In bovine practice, smarter antimicrobial selection starts by asking better questions. Antimicrobial stewardship isn’t necessarily about using fewer drugs, but using the right drugs for the situation. Dr. Corale Dorn, owner of Dells Veterinary Services in South Dakota, suggests asking the following nine questions before reaching for a bottle.
1. What Pathogens Are We Treating?
“You’ve got to get the diagnosis right before you pick what antibiotic you’re going to use,” Dorn says.
Antimicrobial selection in cattle must begin with pathogen clarity.
Is this truly bacterial disease? And if so, what are the most likely pathogens? A navel infection differs from respiratory disease just as uterine pathogens differ from central nervous system pathogens.
“We’re super lucky that people will bring the sick animals to us … so we have the opportunity to do a very thorough physical exam,” Dorn says. “We want to get that diagnosis right, or at least a good list of differentials, and we’re thinking about some of those comorbidities.”
Before selecting an antimicrobial, narrow your differentials and identify the organisms you are most likely targeting. Stewardship starts here.
2. Is There Something Labeled We Can Use?
Start with labeled products whenever possible.
Is there an antimicrobial approved for this disease in this species? Labeled use strengthens regulatory compliance and simplifies withdrawal considerations. Extra-label drug use may be necessary, but it should follow a clear rationale, be well documented and be founded on a valid veterinarian-client-patient relationship.
3. Is There Any Medication We Cannot Use?
Antimicrobial selection is as much about exclusion as it is about selection.
Are there legal restrictions? Are certain drugs prohibited in food animals? Do extra-label drug use regulations eliminate certain options?
Removing inappropriate options early protects both the patient and practitioner.
4. Can We Reach the Pathogen Where It’s Living With This Drug?
Pharmacokinetics and tissue penetration should drive decisions.
“There’s lots of things out there that are labeled for Histophilus somni in cattle to treat it. However, if it’s in the brain and it’s causing TEM, is that drug going to be able to penetrate through the meninges?” Dorn asks.
Drug labels and spectrum charts are helpful, but drug distribution determines success. Lung tissue, uterus and central nervous system each present different barriers.
Dorn explains often the question posed is whether bacteriostatic or bactericidal antibacterials are better. In the past, students were taught bactericidal was best, but recent work suggests that it doesn’t really make a difference.
“Can that drug get to that location is more important,” Dorn says. “It doesn’t really make a difference whether it’s static or cidal as long as we’re giving support to the animal.”
5. Can We Even Get That Product Right Now?
Dorn has an all too familiar question she has to ask: “Is it even on the shelf this week?”
Ideal protocols mean little if the drug is unavailable.
“The supply chain business is just infuriating. You get it down to your favorite protocols, and then that’s not available anymore,” Dorn says.
Drug shortages and supply variability have become part of production medicine. Understanding drug classes and alternatives allows flexibility when inventory shifts.
6. What Are the Milk and Meat Withdrawals?
Withdrawal times are central to antimicrobial use in cattle.
How long are milk and meat withdrawals? Does this animal’s stage of production make those intervals critical? Is she close to market? Is she a high-producing dairy cow?
Withdrawal considerations affect economic decisions and regulatory compliance.
7. How Many Treatments and How Easy Is the Treatment?
“You’re thinking about how many treatments this is going to take and how easy it is to give the treatments in this particular case,” Dorn says, acknowledging each operation is different. Daily restraint in a well-designed dairy parlor differs dramatically from catching pasture cows multiple times.
Communicating the impact of the individual operation with your client is also important.
“It never fails,” Dorn says. “You give a treatment, and they say, ‘Oh, that’s not what you gave my neighbor’s cow last week.’”
Treatment protocols must fit the production system, not just the pathogen.
8. How Much Does It Cost?
Drug choice influences not only treatment success but also labor costs, compliance and client perception.
“You will build relationships with your clients by kind of walking through the thought process and letting them decide they’d rather spend more money and not have to treat her [again] versus just complain that you always pick the most expensive antibiotic when you get there,” Dorn explains.
Transparency strengthens trust and structured reasoning builds credibility.
9. How Does This Fit Antimicrobial Stewardship?
Every antimicrobial choice contributes to the broader stewardship landscape.
“Make sure that we protect those antibiotics that we want to be able to use,” Dorn says, praising the work AABP has done to ensure antimicrobial availability. “In order for all of us to be able to do this for generations to come, you have to think about this.”
Responsible antibiotic use in cattle requires:
- Confirming bacterial disease
- Targeting pathogens where they reside
- Choosing appropriate, reachable drugs
- Considering withdrawals
- Evaluating practicality and cost
- Preventing recurrence through management
Veterinary antimicrobial stewardship protects drug efficacy for future herds and future generations.
The Bottom Line
Antimicrobial selection in cattle is not about memorizing a gold standard drug. It is about systematically answering the practical questions.
“It’s not one gold standard,” Dorn says. “It is a continuum and it’s going to be tailored to the situation that’s in front of you. You need to take a look at the whole picture from the client and then come up with a best agreed-upon treatment plan.”
Taking a pause to consider the whole picture could be the most important step in making sound antimicrobial decisions.
