Pneumonia in beef calves following the stress of weaning or shipping has been very well-documented. However, not as much is known about the risk factors that contribute to pneumonia in calves on pasture prior to weaning.

Pneumonia in young beef calves on pasture can manifest itself in several different ways. The clinical picture may include obvious signs such as increased respiratory rate or cough, but sometimes all that is noticed may be a calf that is lagging behind the rest of the herd, or one with slightly droopy ears. When rectal temperatures of these calves are taken, often fevers of 104-106 F will be apparent.

One favorable aspect of pre-weaning calf pneumonia, at least in herds in this area, is that it seems that a fairly low percentage of calves in a herd usually are affected during a particular season. In addition, when these calves are treated, the clinical signs generally respond fairly well to antibiotics, without a high mortality rate. However, calves with respiratory illness typically do not gain weight as well as non-affected calves, and restraint and treatment of calves on pasture is often difficult.

Since identification of its risk factors is still the subject of research, summer pneumonia in beef calves is a syndrome for which there are no clear preventive methods. Use of viral (IBR-BVD-BRSV-PI3) and sometimes bacterial (Mannheimia haemolytica and Histophilus somni) vaccines are commonly recommended at turnout or branding for herds experiencing previous outbreaks. However, vaccines do not universally prevent pneumonia cases from occurring in every herd.

Paying attention to exposure to other animals that may be shedding large amounts of respiratory viruses and bacteria makes sense. One recent university research report indicated higher incidence rates of pre-weaned calf pneumonia in herds in which new cow-calf pairs were brought into the herd during the season. Cattle producers should also take steps to prevent contact between baby calves and older, feedlot-aged cattle in their operation. Even though in both cases, new cattle rarely show signs of illness themselves, they pose a higher risk of shedding organisms to which a young calf may be more vulnerable.

Stresses related to weather and separation of calves from their mothers should also be examined. While weather stress due to heat or dust may be difficult to avoid on summer pasture, prolonged separation events (such as during artificial insemination or synchronization) should be minimized to reduce the stress and therefore disease vulnerability on the calves.

Much remains to be learned about how we can best prevent these instances of calf pneumonia on pasture. This summer, SDSU researchers are participating in a multi-state examination of risk factors that contribute to this syndrome. Ask your veterinarian about what steps you can take to help minimize and promptly treat this condition in your calves.

Source: Russ Daly, South Dakota State, State University Extension.

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