Drug profile

The FDA adverse-event record for Phenylbutazone

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

131
adverse-event reports
15.3%
death-coded share
Horse
most-reported species
17
Colic - 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.
131
Total Reports
20
Deaths Reported
15.3%
Death Rate

Active Ingredients

Phenylbutazone

Administration Routes

UnknownOralIntravenousParenteral

Species Affected

Horse 94
Unknown 30
Dog 4
Other 1
Other Equids 1
Donkey 1

Most Affected Breeds

Unknown 39
Quarter Horse 30
Thoroughbred 11
Horse (unknown) 10
Warmblood (unspecified) 6
Arab 5
Paint 3
Standardbred (unspecified) 3
Tennessee Walking Horse 3
Hanovarian 2

Most Reported Reactions

Colic 17
Injection site swelling 13
Elevated blood urea nitrogen (BUN) 13
Elevated creatinine 13
Lethargy (see also Central nervous system depression in 'Neurological') 10
Death by euthanasia 10
Polyuria 10
Polydipsia 10
Fever 9
Decreased appetite 8
Lameness 7
Tachycardia 7

Outcome Breakdown

Recovered/Normal
36 (35.3%)
Outcome Unknown
35 (34.3%)
Euthanized
11 (10.8%)
Ongoing
9 (8.8%)
Died
9 (8.8%)
Recovered with Sequela
2 (2.0%)

Phenylbutazone Adverse Event Insights

131 reports name Phenylbutazone; 20 recorded a death outcome (15.3% of reported events, not a population-level mortality rate). Active ingredient: Phenylbutazone. Administration routes: Unknown, Oral, Intravenous, Parenteral.

By species: Horse (94 reports), Unknown (30 reports), Dog (4 reports). By breed: Unknown (39), Quarter Horse (30), Thoroughbred (11).

Leading clinical signs: Colic (17), Injection site swelling (13), Elevated blood urea nitrogen (BUN) (13), Elevated creatinine (13). Outcome, 102 coded reports: Recovered/Normal leads at 35.3%.

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.