Pet Drug Reports

Estradiol Benzoate: adverse event reports in all combinations

Active ingredient, alone and in combinations

Brand names with this ingredient: Synovex, Component.

The openFDA records give the value "MSK" for the brand name and for the manufacturer name of each drug. FDA says that MSK means "masked". So the site cannot count a report for a brand.

Read this first. FDA says this about the data:

An API dataset query result cannot be used to estimate the risk associated with the product or compare one drug or device product with another. When looking at the results, be aware that there is no certainty that the reported drug or device caused the adverse event. This dataset should not be the sole source of information for clinical decision-making or other assumptions about the safety or effectiveness of a product. The adverse event may have been related to an underlying disease, other drugs used at the same time or other non-drug related sources.

FDA Center for Veterinary Medicine publishes these words. Source: Adverse Event Reports for Animal Drugs and Devices, read on . The data have the reports that FDA received through .

This page is not veterinary advice. For an animal that is ill, speak to a veterinarian.

Contacting a veterinarianHow to report to FDA

FDA reports received through . Counts include this ingredient alone and in combinations. Why brand names have no separate count.

From May 1990 to June 2026, FDA received 661 adverse event reports that name a drug with estradiol benzoate, alone or in a combination. 3 sets of active ingredients with estradiol benzoate have a drug page.

Of the 661 reports, 434 (65.7%) are about cattle. 9 reports are about people who were exposed to the drug (1.4%). In January to March 2026, FDA received 7 reports that name estradiol benzoate, alone or in a combination. The signs that appear in the largest number of the 661 reports are "Death", "Increased sexual interest" and "Implant, Abnormal". A report is not proof that a drug caused a sign.

Reports that name this ingredient fell by 31.7% in the 12 months to June 2026, compared with the 12 months before. Reports for all animal drugs fell by 4.6% in the same periods. The newest months can get more reports in a later update. Reports about cattle are 65.7% of the reports that name this ingredient, and 2.3% of all reports.

Search engines list an ingredient page with 500 reports or more in all years. The page also needs 30 reports or more in the 12 months to June 2026. This page is under one of these numbers. The site keeps the page and keeps it out of search engines.

Reports in the latest closed quarter

Reports that name estradiol benzoate, by the quarter in which FDA received them
SpeciesJan to Mar 2026Oct to Dec 2025Jan to Mar 2025
All species7611
Dog000
Cat000
Horse000
Other or not given7611

January to March 2026 is the latest closed quarter in the data.

All updatesFeed of updates (RSS)

Drug pages with estradiol benzoate

A report names a drug by its set of active ingredients. Each set with estradiol benzoate that has a drug page is in the table, in order of name. The table has 3 sets.

Drug pages with estradiol benzoate, in order of name, with the reports of each page
Active ingredientsReports, all yearsReports, latest 12 months
Estradiol Benzoate + Progesterone2904
Estradiol Benzoate + Testosterone Propionate301
Estradiol Benzoate + Trenbolone Acetate34421

A report can name more than one set, so the counts of the sets can add to more than the count of the page.

An API dataset query result cannot be used to estimate the risk associated with the product or compare one drug or device product with another.

FDA Center for Veterinary Medicine. Source: Adverse Event Reports for Animal Drugs and Devices

Signs that the reports list

A sign is a coded term from the report. The words in brackets are a plain gloss of the term. The percentage is the share of the 661 reports that list the sign. One report can list more than one sign and more than one drug.

The sign that is in the largest number of the reports comes first.

