Pneumonia is the common term for lung infection. In cattle it’s often called shipping fever because it frequently affects calves that have undergone stress of weaning and being shipped to a feedlot.
Stress is a major factor in whether calves get pneumonia—which can appear at any age since most of the bacterial pathogens that cause pneumonia are already present in the calf’s upper respiratory tract. These bacteria only become a problem in the lungs if the calf’s immune defenses are compromised by viral infections or stress, which may enable them to move on down into the lungs.
Stress may be due to inclement weather, extreme changes in temperature, a long truck haul, overcrowding in a dirty environment, etc. Nutritional deficiencies such as lack of an important mineral like copper or selenium may impair the immune system.
Respiratory infection in young calves has been called “summer pneumonia” and the cause is not easy to determine; cases can appear during good conditions when we don’t think of these calves as stressed. In some cases, calves get sick out on summer pasture.
This is an erratic disease, according to Dr. Chris Chase, Department of Veterinary and Biomedical Sciences, South Dakota State University. A producer might see some sick calves one year and no problems the next year. We often don’t know what the difference might be, and sometimes cases are hard to diagnose.
There might be viruses involved, like bovine respiratory syncytial virus (BRSV), or bovine coronavirus. “There are some pathogens that we might find if we are looking for them, but often in a cow-calf operation by the time we examine the sick calf or get a sample to send for testing, it may be too late to find the pathogen,” Chase said.
Two age groups
Calf pneumonia tends to occur in two different age groups–young calves up to a couple months of age and then later when calves are at pasture and close to weaning age. The risk factors for those two groups are generally different. The younger calves may be vulnerable to pneumonia if they didn’t receive adequate colostrum.
Some producers calve their cows in barns and small pens in late winter or very early spring, and these situations may create exposure to more pathogens than if they were out in big pastures. Confinement and contamination can be major risk factors in very young calves.
Older calves, on pasture, may be vulnerable when their passive (temporary) immunity from colostrum diminishes. When producers have problems with pneumonia the veterinarian generally looks at age of the calves, and which risk factors may have been present prior to them getting sick.
Risks vary from farm to farm. One risk might be gathering pairs for AI synchronization programs, when calves are stressed while temporarily separated from their mothers and in close confinement with other calves. A year with bad weather, or a hot, dry,…
Read more:: Watch for summer pneumonia in young calves