Is Zeranol (Ralgro) safe for dogs and cats?
Low risk for petsNo direct veterinary use; incidental exposure through contaminated feed unlikely to reach effect levels.
What is zeranol (ralgro)?
The IUPAC name is (4S,8R)-8,16,18-trihydroxy-4-methyl-3-oxabicyclo[12.4.0]octadeca-1(14),15,17-trien-2-one.
Also known as: ZERANOL, Zearalanol, alpha-Zearalanol, Ralabol.
- IUPAC name
- (4S,8R)-8,16,18-trihydroxy-4-methyl-3-oxabicyclo[12.4.0]octadeca-1(14),15,17-trien-2-one
- CAS number
- 26538-44-3
- Molecular formula
- C18H26O5
- Molecular weight
- 322.4 g/mol
- SMILES
- C[C@@H]1CCCC(=O)CCC/C=C\c2cc(O)cc(O)c2OC1=O
- PubChem CID
- 2999413
Risk for dogs
Low riskNo direct veterinary use; incidental exposure through contaminated feed unlikely to reach effect levels.
Regulatory consensus
4 regulatory and scientific bodies have classified Zeranol (Ralgro). The classifications differ — that's the data.
| Agency | Year | Classification | Notes |
|---|---|---|---|
| FDA | 1969 | Approved animal growth promoter (NADA 038-233) | |
| EU | 1989 | Banned — Directive 96/22/EC (hormone ban) | |
| Codex Alimentarius | 2015 | ADI 0–0.5 µg/kg bw; MRL established for cattle | |
| IARC | 1993 | Not formally evaluated; structurally related to zearalenone (Group 3) |
Regulators apply different standards of evidence — animal-data weighting, exposure-pattern assumptions, epidemiological power thresholds — which is why two scientific bodies can review the same data and reach different conclusions. The disagreement is the data.
Where pets encounter zeranol (ralgro)
- Veterinary Medicine
- Food Contaminant
Safer alternatives
Lower-risk approaches that achieve a similar outcome to Zeranol (Ralgro):
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Non-hormone growth strategies (improved genetics, nutrition)
Trade-offs: Removes 95-99% of dissolved contaminants including metals, PFAS, nitrates; wastes 2-4 gallons per gallon produced (improving with newer systems); removes beneficial minerals; $0.05-0.25/gallon; requires pre-treatment for longevity.Relative cost: 1.2-2×
-
Ractopamine (beta-agonist — also controversial)
Trade-offs: Removes 95-99% of dissolved contaminants including metals, PFAS, nitrates; wastes 2-4 gallons per gallon produced (improving with newer systems); removes beneficial minerals; $0.05-0.25/gallon; requires pre-treatment for longevity.Relative cost: 1.2-2×
Frequently asked questions
Is zeranol (ralgro) safe for pets?
No direct veterinary use; incidental exposure through contaminated feed unlikely to reach effect levels.
Why do regulators disagree about zeranol (ralgro)?
Zeranol (Ralgro) has been classified by 4 agencies including FDA, EU, Codex Alimentarius, IARC, with differing conclusions. Regulators apply different standards of evidence (animal data weighting, exposure-pattern assumptions, epidemiological power thresholds), which is why two scientific bodies can review the same data and reach different conclusions. See the regulatory consensus table on this page for the full picture.
See Zeranol (Ralgro) in the pets app
Look up products containing zeranol (ralgro), compare to alternatives, and explore the full data record.
Open in pets View raw API dataSources (1)
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Reference data, not professional advice. Aggregates publicly available regulatory and scientific data; not a substitute for veterinary, medical, legal, or regulatory advice. Why we built ALETHEIA →