For this blog, I focus my writing on companion animal issues, but our group does much more than that, and a recent study of ours is worth a post here as well.

Antimicrobial resistance (AMR) is a huge issue globally. It’s a classic One Health problem with important human, animal and environment aspects, and it’s getting a lot more attention now as it’s become a genuine crisis.  We know we need to reduce and improve antimicrobial use in order to stem the tide of AMR. We already know a lot of things we can do to achieve that, and yet we often fail to use those tools.

Why aren’t we doing a better job of using available tools to help reduce antimicrobial use?

There are lots of reasons, but human behaviour is a big one. Despite knowing something is good, people are often resistant to change for any number of reasons, including but not limited to:

  • Culture (we do it that way because we’ve always done it that way)
  • Inertia (change requires effort, an it’s easier to just keep doing the same thing)
  • Lack of motivation to change when the problem isn’t immediately obvious (problems associated with AMR aren’t something most people see every day, and they’re often a “delayed” consequence of poor antimicrobial use, so that decreases motivation to alter practices)
  • Defensive medicine (the desire to treat something with antimicrobials “just in case”)

The last one is an area in which I’m particularly interested.  Sometimes, we (including physicians, veterinarians, farmers, animal owners and others) make treatment decisions based more on protecting ourselves, rather than the individual or group of animals we’re trying to help.

For example, let’s look at management of diarrheic diary calves (which are the focus on the study I mentioned).  Like most neonates, diarrhea is common in dairy calves. Most often it’s mild, but sometimes it can be serious and even fatal. On many farms, most or all diarrheic dairy calves are treated with antibiotics. Yet, we know that most don’t need them.

So why do so many diarrheic calves get treated with antibiotics?

  • Sometimes it’s lack of understanding of when antibiotics will actually be effective.
  • Sometimes it’s simply based on fear of what might happen if they don’t get antibiotics.

If a person’s job is to raise calves on a farm and a calf gets diarrhea, it’s often their decision how to treat the calf.  This is often (and should be) based on a protocol or decision tree developed with the farm veterinarian, but a veterinarian is not always involved in every treatment decision.  But more often than not, that person is going to err on the side of giving antibiotics, versus not.  In our study, we heard from calf caretakers that their thoughts are along the lines of “If the calf gets really sick or dies and it didn’t get antibiotics, it’s my fault.” So, there’s a psychological barrier to not treating. At the same time, the downsides of treating include cost of the drugs (but that’s considered a cost of doing business that no one focuses on), hassle (ditto) and the risk of promoting AMR. However, resistance isn’t as “in your face” on a farm as a dying calf, so instead the focus tends to be on the uncommon, bad outcome (i.e. the calf dying) and resistance it gets written off as an inherent, unavoidable risk that’s someone else’s fault.

So, we’ve heard many say things like “I know I don’t need to use antibiotics in most situations, but it’s my neck that’s on the line if something happens.”  Human behaviour, not biology, is the biggest barrier.

That’s a long winded introduction to a recently published paper that was part of Dr. Diego Gomez’s PhD program, in which we assessed a simple algorithm (below) to help decide whether or not to treat a diarrheic calf with antibiotics.

The algorithm that can be easily applied at the farm level, and it achieves a couple things.

  • It provides more evidence for decision making and education about when antibiotics are are recommended.
  • Probably more importantly, it provides a “cover your butt” component for the people making the treatment decisions on farm. By shifting the decision to an algorithm, concern about blame gets deflected too. Rather than worrying about taking the heat for a bad outcome in a calf, the decision-maker now has some backing (or someone else to blame), making it easier to make the decision they maybe always wanted to make.

So, did using the algorithm actually help decrease antimicrobial use in diarrheic calves?

Yes! There was a significant drop in frequency of antimicrobial treatment on most farms, though not all.  The differences between farms probably relate to how good a farm’s management practices were to begin with, as well as how much they trusted the algorithm (e.g. a farm that was already doing a good job limiting antibiotic use wouldn’t see as much of an improvement).

Overall, across 10 farms, there was a major drop in antibiotic treatment of diarrheic calves.

  • Before the intervention, 85% (1303/1573) of calves were treated.
  • After the intervention, just 18% (310/1698) of calves were treated.

All with a simple algorithm that costs absolutely nothing to use.

AND – very importantly – there was no adverse impact on calf health. Decreasing antibiotic use didn’t’ result in more seriously ill or dead calves, supporting the notion that most diarrheic calves don’t need antibiotic treatment.