Drug profile

The FDA adverse-event record for Altrenogest

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

86
adverse-event reports
2.3%
death-coded share
Unknown
most-reported species
19
Unclassifiable adverse event - top reaction
Verify with FDA CVM →
Important: Adverse event reports do not establish that a drug caused or contributed to the event. Consult your veterinarian before making treatment decisions.
86
Total Reports
2
Deaths Reported
2.3%
Death Rate

Active Ingredients

Altrenogest

Administration Routes

UnknownOralTopical

Species Affected

Unknown 35
Horse 23
Human 18
Pig 10

Most Affected Breeds

Unknown 53
Quarter Horse 6
Pig (unknown) 6
Horse (unknown) 5
Arab 2
Warmblood - Dutch 2
Crossbred Porcine/Pig 2
Mixed (Pig) 1
Belgian Draft, also called Brabant or Brabants trekpaard 1
Welsh Pony 1

Most Reported Reactions

Unclassifiable adverse event 19
Accidental exposure 17
Containers, Leaking 16
INEFFECTIVE, ESTRUS SUPPRESSIO 8
Rash 5
Vials, Leaking 5
Closure, Abnormal 5
Caps, Abnormal 4
Abdominal pain 4
INEFFECTIVE, ESTRUS SYNCHRONIZ 4
Disorders of menstrual cycle NOS 4
Restlessness 4

Outcome Breakdown

Outcome Unknown
6 (42.9%)
Ongoing
5 (35.7%)
Died
1 (7.1%)
Euthanized
1 (7.1%)
Recovered/Normal
1 (7.1%)

Altrenogest Adverse Event Insights

86 reports name Altrenogest; 2 recorded a death outcome (2.3% of reported events, not a population-level mortality rate). Active ingredient: Altrenogest. Administration routes: Unknown, Oral, Topical.

By species: Unknown (35 reports), Horse (23 reports), Human (18 reports). By breed: Unknown (53), Quarter Horse (6), Pig (unknown) (6).

Leading clinical signs: Unclassifiable adverse event (19), Accidental exposure (17), Containers, Leaking (16), INEFFECTIVE, ESTRUS SUPPRESSIO (8). Outcome, 14 coded reports: Outcome Unknown leads at 42.9%.

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.