Oral and Poster Abstracts

(Mb) as co-infecting agent is becoming increasingly important. In spite
of this, the possible involvement of Mb is mostly overlooked whilst
choosing the appropriate antimicrobial treatment of BRD-affected
cattle. This trial, applying short-duration treatments, compared
compounds (florfenicol [FFC], cefquinome [CFQ]) that are specifically
directed against Mh, with enrofloxacin (ENR) that targets both Mh and
Mb. Following Mb and subsequent Mh challenge, performed 4 days
apart, groups of young calves (n=10/group) were treated 3 h later with
ENR (Baytril Max 10%, 7.5 mg/kg, one SC injection), FFC (Nuflor
30%, 20 mg/kg, 2 IM injections 48 h apart) or CFQ (Cobactan LA
7.5%, 2.5 mg/kg, 2 SC injections 48 h apart). All treated calves
survived the study but 2/10 untreated control calves died on day (d) 5
after Mh challenge. Whereas the surviving untreated controls continued
to have fever or high body temperature until the end of the study (d7
after Mh challenge), treatment with ENR and FFC controlled fever
within 15 h. It took 72 h to bring down body temperature to baseline
level in calves treated with CFQ. None of the calves treated with ENR,
FFC or CFQ showed respiratory disease signs or morbidity compared
with 4 control calves in which such symptoms persisted until the study
end. At necropsy pneumonia lesions were seen in all control calves and
in 2/10, 4/10 and 8/10 calves treated with ENR, FFC and CFQ, resp.
The median pulmonary lesion scores (scale 0-4) were 1.56, 0, 0, and
0.44 in untreated, ENR, FFC and CFQ groups, resp. Mean Mh counts
in lung tissue of ENR and FFC treated calves were very low (