A comparision of the efficacy of florfenicol and oxytetracycline in the treatment of naturally occurring infectious bovine keratoconjunctivitis

Introduction Infectious bovine keratoconjunctivitis (IBK) is caused by a Gram-negative bacterium, Moraxella bovis. It is characterised by acute contagious ophthalmia and it spreads rapidly among cattle in a herd. M. bovis is generally present on the mucous membranes of healthy animals and is considered to be an opportunistic pathogen (Quinn et al., 1994; Gyles and Thoen, 1993). The bacterium is transferred to susceptible animals by direct contact with contaminated material, by insects and by particles in the air (Brown et al., 1998). Unfortunately, other than fly control, little can be done to halt the spread of the disease, and currently available vaccines have limited efficacy (Smith et al., 1990). Thus, treatment of individual animals is often necessary to reduce economical losses caused by IBK. Several studies on IBK have shown that florfenicol, a derivative of chloramphenicol, can be used successfully in the treatment of cattle (Cosgrove et al., 1998; Varma et al., 1998; Angelos et al., 2000). When the drug was injected intramuscularly (im) and subcutaneously (sc), its effectiveness was 98% and 93%, respectively (Cosgrove et al., 1998a; Angelos et al., 2000). Oxytetracycline preparations have been widely used in animals for the treatment of IBK (George et al., 1988; Eastman et al., 1998) and other bacterial infections (Johnson et al., 1998; Ayling et al., 2000). However, studies have indicated that several bacterial species may have developed resistance against oxytetracycline (Erdeger and Aydın, 1991; Eastman et al., 1998). A comparision of the efficacy of florfenicol and oxytetracycline in the treatment of naturally occurring infectious bovine keratoconjunctivitis