Control of inflammation in experimental bovine pneumonic pasteurellosis

Abstract

An experimental model of bovine pneumonic pasteurellosis was used to compare the effects on lung mechanical, gas-exchange, biochemical and cellular parameters before and after a nonsteroidal and a steroidal anti-inflammatory drug. Eight Friesian calves were inoculated with Pasteurella haemolytica. After randomisation, 4 calves were treated with a nonsteroidal drug (ketoprofen) and 4 calves with a short-acting dexamethasone solution, all in combination with antibiotics for three days. The calves were inoculated a second time, three days after the last treatment. Flow cytometry was used to differentiate blood mononuclear cells and to measure oxidative burst capacity of anti-inflammatory cells in venous blood and in brochoalveolar lavage samples before and after inoculation and treatment. After the first inoculation, all calves had increased respiratory rates, rectal temperatures, increased neutrophil blood count, and a decline of the arterial pressure in oxygen and lung compliance. After treatment, rectal temperature dropped significantly (P < 0.05) and a higher arterial pressure in oxygen was found in both groups. However, there was only in the ketoprofen group a significant reduction of the tachypnea. After the second inoculation, a significant drop of the arterial pressure in oxygen and a significant higher respiratory rate was seen only for the dexamethasone group, while a significant neutrophilia was found only in the ketoprofen group. No important treatment differences of oxidative burst activity were evident using the flow cytometry technique due to the large within treatment group variability. In this model of lung inflammation, there was a significant higher impairment of the lung mechanics and the arterial pressure in oxygen after the second Pasteurella challenge for the dexamethasone group compared to the ketoprofen treated calves.