When examining the viral agents of the BRD complex, the main diseases to watch out for include bovine viral diarrhea (BVD), infectious bovine rhinotracheitis (IBR), bovine respiratory synctial virus (BRSV) and parainfluenza type 3 (PI3). Because these are often the viral agents producers vaccinate for, confirming a purchased calf’s vaccinations and working with your veterinarian to incorporate a modified-live vaccine on arrival is an important step in managing BRD. But Scruggs cautions there are other viruses and factors that can predispose animals to BRD, so vaccination is not going to be entirely protective by itself.
Once stress factors and viruses attack an animal, dangerous bacteria, like Mycoplasma bovis, Mannheimia haemolytica, Pasteurella multocida and Histophillus somni, are given the perfect opportunity to settle into the lower respiratory tract with little resistance from the animal’s immune system.
Each bacteria common to the BRD complex is a little different, and unfortunately it is virtually impossible to determine which organisms are affecting cattle by visual appraisal alone. Difficult to identify, Mycoplasma bovis is considered one of the most frequent causes of repeat treatments. M. haemolytica is often associated with calves that get sick quickly and is known to be the most responsible for death loss, while P. multocida is commonly associated with treatment failures much like Mycoplasma bovis. H. somni tends to be a problem in northern climates, but has been recognized in all cattle-producing areas, and can look like M. haemolytica.
“It’s important to realize that we often don’t get just one, but a combination of bacteria in a case of BRD,” adds Scruggs.
In addition to minimizing stress factors and vaccinating, the use of on-arrival anti-infectives with extended therapy in higher risk cattle is a key BRD management technique. Not only does this technique allow producers to reduce the number of pulls initially, but it provides more time to pay attention to the management factors that reduce sickness in the first place. Multiple studies show that using tulathromycin on arrival provides significant improvement in morbidity, mortality and first-treatment success rates on stocker and feedlot operations.
“With the use of anti-infectives on arrival, you can pay attention to things that make you money,” encourages Scruggs.
Treating the complex
“There is no typical case of BRD and there is a lot of individual variation in how cattle will respond,” he adds.