If I asked 100 random people on the street “should we be giving antibiotics to healthy animals?” I’m pretty sure most or all of them would say “no.“

That makes sense in a lot of ways. We should save antimicrobials to treat sick individuals (especially people), and we shouldn’t use antimicrobials in healthy individuals… except when we should.

If I asked to the same 100 people “Should your dog get an antibiotic if it eats something it shouldn’t have, and then needs to have surgery to open up the intestines to remove the object?” I’m pretty sure most would say “yes!” – even though that dog doesn’t have an infection. That’s prophylactic use of an antimicrobial.

Like most things in the antimicrobial resistance (AMR) space, this issue of prophylaxis is complicated and messy. Too often, the sound bites we hear about approaches to antimicrobial use (AMU) in animals miss the nuances and complexities that play a huge roll in the necessary discussions. 

  • We don’t want to overuse antimicrobials.
  • We don’t want to use antimicrobials unnecessarily.
  • We don’t want to use antimicrobials to compensate for poor animal management or lack of veterinary care.
  • But, there are situations where antimicrobial prophylaxis makes sense and logical prophylaxis can improve animal health and animal welfare, and reduce the need for therapeutic use of antimicrobials (that might be higher tier drugs) with limited risk.

There’s always some risk with the use of antimicrobials in any animal or person, but part of optimizing antimicrobial stewardship (AMS) is using them when we should, and avoiding them when we shouldn’t. Use antimicrobials as little as possible, but use enough.

Because we keep running into the same misconceptions and misunderstandings about AMR and AMU at various levels (including high level international discussions) we teamed up with the World Organization for Animal Health (WOAH) and the quadripartite‘s AMR Multi-stakeholder Partnership Platform to write a primer on antimicrobial prophylaxis in animals. The document discusses when antimicrobial use is bad, when it’s clearly indicated, and a few levels in between.

Prophylaxis can include scenarios such as:

  • Routine administration of antimicrobials to groups of animals in the absence of evidence of need, largely because of historical practices. 
  • Routine administration of antimicrobials for a prolonged period of time to a group of animals because of a high endemic rate of a specific disease in the group.
  • Routine administration of antimicrobials to most or all animals at a specific stage in life or production to reduce a specific disease or syndrome (e.g. tetracycline treatment of pigs at the time of weaning to prevent post-weaning diarrhea, administration of intramammary antimicrobials to dairy cattle at the end of lactation to prevent mastitis, tetracycline with ITM vaccination for prevention of East Coast fever).
  • Targeted administration of antimicrobials to a group of animals in response to a specific, defined disease threat that is known to be mitigated by antimicrobial prophylaxis.
  • Administration of antimicrobials to a specific animal at a specific and well-defined high-risk time (e.g. peri-operative antimicrobial prophylaxis for prevention of surgical site infection).

Some of these are good uses of prphylaxis, some are bad, and some are situational. But it shows the wide range of possible prophylaxis scenarios. We need to make sure we use antimicrobials when they are needed, but not prophylaxis as an excuse to overuse them or try to avoid scrutiny. It can be challenging to have discussions about why we need prophylaxis when some people think we’re just being apologists for the agriculture industry.

Do we need to improve antimicrobial prophylaxis?  Yes, especially in agriculture.

Can we massively reduce antimicrobial prophylaxis without negative impacts on animals? Yes, if we do it right, and if we do the other things we should be doing to prevent infections and optimize animal health.

Do we need to use some antimicrobial prophylaxis in animals? Yes, but we need to find that “use as little as possible but use enough” sweet spot. That’s not easy, but it’s clear we can reduce what we currently use a lot.

We need to have informed discussions about prophylaxis, not dogmatic debates with “all prophylaxis is bad” as an entrenched starting point.