by: Kelley Steury, DVM, MPH, DACVPM
Thompson Bishop Sparks State Diagnostic Lab, Auburn

Bovine pneumonia is one of the most common causes of death in cattle that we see here at the diagnostic laboratory. When animals are submitted to us with a history of losing multiple animals on the farm, pneumonia is often to blame. Pneumonia in cattle, also called Bovine Respiratory Disease (BRD) complex, is caused by an assortment of factors relating to environment, management, and specific infectious agents including viruses and bacteria. Bovine pneumonia causes death losses, certainly, but can also cause losses to the producer when animals are ill but do not die of their disease; these losses might include decreased weight gain, expensive treatments, and extra labor.

An animal with pneumonia usually has nasal discharge and a fever, is depressed, and may be reluctant to move around or eat. It might be coughing or could have rapid, labored breathing. Or, you may not see any clinical signs at all, and might simply have animals who you discover already dead. If you're able to check on your cattle at least once a day, you might be able to see signs of this condition in time to get it treated by a veterinarian, and hopefully decrease your losses.

Let's discuss some management and environmental factors that can predispose to pneumonia, because here is where you can really make a difference in protecting your animals' health. Cattle are stressed by crowding, being shipped or moved to new locations, weaning, castration or dehorning, inadequate nutrition (hunger), inadequate water (thirst), excessive heat or cold, adverse weather conditions, separating animals from their previous groups, and handling for any reason. Being aware of stressful periods should help you be more vigilant to look for any signs of illness.

Have you heard the term "biosecurity"? Biosecurity refers to a collection of management practices meant to prevent the introduction of disease on to your farm. One of the most common triggers for a pneumonia outbreak on a farm is recent addition of new animals to the herd without quarantine. So, if you go to the sale and purchase new stock, it is recommended that you quarantine those animals for an adequate period (such as 30 days) without any contact (personnel or equipment) between the new and the established animals on the farm to observe for signs of disease. Other aspects of biosecurity include testing newly acquired animals for disease, not using borrowed or leased bulls, limiting visitors to your operation and preventing contact between your animals and certain wildlife or exotic species that may carry disease (such as deer). If you would like to read more about biosecurity, the United States Department of Agriculture-Animal Plant Inspection Service (USDA-APHIS) has information about biosecurity in cattle. See website: www. aphis.usda.gov/animal_health/nahms/beefcowcalf/downloads/ beef 0708/Beef0708_is_Biosecurity.pdf

What infectious agents cause pneumonia in cattle? Both bacteria and viruses can cause pneumonia or can suppress the normal immune function to allow other infectious agents to set up infection. Some of these infectious agents work together. Viruses that can initiate respiratory disease in cattle include herpes virus (Infectious Bovine Rhinotracheitis), BVD virus (Bovine Viral Diarrhea Virus), PI3 (parainfluenza), and BRSV (Bovine Respiratory Syncytial Virus). Cattle who have been well-vaccinated for these respiratory viruses are much less likely to die of pneumonia than cattle who have not. Bacterial causes of pneumonia include Mannheimia haemolytica, Pasteurella multocida, and occasionally Haemophilus somnus. Mycoplasma is another bacteria that tends to suppress the immune system, and thus facilitates infection with other bacteria to worsen and complicate the pneumonia. Work with your veterinarian to ensure that your cattle are fully vaccinated and boostered at the appropriate intervals to decrease their risk of pneumonia.

As a producer there are actions you can take to decrease the chance of your cattle developing this severe and potentially life-threatening condition. Make sure your animals have good nutrition. Minimize the stress of handling and shipping as much as possible. Be sure that you buy cattle from reputable sources with known health records, and quarantine those new animals on arrival. Ensure that calves nurse colostrums from their dams within six to eight hours of birth. Observe all of your cattle at least once if not more often per day so that illness can be noted and those ill animals treated. Vaccinate and booster your cattle as recommended by your veterinarian. Taking these key steps are vital to a healthy cattle operation.

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