Drugs by active ingredient › Estradiol Benzoate + Trenbolone Acetate
Drug · combination of 2 active ingredients
Estradiol Benzoate + Trenbolone Acetate: adverse event reports
All products with this ingredient combination · 2 FDA-approved applications in the Green Book
- Mostly cattle reports
- Subcutaneous route most often
- Brands masked by FDA
FDA has received 342 adverse event reports in which a drug is recorded with the combination estradiol benzoate and trenbolone acetate as its active ingredients, from June 2014 to March 2026. The Green Book lists 2 FDA-approved applications with exactly this combination.
openFDA masks the brand and manufacturer in every report, so these figures describe the ingredient combination across all products and cannot be attributed to a brand.
In the 12 months to March 2026, 21 reports named it, down 40% from 35 in the 12 months before. FDA posts reports quarterly with a delay of three to six months, so the newest months are incomplete and usually grow in later releases. Over its whole reporting history that is about 29 reports a year and 0% of all 1,357,245 reports (0.8% of all cattle reports). How many animals received it is not published, so a count says nothing about how often a problem occurs per dose.
The most frequently coded terms are increased sexual interest (27.8%), death (14%) and sexual disorder NOS (11.4%). A report can list several signs, so shares add to more than 100%; 164 different terms appear across these reports. Increased sexual interest appears in 27.8% of these reports, a larger share than in the pooled reports for every drug containing trenbolone acetate (21.2%).
68.1% of reports concern cattle. Not every report describes illness: 32.7% as product or packaging defects. Of reports that state seriousness, 39.2% were classed as serious, and 21.6% of all reports record a death or euthanasia as an outcome, as reported. FDA has not necessarily determined whether any drug played a part.
Monthly reports by species, five years
Reports by the month FDA received them. Each panel has its own scale; the peak month is printed at the top right. The newest months are incomplete because FDA posts reports with a delay of three to six months.
Reports by year received
2026 covers reports received through March 2026 only.
Signs listed in reports
share of estradiol benzoate + trenbolone acetate reports listing the termall drugs containing trenbolone acetateall cattle reports
- Increased sexual interest27.8%95
- Death14%48
- Sexual disorder NOS[NOS: not otherwise specified]11.4%39
- Device Defective NOS[a product quality report, not a sign in an animal]9.6%33
- Implant, Abnormal9.4%32
- Containers, Damaged[a product quality report, not a sign in an animal]8.5%29
- Lack of efficacy - NOS[the product did not have the expected effect]5%17
- Increased weight3.8%13
- Death by euthanasia[the animal was euthanized]3.5%12
- Underfilling, Container[a product quality report, not a sign in an animal]2.9%10
- Aggression2.6%9
- Implant site abscess2.6%9
- Behavioural disorder NOS[behaviour change, type not specified]2.3%8
- Lameness2.3%8
- Musculoskeletal disorder NOS[NOS: not otherwise specified]2%7
- Color, Abnormal[a product quality report, not a sign in an animal]1.8%6
- Vocalisation[crying out or unusual noise]1.8%6
- Containers, Abnormal[a product quality report, not a sign in an animal]1.5%5
- Necropsy performed1.5%5
- Vaginal prolapse1.5%5
- Anaphylaxis[sudden severe allergic-type reaction]1.2%4
- Difficulty of Use[a product quality report, not a sign in an animal]1.2%4
- Found dead1.2%4
- Limping1.2%4
- Needlestick injury1.2%4
- No sign[no clinical sign was reported]1.2%4
- Penile protrusion1.2%4
- Recumbency[lying down and unable or unwilling to rise]1.2%4
Top 30 of 164 coded terms (VeDDRA, the veterinary reporting dictionary; plain-language gloss in brackets). One report can list several terms. The ticks show how often the same term appears in a wider pool of reports; they describe the reports, and FDA cautions that such figures cannot be used to estimate risk or to compare one product with another. openFDA masks brand and manufacturer names in adverse event records, so the reports counted here cannot be attributed to a particular brand.
Outcomes and report types
Outcome recorded in the report
What kind of report it was
Coloured bar: reports naming estradiol benzoate + trenbolone acetate. Grey bar: all 1,357,245 reports in the database. Outcomes are the status at the time of the last report, as stated by the reporter; a report covering several animals can carry more than one outcome. FDA has not necessarily determined whether any drug played a part in any outcome.
Species and breeds in the reports
Species
Single-breed animals
Breed shares follow how common each breed is. Crossbred animals and reports with no breed stay in the species figure only.
Age, weight and route
Age of the animal
Weight of the animal
Route of administration stated in reports: subcutaneous (68), other (1), parenteral (1).
