Shipping fever

Bovine respiratory disease (BRD) is the most common and costly disease affecting beef cattle in the world. It is a complex, bacterial infection that causes pneumonia in calves which can be fatal. The infection is usually a sum of three codependent factors: stress, an underlying viral infection, and a new bacterial infection. The diagnosis of the disease is complex since there are multiple possible causes. Bovine respiratory disease (BRD) is the most common and costly disease affecting beef cattle in the world. It is a complex, bacterial infection that causes pneumonia in calves which can be fatal. The infection is usually a sum of three codependent factors: stress, an underlying viral infection, and a new bacterial infection. The diagnosis of the disease is complex since there are multiple possible causes. The disease manifests itself most often in calves within four weeks of weaning, when calves are sorted and often sold to different farms; a common nickname for BRD is 'shipping fever.' It is not known whether the stress itself, co-mingling, or travel conditions are at most to blame, and while studies have identified general stressing factors like transport and cold weather conditions, there is still no conclusive evidence on more specific factors (e.g. distance, transport mode, temperature, or temperature volatility). BRD is a 'multi-factorial syndrome' that is dependent on a number of different causes. The pathologic condition commonly arises where the causative organism becomes established by secondary infection, following a primary bacterial or viral infection, which may occur after stress, e.g. from handling or transport. Usually all three of these factors must be present in order to cause BRD. Viral agents are often present in the herd for an extended time, with almost no symptoms, and only cause severe complications with a bacterial infection. The bacterial agents most commonly linked with BRD are Mannheimia haemolytica, Pasteurella multocida, Histophilus somni, and Mycoplasma bovis. M. haemolytica serovar A1 is known as a particularly common bacterial cause of the disease. Viral agents include Bovine viral diarrhea (BVD), Infectious Bovine Rhinotracheitis (IBR), Bovine respiratory syncytial virus (BRSV), and Parainfluenza type-3 virus (PI-3). BRD often develops within 4 weeks of cattle transport. The biggest sign of the pneumonia that BRD causes is depression, shown as droopy ears, dull eyes, and social isolation. Additionally, most cows will have a fever above 104 °F (40 °C). Other symptoms include coughing, decreased appetite, and breathing difficulty.