Vaccinating calves may or may not prevent outbreaks of summer pneumonia. “Some producers do a very good job of vaccinating their herds, and still have problems,” says Russ Daly, DVM, and Extension veterinarian of South Dakota State University.
“And there are some herds without vaccination programs that get by with very few problems. Vaccination is not a cure-all that works for every producer. They should talk with their veterinarians about possibly using certain vaccines before certain stresses or before the time they’d expect outbreaks. In some situations, vaccines might be worth considering,” he says.
Some producers have started vaccinating calves at turn-out and think it helps depending on the age of calves at that time, and the products used. “Success may depend on whether calves are old enough that their immune systems respond to the vaccination, since maternal antibodies from colostrum may interfere,” says Dr. Amelia Woolums, professor of large animal medicine at the University of Georgia.
“There is research that supports the thinking that calves 60-90 days of age can respond to vaccination. In some instances they do, and sometimes they don’t, depending on different variables,” says Woolums.
Ages of calves at branding varies, since on any given ranch they are generally branded and vaccinated at one point in time—doing all the calves born that season. The oldest might be 2 to 3 months old and the youngest might only be a week old.
“Any calf that’s only a week old is not likely to respond adequately. A dairy calf that got no colostrum can respond to vaccine at a week of age, but a beef calf that had really good colostrum, which is what you want, will not reliably respond to vaccination,” she says.
So it depends on the proportion of the herd that is 1 to 2 weeks old, versus how many are 2 to 3 months old. “If the proportion of really young calves is small, it may not be a problem. But if that proportion is large and producers try to vaccinate at that age, it is likely to be a problem,” Woolums explains. We need more research on the relationship between the age range in a group of calves and the ability of those calves to respond to vaccination.
“There are intranasal vaccines for certain viruses, and bacterial vaccines for Mannheimia and Pasteurella,” says Daly. With respiratory diseases in general, viruses can be a risk factor, though not the sole cause.
“When we see pneumonia cases in the diagnostic lab, the pre-weaning cases are much the same pathogens seen in post-weaning pneumonia in calves. It’s often Mannheimia, Histophilus, or Mycoplasma. It’s harder to create effective vaccines that work against those bacterial pathogens. Vaccines are a tool that should be considered, but may not be the silver bullet we’d like,” says Daly.
When calves get sick out on pasture or range it’s not always easy to access them for treatment, or even to monitor enough to know when one gets sick.
“The good news is that when the calves with signs of pre-weaning pneumonia get treated, they generally respond fairly well. I think this is partly because this is probably their first bout with pneumonia in their young lives and they don’t have any residual inflammation or damage in the lungs that hampers effectiveness of antibiotics. They tend to recover faster than an older calf that might have had respiratory problems earlier. There are reports of much better success with antibiotic treatments for pre-weaning-age calves than for some of the post-weaning cases,” he says.
It helps with diagnosis if producers can get samples (nasal swabs) from calves in an outbreak. “A diagnostic lab might be able to help the producer and veterinarian figure out an informed vaccine program, though it might not be much help for individual calves in this go-round. In some cases, it helps to know what pathogens you are dealing with, especially if it’s consistent among a bunch of calves,” says Daly.
Some ranchers have problems in June-July, while others have sickness in very young calves, soon after birth. Some have pneumonia in older calves, in the month before weaning.
“If it happens close to weaning, that calf might not be able to be sold with the rest of the group. There’s also the issue of long-term damage. Sometimes there is scarring and permanent damage in the lungs and those calves don’t do as well later,” says Daly. It would be beneficial to find a way to prevent these problems. — Heather Smith Thomas, WLJ correspondent
