A quantitative study of the effects of Tribrissen on canine tear production

The effect of trimethoprim-sulfadiazinea on Schirmer tear test (STT) values was studied in a population of dogs treated with the drug for a variety of medical and postsurgical conditions. The objectives of the study were to determine the incidence of keratoconjunctivitis sicca (KCS) secondary to trimethoprim-sulfadiazine therapy; to determine if such incidence was related to dose, duration, or both; and to identify any other factors that increased patient risk. The package insert accompanying Tribrissen states that "Dogs can tolerate up to ten times the recommended therapeutic dose without exhibiting ill effects." The results of this study indicated a 15.2% (5/33) incidence of KCS in the population of treated dogs.