Acute pneumonia most commonly occurs during the 1st week after arrival in the feedyard. This disease, known as shipping fever or the bovine respiratory disease complex, has been investigated for decades. Respiratory disease viruses and stress are major components, since PP rarely occur in the healthy, unstressed calf. Much research has been focused on PH itself and on its role in the disease complex during the last 20 years. The disease still occurs, usually within a predictable time frame.
Morbidity can be high, but the mortality is kept low by timely antibiotic therapy.
Reduced rate of gain, vaccination and treatment expenses, and death losses constitute a major financial loss to the US beef cattle industry. This general description of the disease and its impact remain true today. The marketing process is still basically the same, and is incompatible with effective vaccination schedules. New antibiotics are used, as more PH isolates become resistant to those previously used. The objective of this review is to briefly discuss newer areas of research on PH, with an emphasis on that reported in the last 5 years, and its significance.