Pharmacodynamic properties – tissue penetration, intracellular effect
Will antibiotics make a difference? In adult cattle, antibiotics may improve recovery and lessen the severity of the disease but will likely extend the duration of shedding. Calves and young stock are expecially prone to becoming bacteremic, but subtherapeutic use of antibiotics in the milk replacer may actually make the disease worse.
Disseminated, invasive or systemic disease (how do you tell?)
Severe clinical signs of endotoxemia : fever, tachycardia, tachypnea, scleral injection, weakness, ruminal stasis, leukopenia (early), and leukocytosis (later), frequently with a left shift
Death in some animals
Pneumonia, polyarthritis Post mortem findings are not restricted to dilation, edema and hemorrhage of the bowel and mesenteric lymph node enlargement. There may be enlargement of the spleen, renal infarcts and gallbladder inflammation. Ecchymotic hemorrhages throughout the carcass and pneumonia may also be present
Antibiotics are not likely to affect the carrier state.