CATTLEMASTER 4

IBR, BVD, PI3, and BRSV viruses are commonly associated with respiratory disease and/or reproductive failure in cattle. IBR virus infection is characterized by high temperature, excessive nasal discharge, conjunctivitis and ocular discharge, inflamed nose (`red nose`), increased rate of respiration, coughing, loss of appetite, and depression. Cattle infected during pregnancy may abort.
A characteristic of IBR virus (BHV1) is that it establishes a latent infection in sensory neurons, typically trigeminal ganglia or iliosacral dorsal root ganglia.1 From these sites of latency, it can be reactivated when an infected animal is stressed or injured. Subsequently, the virus is shed and transmitted by contact to other cattle.
BVD virus may be transmitted in nasal secretions, saliva, blood, feces, and/or urine, and by direct contact with contaminated objects; it invades through the nose and mouth and replicates systemically. Infection during pregnancy may result in abortion, fetal resorption, or congenital malformation of the fetus. Moreover, if susceptible cows are infected with noncytopathic BVD virus during the first trimester of pregnancy, their calves may be born persistently infected with the virus. Exposure of those calves to certain virulent cytopathic BVD virus strains may precipitate BVD-mucosal disease. Clinical signs of BVD include loss of appetite, ulcerations in the mouth, profuse salivation, elevated temperature, diarrhea, dehydration, and lameness.
PI3 virus usually localizes in the upper respiratory tract, causing elevated temperature and moderate nasal and ocular discharge. Although clinical signs typically are mild, PI3 infection weakens respiratory tissues. Invasion and replication of other pathogens, particularly Pasteurella spp., is thereby facilitated and may result in pneumonia.
BRSV is the etiologic agent of a specific viral respiratory disease of cattle of all ages, including nursing calves. Infection is characterized by rapid breathing, coughing, loss of appetite, discharge from the nose and eyes, fever, and swelling around the throat and neck. In an acute outbreak, deaths may follow within 48 hours after onset of signs. Clinically, BRSV infection may be indistinguishable from other viral infections associated with the bovine respiratory disease complex. BRSV infection, like PI3, facilitates invasion and replication of other respiratory pathogens. Exacerbation of clinical signs has been documented when concurrent BRSV and BVD or IBR infection exists.