  1. Death18%119 reports
  2. Implant, Abnormal11.5%76 reports
  3. Device Defective NOS[a product quality report, not a sign in an animal]6.8%45 reports
  4. Sexual disorder NOS[NOS: not otherwise specified]6.5%43 reports
  5. Containers, Damaged[a product quality report, not a sign in an animal]5.7%38 reports
  6. Underfilling, Package[a product quality report, not a sign in an animal]4.8%32 reports
  7. Lack of efficacy - NOS[the product did not have the expected effect]4.4%29 reports
  8. Anaphylaxis[sudden severe allergic-type reaction]4.1%27 reports
  9. Ineffective, weight inc[legacy FDA term: the product did not have the expected effect (weight inc)]3.6%24 reports
  10. Death by euthanasia[the animal was euthanized]2.7%18 reports
  11. Dyspnoea[difficulty breathing]2.7%18 reports
  12. Underfilling, Container[a product quality report, not a sign in an animal]2.6%17 reports
Show the next 16 signs
  1. Recumbency[lying down and unable or unwilling to rise]2.4%16 reports
  2. Tablets, Abnormal[a product quality report, not a sign in an animal]2.3%15 reports
  3. Implant site abscess2.1%14 reports
  4. Aggression2%13 reports
  5. Containers, Abnormal[a product quality report, not a sign in an animal]2%13 reports
  6. Hypersalivation[drooling]2%13 reports
  7. Increased weight2%13 reports
  8. Behavioural disorder NOS[behaviour change, type not specified]1.8%12 reports
  9. No sign[no clinical sign was reported]1.8%12 reports
  10. Rectal prolapse1.8%12 reports
  11. Lameness1.7%11 reports
  12. Vaginal prolapse1.7%11 reports
  13. Lack of efficacy (bacteria) - NOS[the product did not have the expected effect: target not specified]1.5%10 reports
  14. Mammary gland disorder NOS[NOS: not otherwise specified]1.5%10 reports
  15. Color, Abnormal[a product quality report, not a sign in an animal]1.4%9 reports
  16. Dispenser, Abnormal[a product quality report, not a sign in an animal]1.4%9 reports

Download all signs (CSV)

Reports by species

Reports for each month, Jul 2021 to Jun 2026

Dog0 reports

No chart: no month has 5 or more reports.

Cat0 reports

No chart: no month has 5 or more reports.

Horse0 reports

No chart: no month has 5 or more reports.

Other or not given166 reports. Largest count in one month: 8 (Jul 2023)

The month is the month in which FDA received the report. Each chart has its own scale. FDA says that a report can take 3 to 6 months to reach the public data. The newest months can get more reports in a later update.

Reports by year

  • Dog
  • Cat
  • Horse
  • Other or not given
Reports that name estradiol benzoate, by the year in which FDA received them and by species
YearDogCatHorseOther or not givenAll species
202600099
20250003434
20240004141
20230003838
20220002525
20210003636
20200004343
20190004949
20180016364
20170005858
20160008989
20150001717
20140001212
201300088
201200077
20110011920
20100011617
200900066
20080001111
200700044
200600044
200500011
200400055
200300189
200200066
20010001111
20000001414
199900134
199800088
199700055
199600022
199500011
199400011
199000022

2026 has the reports that FDA received through Jun 2026. Download the years (CSV)

What the reports record

Outcome at the time of the report

  • Recovered/Normal7.3%48
  • Recovered with Sequela[recovered, with a lasting effect]2%13
  • Ongoing2.3%15
  • Died22.5%149
  • Euthanized2.4%16
  • Outcome Unknown39.6%262

An outcome in a report is not proof that the drug caused it. The person who sends the report gives the outcome. Each share is of the 661 reports that name estradiol benzoate.

Kind of report

  • Safety issue58.2%385
  • Lack of expected effectiveness5.9%39
  • Both safety and lack of expected effectiveness1.2%8
  • Manufacturing or product defect34.6%229
  • Other0%0

Age of the animal

  • Under 1 year16%106
  • 1 to 3 years8%53
  • 4 to 7 years0.5%3
  • 8 to 11 years0%0
  • 12 years and over1.2%8
  • Age not given74.3%491

Each share of kind and age is of the 661 reports that name estradiol benzoate.

Approved animal drugs with this active ingredient (FDA Green Book)

This section is reference data. It has no report count.

