Evaluation of clinical characteristics and bacterial isolates in dogs with bacterial keratitis: 97 cases (1993-2003).

Objective: To evaluate clinical characteristics and breeds affected with bacterial keratitis and compare patterns of resistance in bacterial isolates over time in dogs.

Design: Retrospective cross-sectional study.

Animals: 97 dogs with bacterial keratitis.

Procedure: Dogs with bacterial keratitis were identified from teaching hospital medical records at the Universities of Tennessee and Florida during the years 1993 to 2003. Data were collected pertaining to breed, Schirmer tear test results, treatments administered at the time of initial examination, bacterial species isolated, and resistance to selected antimicrobials.

Results: 66% of the dogs were brachycephalic, 54% had tear production < 15 mm/min, and 29% were receiving a corticosteroid at the time of initial examination. The most common bacteria isolated were Staphylococcus intermedius (29%), beta-hemolytic Streptococcus spp (17%), and Pseudomonas aeruginosa (21%). Staphylococcus intermedius isolates had limited resistance to certain antimicrobials. More than 80% of beta-hemolytic Streptococcus spp isolates were resistant to neomycin, polymyxin B, and tobramycin. Isolates of P aeruginosa were susceptible to tobramycin and gentamicin and had limited resistance to ciprofloxacin and enrofloxacin. Among bacterial species isolated, there was no evidence of development of antimicrobial resistance over time.

Conclusions And Clinical Relevance: Data suggested that administration of ciprofloxacin or a combination of a first-generation cephalosporin and tobramycin may be used in the treatment of bacterial keratitis while awaiting results of bacterial culture and susceptibility testing. Evidence suggests that current methods of medical management of bacterial keratitis are not associated with increased antimicrobial resistance.