornea. Vet Ophthalmol 13(4):238-243
  5. Tajima K et al (2012) Methicillin-resistant Staphylococcus aureus keratitis in a dog. Vet Ophthalmol Nov 5
  6. Santos TM et al (2011) Isolation and characterization of two bacteriophages with strong in vitro antimicrobial activity against Pseudomonas aeruginosa isolated from dogs with ocular infections. Am J Vet Res 72(8):1079-1086
  7. Wang L et al (2008) Investigation of bacterial microorganisms in the conjunctival sac of clinically normal dogs and dogs with ulcerative keratitis in Beijing, China. Vet Ophthalmol 11(3):145-149
  8. Grundon RA et al (2010) Keratomycosis in a dog treated with topical 1% voriconazole solution. Vet Ophthalmol 13(5):331-335
  9. Ben-Shlomo G et al (2010) Curvularia keratomycosis in a dog. Vet Ophthalmol 13(2):126-130
  10. Gervais KJ et al (2012) Acute primary canine herpesvirus-1 dendritic ulcerative keratitis in an adult dog. Vet Ophthalmol 15(2):133-138
  11. Wiggans KT et al (2012) Malignant transformation of a putative eyelid papilloma to squamous cell carcinoma in a dog. Vet Ophthalmol Aug 9
  12. Bouhanna L et al (2008) Corneal stromal sequestration in a dog. Vet Ophthalmol 11(4):211-214
  13. Eifrig CW et al (2003) Endophthalmitis caused by Pseudomonas aeruginosa. Ophthalmology 110(9):1714–1717
  14. Goulle F (2012) Use of porcine small intestinal submucosa for corneal reconstruction in dogs and cats: 106 cases. J Small Anim Pract 53(1):34-43
  15. Chandler HL et al (2010) In vivo effects of adjunctive tetracycline treatment on refractory corneal ulcers in dogs. J Am Vet Med Assoc 237(4):378-386