Bovine respiratory disease (BRD) accounts for the highest percentage of deaths in cattle and calves outside of predators. Antibiotics are an important tool to promote well-being in cattle, especially when it comes to BRD. However, there are a lot of factors to take into consideration when making treatment decisions, including how to mitigate the risk of antibiotic resistance and ensure the longevity of treatment options.
What makes BRD so challenging is it’s a syndrome with several infectious agents associated with it. Infectious bovine rhinotracheitis (IBR), bovine viral disease (BVD), and bovine respiratory syncytial virus (BRSV), are some of the cattle diseases that we have vaccines to treat beef and dairy calves.
“The goal is to set them up with some prior immunity before they get into the feed yard,” said Dr. Ron Tessman, DVM, principle research scientist at Elanco. “We also have several bacterial pathogens associated with BRD, the most important of which is Mannheimia haemolytica. There are several other pathogens, including mycoplasma, which has become a bigger issue over the last 20 years.”
Overall, there are a large number of pathogens associated with BRD. The disease will often manifest itself at different stages of infection, depending on which infectious agent triggered it and the inoculant. One thing that can help pinpoint it is when animals are under some type of stress. That’s when BRD, sometimes called “shipping fever,” will show up in herd animals.
“They could be getting comingled into groups of animals that don’t know one another,” he said, “so they’re mingling and trying to figure out their hierarchy. They also are stressed when they’re shipped from their home area on a long truck ride, are introduced to a new feed, and possibly undergo some processing work when they arrive. That combined stress can lower their immune response.”
This opens the door for one of the infectious agents, such as IBR, an infectious agent that will manifest quickly in a herd. Depending upon the specific infection, farmers can get a lot of variations in what signs of infection they see and how quickly they’ll see them. One of the easiest-to-spot signs is depression in animals, which will typically reveal itself when they have their heads down and ears lowered.
“Quite often, they’ll have a cough and a runny nose like a human would with a respiratory infection,” Tessman said. “They won’t eat, tend to stay away from the other animals, and will likely have a fever. Those are the predominant signs of infection.
“We in the cattle industry liken it to kids going off to school for the first time,” he continued. “They’re coming from home as young people with immune systems that aren’t fully developed, and they come together to trade viruses with each other.”
The veterinarian says it’s because of those factors that Elanco stresses “management over medicine.” It starts with doing the right things all the way back to the cow even before she gives birth. The hallmark of the best management practices he recommends is a good vaccination program for the most common viral components that cause BRD.
“Yearly vaccinations will make sure the cows are healthy and can produce some antibodies to those pathogens in that colostrum the calves drink during the first 24 hours of their life,” he said. “That gives the young animals ‘passive immunity,’ which the calves can’t develop in utero because they aren’t getting a lot of the immunoglobulins that would strengthen their immune systems.”
While it’s vital to keep cows at optimum health, best management practices for calves include keeping them as free from stress as possible. As they continue to grow and develop their immune system, Tessman said that’s the point at which you can put some vaccines into the calves to help fight BRD and other pathogens. It’s also a good idea to try to transition them to a more concentrated diet if the opportunity arises.
“Before we ship those animals to a feedlot or a backgrounder or a stocker, we want to prepare them as best we can,” Tessman said. “Get some vaccines in those animals when they aren’t stressed, so their response is as optimal as it can be. Unfortunately, sometimes things just happen, and farmers can’t always get those things taken care of right away.
“Plus, we’re talking about biology here, so not every animal is going to respond to the vaccines and other things we try to do,” he added. “While it may not happen every year, even the best producers will have animals that come down with a respiratory disease.”
Tessman says when you compare a cow’s lungs to other mammals, they aren’t as anatomically equipped to respond to bacterial and viral pathogens. That’s why producers have to do everything they can to maximize an animal’s response to them, knowing that those lungs aren’t the best equipped to fight respiratory disease.
While it’s uncommon for adult cows to contract “full-blown BRD,” it’s not out of the question. Throughout his veterinary career, Tessman has seen disease outbreaks in herds through fence line contact with other herds, or by bringing in additional animals who may not have had all of the appropriate vaccines to fight BRD.
“We see the most BRD outbreaks in calves anywhere between three and eight months old,” Tessman said. “It’s typically when they’re leaving the cowherd and entering their next stage of life. If we haven’t set them up for success, that’s when problems arise.”
When BRD does pop up in your herd, Elanco has four antibiotic choices to help you manage the outbreak. He said it’s important to stress that there’s “not just one solution,” which is why it’s important to have multiple solutions available. The right solution depends on several factors, such as what the management system is like and what the animals were treated with in the past.
“No matter what solution or solutions a producer chooses, what we strive for is not to overuse antibiotics,” he said. “We know what the potential adverse outcomes of that could be. I want to use the appropriate antibiotic at the appropriate time and for the correct duration. That’s one big thing we are continually trying to define.”