The veterinarians at Kansas State Diagnostic Lab indicate that summer pneumonia, also called pasture pneumonia, is a disease mostly seen on pre-weaned calves on pasture late in the summer. Two viruses are usually related to causing this disease including bovine corona virus and bovine respiratory syncytial virus, or BRSV.
The diagnostic lab reports that a Kansas herd experienced the disease early in spring shortly after pasture turnout. This herd consisted of about 200 commercial beef cows that calved in the spring, and at three days of age the calves were all given a respiratory and clostridial vaccine. The herd was then housed in a dry lot until the middle of May and then cows and their calves were turned out on pasture. At that time the calves were about four months of age and were revaccinated with the same vaccine they received earlier. In about three weeks, calves in multiple pastures began to show symptoms of severe respiratory disease with temperatures over 106° Fahrenheit, severe breathing difficulty, and open mouth breathing. Fortunately, the rancher called his local veterinarian who performed necropsies and sent in samples on the calves that died. Results indicated the calves died of severe bronchointerstitial pneumonia and PCR testing was positive for bovine respiratory syncytial virus with secondary bacterial infections. The local vet started the remaining sick calves on appropriate antibiotics and although 60 calves were affected, 17 calves did not survive. So even in well vaccinated herds, respiratory disease outbreaks can occur and the sooner you call your veterinarian and have testing done, the sooner the problem can be diagnosed and treatment can begin.