When seemingly routine corneal ulcers in dogs fail to heal in a normal period (i.e. seven to 10 days), many veterinarians engage in musical chairs treatment, prescribing one topical antibiotic and then another.
Unless specific signs of bacterial infection are present (e.g. progressive stromal loss, a leukocytic infiltrate in the stroma, a melting component associated with the ulcer), switching
topical antibiotics is a waste of time and money. Instead, the ulcers need to be reevaluated to determine the reason for delayed
healing. Common causes of nonhealing corneal ulcers in dogs, besides infection, include entropion, lagophthalmos, ectopic
cilia, keratoconjunctivitis sicca, a foreign body, and superficial corneal erosion syndrome (i.e. refractory, or Boxer, ulcer). Changing the topical antibiotic will not remedy any of these causes. If you genuinely suspect
a bacterial infection, perform a corneal scraping for cytologic examination, and submit a swab for bacterial and fungal culture
and antimicrobial sensitivity testing to determine the appropriate topical antibiotic.
Steven R. Hollingsworth, DVM, DACVO
Department of Surgical and Radiological Sciences
School of Veterinary Medicine
University of California-Davis
Davis, CA 95616