Drug profile

The FDA adverse-event record for Metronidazole

3,306 adverse-event reports submitted to the FDA Center for Veterinary Medicine reference Metronidazole. See the species affected, top reactions, and outcomes below.

3,306
adverse-event reports
18.8%
death-coded share
Dog
most-reported species
929
Diarrhoea - top reaction
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Important: Adverse event reports do not establish that a drug caused or contributed to the event. Consult your veterinarian before making treatment decisions.
3,306
Total Reports
620
Deaths Reported
18.8%
Death Rate

Active Ingredients

Metronidazole

Administration Routes

UnknownOralIntravenousParenteralSubcutaneousTopicalOtherOphthalmic

Species Affected

Dog 2,798
Cat 353
Unknown 138
Horse 8
Human 4
Ferret 2
Chinchilla 1
Donkey 1
Other Reptiles 1

Most Affected Breeds

Retriever - Labrador 351
Domestic Shorthair 216
Unknown 153
Crossbred Canine/dog 151
Retriever - Golden 139
Shepherd Dog - German 129
Terrier - Yorkshire 128
Shih Tzu 90
Chihuahua 82
Boxer (German Boxer) 63

Most Reported Reactions

Diarrhoea 929
Vomiting 880
Lethargy (see also Central nervous system depression in 'Neurological') 570
Other abnormal test result NOS 397
Anorexia 395
Death by euthanasia 361
Elevated alanine aminotransferase (ALT) 333
Weight loss 297
Not eating 286
Bloody diarrhoea 279
Elevated serum alkaline phosphatase (SAP) 251
Death 244

Outcome Breakdown

Ongoing
1,144 (36.0%)
Recovered/Normal
774 (24.4%)
Outcome Unknown
597 (18.8%)
Euthanized
361 (11.4%)
Died
264 (8.3%)
Recovered with Sequela
35 (1.1%)

Metronidazole Adverse Event Insights

3,306 reports name Metronidazole; 620 recorded a death outcome (18.8% of reported events, not a population-level mortality rate). Active ingredient: Metronidazole. Administration routes: Unknown, Oral, Intravenous, Parenteral.

By species: Dog (2,798 reports), Cat (353 reports), Unknown (138 reports). By breed: Retriever - Labrador (351), Domestic Shorthair (216), Unknown (153).

Leading clinical signs: Diarrhoea (929), Vomiting (880), Lethargy (see also Central nervous system depression in 'Neurological') (570), Other abnormal test result NOS (397). Outcome, 3,175 coded reports: Ongoing leads at 36.0%.

Read these counts as reporting volume, not risk: per our methodology, a widely-prescribed drug will rack up more raw FDA reports in a given year than a rarely-used one at an identical true rate, so we recommend comparing within similar-exposure products rather than across the full 2025 catalog.

Source: FDA Center for Veterinary Medicine openFDA Animal & Veterinary Adverse Events (CVM AER) · 2025

Every figure on PlainBreed is rendered directly from FDA openFDA adverse event data, no number is typed in by an editor. This page draws directly on FDA openFDA data, no figure is typed in by an editor. See our editorial standards & corrections policy, the methodology behind these numbers, or report a data error.