Veterinarians are building treatment plans for livestock that keep in mind antibiotic resistance, in part because of the vast number of antibiotics that are also used for humans, according to an announcement from Kansas State University.
“Antibiotic resistance is real,” said Mike Apley, Kansas State professor of production medicine and clinical pharmacology in the College of Veterinary Medicine. Apley spoke with fellow veterinarian Brad White on a recent Beef Cattle Institute podcast.
“The last time a new family of antibiotics was introduced in food animals was in 1978,” Apley said. “We’ve had new members of those families since then, but we are probably not going to get more.”
Apley has seen some pathogen resistance to those antibiotics, especially with respiratory diseases for which it is common practice to give a long-acting treatment.
“You expect 70-80% of the (animals) you treat to respond and not need further intervention, but that is allowing them a five- to seven-day interval to respond to the initial treatment,” Apley said. He also said respiratory disease in calves may result in 5-10% death loss in those previously treated.
He advised producers to evaluate herd sickness; if a large percentage of the calves are ill, then it is time to reassess the treatment protocol. Apley said there are two main factors he considers when he is consulted regarding a disease outbreak.
“First is the treatment success rate, and the second is the case fatality rate,” Apley said, noting that producers should keep good records of treatments they give their animals to more clearly understand what is happening.
“It is easy to want to switch drugs when I feel that things aren’t going well; however, if I start changing drugs frequently, that will impact my ability to accurately evaluate those records,” White said.
“When things are at their worst, by definition, they are going to get better,” Apley added. "When you switch things up in the middle, you tend to give credit to what you switched to."
The veterinarians stressed that using treatments appropriately is best for both livestock and people.
“For antibiotics that are important for human use, we are under pressure to limit their use in animals,” White said. “The challenge is that the drugs used for livestock are also members of the [antibiotic] families used for humans.”
Apley estimated that about 10 drugs used to treat livestock are not used by people. He said one class of antibiotics, ionophores, is primarily livestock focused.
White advised producers: “When you are using antibiotics on the farm, you want to make sure you are using them appropriately, and one of the best ways to do that is to have a treatment protocol in place. You need to understand what you are treating and why you are treating it.”