In context
| Measure | Estradiol Benzoate + Trenbolone Acetate | All drugs containing trenbolone acetate | All cattle reports | All reports |
|---|---|---|---|---|
| Reports | 342 | 642 | 31,229 | 1,357,245 |
| Share of that pool's reports naming this drug | — | 53.3% | 0.8% | 0% |
| Classed serious, of reports stating it | 39.2% | 44% | 58.4% | 38.6% |
| Death or euthanasia recorded, per 1,000 reports | 216.4 | 265 | 368 | 63.8 |
| Filed as lack of expected effectiveness (wholly or partly) | 5.6% | — | — | 23% |
| Top term, share of reports | Increased sexual interest 27.8% | 21.2% | 0.8% | — |
The trenbolone acetate pool is every report naming trenbolone acetate alone or in any combination; this combination accounts for 53.3% of it. Shares are of reports, not of animals treated. The number of doses sold is not public, so none of these figures is a rate of occurrence, and differences between columns reflect which animals receive a drug and who reports as much as anything else.
Other ingredient sets sharing an ingredient
| Active ingredients | Reports | Latest 12 months |
|---|---|---|
| Estradiol Benzoate + Progesterone | 290 | 6 |
| Estradiol + Trenbolone Acetate | 267 | 16 |
| Estradiol + Trenbolone Acetate + Tylosin Tartrate | 31 | 4 |
| Estradiol Benzoate + Testosterone Propionate | 30 | 2 |
Listed for navigation, ordered by report count. FDA states that these data "cannot be used to estimate the risk associated with the product or compare one drug or device product with another": drugs differ in formulation, in the animals they are given to, in sales volume and in years on the market. A report's ingredient field can be incomplete, so reports about one product may sit under more than one set.
FDA-approved products containing this combination (Green Book)
Reference information, not report statistics. openFDA masks brand and manufacturer names in adverse event records, so the reports counted here cannot be attributed to a particular brand. The list below is the FDA Green Book as of 30 Sep 2026; nothing on this page says which of these products, if any, a report concerned.
| Trade name | Active ingredients | Sponsor | Approved for | Application |
|---|---|---|---|---|
| Synovex Choice; Synovex Plus; Synovex Primer | Estradiol Benzoate, Trenbolone Acetate | Zoetis Inc. | Cattle | NADA 141-043 |
| Synovex ONE Feedlot; Synovex ONE Grower | Estradiol Benzoate, Trenbolone Acetate | Zoetis Inc. | — | NADA 141-348 |
Species are the major species the Green Book search lists for the application ("—" where it lists another species or none). Approval dates are not part of the Green Book listing files and are not shown. Pioneer applications (NADA) come first, then generics (ANADA).
Questions about estradiol benzoate + trenbolone acetate reports
How many adverse event reports has FDA received for the combination estradiol benzoate and trenbolone acetate?
342 reports record a drug with the combination estradiol benzoate and trenbolone acetate as its active ingredients in the openFDA release of 28 Sep 2026, covering reports received through March 2026. 21 of them arrived in the latest 12 months.
Which brand do these reports concern?
That cannot be known from the public data. openFDA masks brand and manufacturer names in adverse event records, so the reports counted here cannot be attributed to a particular brand. The Green Book lists 2 approved applications with this combination; the reference list on this page names them without any counts.
What signs are reported most often?
increased sexual interest (27.8%), death (14%), sexual disorder NOS (11.4%), device Defective NOS (9.6%) and implant, Abnormal (9.4%). These are the coded terms listed in reports; several can appear in one report, and a term's presence is not a finding that the drug was responsible.
Which species and breeds appear in these reports?
cattle (68.1%) and human exposure (1.2%). Among single-breed animals the most frequent labels are Holstein-Friesian, Aberdeen Angus and Corriente; popular breeds appear often in any drug's reports because there are more of them.
Are reports rising?
21 reports in the 12 months to March 2026, down 40% from 35 in the 12 months before. FDA posts reports quarterly with a delay of three to six months, so the newest months are incomplete and usually grow in later releases. Counts also move with sales, publicity and time on the market.
Do these reports show that estradiol benzoate + trenbolone acetate harms pets?
Report counts cannot show that. FDA states that "there is no certainty that the reported drug or device caused the adverse event" and that the event "may have been related to an underlying disease, other drugs used at the same time or other non-drug related sources." FDA also notes that commonly used products may have more reports simply because more animals receive them.
Are these the side effects of estradiol benzoate + trenbolone acetate?
They are signs listed in reports, not an established list of side effects. The adverse reactions observed in studies are printed on each product's FDA-approved label, which a veterinarian can go through with you. This page is a record of what was reported to FDA.
How do I report a problem with an animal drug?
FDA asks owners and veterinarians to call the drug company first (the number is on the label); companies must pass reports to FDA. Reports can also go directly to FDA on Form FDA 1932a. See the guide on how to report.
Where this comes from. Counts are built from the openFDA Animal & Veterinary adverse event bulk files released 28 Sep 2026, which hold reports FDA's Center for Veterinary Medicine received through 31 Mar 2026. openFDA masks brand and manufacturer names in these files, so drugs are counted by the active ingredients each record discloses and no figure is attributed to a brand, application or company. Ingredient names, and the separate reference lists of approved products, follow the FDA Green Book as of 30 Sep 2026. Drug entries are grouped by the active ingredients their unmasked ingredient field discloses; the application number that records also carry is not used. No report text, lot numbers or reporter details are published. See the methodology and sources; FDA's record is authoritative, and corrections are handled within five working days.