Introduction: Keratoconjunctivitis sicca is a common and important eye disease of dogs and has been associated with the administration of trimethoprim-sulfonamide (TMS). The prevalence of KCS after TMS treatment has not been described at a population level and risk factors analysis is needed. Hypothesis: The prevalence of keratoconjunctivitis sicca (KCS) after trimethoprim-sulphonamide (TMS) therapy is rare and unrelated to dose. Animals: 2,243 dogs treated with TMS in clinical practice in Australia between 2012 and 2022.
Method: A retrospective cohort study of dogs evaluated in general veterinary practice in Australia with records in VetCompass Australia was performed. Natural language processing was used to detect dogs treated with TMS and those that subsequently developed KCS. Cox proportional hazards modelling was performed to investigate risk factors such as drug dose, duration of treatment, and patient-level characteristics (breed, age, sex).
Results: Four definitive cases of KCS and an additional 35 cases of possible KCS were detected (prevalence 1.8% [95% confidence interval [CI], 1.3-2.5%]). Median duration of TMS treatment was 10 days for both cases (Interquartile range [IQR], 7-17 days) and non-cases (IQR, 7-15 days). Median doses were 32 and 33 mg/kg/day for cases and non-cases, respectively. Trimethoprim-sulfonamide dose and duration of treatment were not associated with KCS. Some breeds were over-represented and older dogs were more likely to be affected (hazard ratio [HR], 1.076, 95% CI, 1.005-1.152. P = 0.04). Conclusion and clinical importance: Keratoconjunctivitis sicca is rare in dogs treated with TMS.
