Bovine respiratory syncytial virus infections in young dairy cattle: clinical and haematological findings.

Clinical signs and haematological findings during the acute and convalescent phases of an infection with bovine respiratory syncytial virus (RSV) were studied under field conditions. The study was carried out in 139 cattle less than 16 months of age in 16 herds with serologically proven bovine RSV infections. Blood was collected for serological and haematological examination. Repeated clinical examinations were carried out until 35 days after appearance of disease. Signs of general disease such as reduced appetite and a body temperature of 40 degrees C or higher lasted less than three days in most cases. Signs of upper respiratory disease, such as coughing, nasal discharge and conjunctivitis were predominant and persisted in 10 to 30 per cent of the animals till the end of the observation period. Signs of lower respiratory disease such as abdominal breathing, bronchial and bronchovesicular sounds on auscultation and a high respiration rate were valuable in diagnosing the disease. These symptoms were present in about 50 per cent of the animals in the early stages of the disease. They lasted for about six days and disappeared in most animals after about 10 days. On haematological examination statistically significant blood changes were observed. A rise in zinc and iron between day 0 and day 10 and a reduction in copper content between day 10 and day 21 were found.