Bovine Respiratory Disease (BRD)

- Introduction

Bovine Respiratory Disease is one of the most common respiratory diseases in cattle. It is the most common cause of illness and death in feedlot cattle. It can be seen in extensively managed beef herds, particularly calves and weaners. The most susceptible animals are beef calves around the time of weaning, between 5 and 8 months of age, and dairy calves younger than 3 months of age. The infection is usually a sum of three codependent factors including stress, an underlying viral infection, and bacterial infection (stress + virus + bacteria). Most BRD cases are of endogenous source caused by the commensal bacteria in the upper respiratory tract at the throat region. The viruses are also carried by the cattle, the most common one of these (IBR) which is a herpesvirus. The disease is usually triggered during or following a stressful period by a viral infection and a subsequent infection of the airways with opportunistic bacteria. This combination of stress factors and infectious agents makes feedlot cattle especially vulnerable. Pasteurella multocida (P. multocida) and Mannheimia haemolytica (M. haemolytica) are the most two common bacterial causes. The initial signs of BRD may start as watery nasal discharges and a soft, tentative cough. As the infection gets worse, a loud, harsh cough and cloudy nasal discharges appear. Then the calf becomes dull, depressed, stand alone, taking short and shallow breaths and may have their neck outstretched to aid breathing. Diagnosis of BRD Complex is made by clinical signs, case history, physical examination. laboratory testing and ultrasonographic examination. Borad spectrum antibiotics or sensitivity based abtibiotic can be used for treatment along with anti-inflammatory, antipyretics and supportive therapy. Prevention of BRD should focus on decreasing the stressors, make sure that calves got the colostrum, and correct the management and environmental factors.