Assessment of respiratory diseases and therapeutic intervention by the forced oscillation technique in feedlot cattle.

The forced oscillation technique was used to study pulmonary function in bulls during naturally acquired pulmonary-gastrointestinal disease complex known as shipping fever and as it was treated with two different antibiotics. Fifteen double-muscled bulls of the Belgian White and Blue breed were investigated. Clinical, serological and pulmonary function values were recorded during and after naturally occurring respiratory disease. Total respiratory resistance (Rrs) and reactance (Xrs) were measured by the forced oscillation technique. The antibiotic ceftiofur (group A, n = 10) and oxytetracycline (group B, n = 5) were given over three days. A large increase of Rrs at low frequencies with a marked negative frequency dependence, an increase of the resonant frequency, and a decrease of Xrs were recorded in the initial stage of the disease. The parameters returned to normal values seven days later. Clinical evidence of recovery was more marked in group A than in group B. These results show that moderate shipping fever induces acute small and large airway obstruction which responds to appropriate antibiotic therapy.