Back in March 2024, I wrote a post about a systematic review of the efficacy of antibiotics and probiotics and the associated treatment guidelines for acute diarrhea in dogs from the European Network for Optimization of Veterinary Antimicrobial Treatment (ENOVAT). Now, we have an ENOVAT/WSAVA infographic to put all that into a (hopefully) quick reference for veterinarians.

While we’ve historically used antimicrobials like metronidazole by rote to “treat” acute diarrhea in dogs, a lot of dogs were probably getting better despite what we were doing rather than because of it. Antimicrobials are needed in dogs with severe disease, but that’s to target systemic infection in those cases, not necessarily what’s going on in the intestine.

It’s pretty straightforward, as the infographic shows:

• Dogs with mild diarrhea: no antimicrobials needed, just basic supportive care like a GI diet.

• Dogs with moderate diarrhea: fluid therapy first, and if that resolves the systemic signs then no antimicrobials required. If signs persist that might be attributable to sepsis, then it’s considered severe and systemic antimicrobials are warranted.

• Dogs with severe diarrhea and systemic illness: systemic antimicrobials are warranted.

The standard disclaimer is that guidelines are meant to cover most cases, but there can be nuances to individual cases that indicate the need for a different approach. That’s fine, but we still want to try to use an evidence-based approach as much as we can to determine the default treatment.

Of all the guidelines with which I’ve been involved, this one is by far the hardest to get people (including veterinarians and pet owners) to accept, since we are so conditioned to treating diarrhea with antibiotics. We do it because we’re risk averse, because it’s habit, and because we are conditioned to want to do something – even when there’s no evidence that the something is useful. A large percentage of the metronidazole that is used in dogs is psychotherapeutic… for the pet owners and veterinarians, because it makes the people feel better, but not the dog. In fact, those antimicrobials might actually make the dog feel worse.

We’ve made big strides in veterinary antimicrobial treatment guidelines in recent years, and this is one more step in the right direction, but we still have a long way to go.