Antimicrobial-associated diarrhoea in three equine referral practices

Area of Science:

• Veterinary Medicine
• Equine Health
• Pharmacology

Background:

• Antimicrobial-associated diarrhoea (AAD) is a common adverse effect of antimicrobial therapy in horses.
• Few multicentered studies have investigated the prevalence of AAD in equine populations.
• Understanding AAD prevalence is crucial for assessing risks associated with antimicrobial use in horses.

Purpose of the Study:

• To determine the prevalence of AAD in horses treated with antimicrobials for non-diarrhoeic conditions.
• To identify specific antimicrobial agents associated with the development of AAD in horses.
• To explore potential risk factors contributing to AAD in equine patients.

Main Methods:

• Retrospective analysis of a 2009 database from three referral hospitals.
• Inclusion criteria: nonhospitalized horses (weanling or older) treated with antimicrobials for nongastrointestinal conditions and developing diarrhoea.
• Data collected included antimicrobial type, duration of treatment, and results of fecal pathogen testing.

Main Results:

• A total of 5,251 horses received antimicrobials; 32 were diagnosed with probable AAD, yielding a prevalence of 0.6%.
• The mortality rate in horses diagnosed with AAD was 18.8%.
• Commonly implicated antimicrobials included gentamicin/penicillin combinations, enrofloxacin, and doxycycline. *Clostridium difficile* and *Salmonella* were identified in some cases.

Conclusions:

• The overall prevalence of AAD in horses is low.
• Any antimicrobial class used in equine practice can potentially cause AAD.
• Opportunistic enteropathogens and other risk factors may contribute to AAD development, emphasizing the need for judicious antimicrobial stewardship.