The openFDA records give the value "MSK" for the brand name and for the manufacturer name of each drug. FDA says that MSK means "masked". So the site cannot count a report for a brand.

Brand names

  • Synovex
  • Component

What the Green Book records give

Applications with an approval in force
5
Approved species
Cattle
Dose forms
Implant, Extended-release implants, Subcutaneous Implant
Routes
Subcutaneous
Sale
OTC (over the counter), RX (prescription)
Earliest approval date in the records

The species, dose forms and routes are the words of the Green Book records for all the applications together. One product can have fewer. The label of a product gives its approved use.

Applications in the Green Book of 2 Nov 2026, pioneer applications (NADA) first
Brand nameActive ingredientsSponsorApproved speciesApplication
Synovex CEstradiol Benzoate, ProgesteroneZoetis Inc.CattleNADA 009-576
Synovex HEstradiol Benzoate, Testosterone PropionateZoetis Inc.CattleNADA 011-427
Component E-C with Tylan; Component E-S with Tylan; Component E-CEstradiol Benzoate, Progesterone, Tylosin TartrateElanco US Inc.CattleNADA 110-315
Synovex Choice; Synovex Plus; Synovex PrimerEstradiol Benzoate, Trenbolone AcetateZoetis Inc.CattleNADA 141-043
Synovex ONE Feedlot; Synovex ONE GrowerEstradiol Benzoate, Trenbolone AcetateZoetis Inc.Not in the list of major speciesNADA 141-348
Celerinapproval withdrawnEstradiol BenzoatePR Pharmaceuticals, Inc.CattleNADA 141-040
Celerin Capproval withdrawnEstradiol BenzoatePR Pharmaceuticals, Inc.CattleNADA 141-041

FDA pages for this ingredient

The site checked these addresses on . The links open in a new tab.

Cite this page

Pet Drug Reports. Estradiol Benzoate, all combinations: adverse event reports that FDA received. https://petdrugreports.com/ingredient/estradiol-benzoate/ Source: FDA Center for Veterinary Medicine, openFDA Animal and Veterinary adverse event reports, export of . Reports received through .

Where the data come from

The counts come from the openFDA Animal and Veterinary adverse event files, export of 30 Oct 2026. The files have the reports that the FDA Center for Veterinary Medicine received through 26 Jun 2026. The files mask brand and manufacturer names. The site counts a drug by the active ingredients that each record gives, and gives no count to a brand, an application or a company. Ingredient names and the lists of approved products follow the FDA Green Book of 2 Nov 2026. Ingredient names follow the Green Book, with salts and forms as FDA lists them.

The site does not publish report text, lot numbers or details of a reporter. FDA's record is the authority. See how the site counts reports, the data sources and the corrections page.

Questions about these reports

Which brand are these reports about?

The openFDA records give the value "MSK" for the brand name and for the manufacturer name of each drug. FDA says that MSK means "masked". So the site cannot count a report for a brand. The Green Book section of this page lists brand names with this active ingredient.

Do the reports show that the ingredient caused the signs?

No. A report can name more than one drug, and a drug can have more than one active ingredient. FDA states this about the data.

When looking at the results, be aware that there is no certainty that the reported drug or device caused the adverse event.

The adverse event may have been related to an underlying disease, other drugs used at the same time or other non-drug related sources.

FDA Center for Veterinary Medicine. Source: Adverse Event Reports for Animal Drugs and Devices

How many reports did FDA receive in the latest 12 months?

FDA received 28 reports in the 12 months to June 2026. It received 41 reports in the 12 months before. FDA says that a report can take 3 to 6 months to reach the public data. The newest months can get more reports in a later update.

What kinds of report are in the count?

Of the 661 reports received from May 1990 to June 2026, 58.2% are about a safety issue only. 7.1% are about a lack of expected effectiveness, alone or with a safety issue. 34.6% are about a defect of the product or its package.