Pet Safety / Compounds / Florfenicol

Is Florfenicol safe for dogs and cats?

Moderate risk for pets

Not commonly used in dogs; can cause GI upset, reduced appetite. Off-label use occasionally for susceptible infections.

What is florfenicol?

The IUPAC name is 2,2-dichloro-N-[(1R,2S)-3-fluoro-1-hydroxy-1-(4-methylsulfonylphenyl)propan-2-yl]acetamide.

Also known as: Nuflor, (-)-Florfenicol, Sch-25298, Sch 25298.

IUPAC name: 2,2-dichloro-N-[(1R,2S)-3-fluoro-1-hydroxy-1-(4-methylsulfonylphenyl)propan-2-yl]acetamide
CAS number: 73231-34-2
Molecular formula: C12H14Cl2FNO4S
Molecular weight: 358.21 g/mol
SMILES: O=C(C(O)c1ccc(S(=O)(=O)C)cc1)NC(CS)C(F)F
PubChem CID: 114811

Risk for dogs

Moderate risk

Not commonly used in dogs; can cause GI upset, reduced appetite. Off-label use occasionally for susceptible infections.

Risk for cats

Moderate risk

Not routinely used in cats; bone marrow suppression possible at high doses. Avoid prolonged use.

Regulatory consensus

3 regulatory and scientific bodies have classified Florfenicol. The classifications differ — that's the data.

Agency	Year	Classification
FDA	1996	Approved veterinary drug (NADA 141-063)
EU	2010	Annex I — MRL established (Reg 37/2010)
Codex Alimentarius	2018	MRLs set for cattle/pig/chicken/fish

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 florfenicol

Veterinary Medicine

Safer alternatives

Lower-risk approaches that achieve a similar outcome to Florfenicol:

Oxytetracycline (older, well-characterized)
Trade-offs: Alternative approach; specific tradeoffs depend on application context, scale, and regulatory requirements. Full hazard assessment of alternative recommended before adoption to avoid regrettable substitution.

Relative cost: 1.2-2×
Tulathromycin (respiratory)
Trade-offs: Non-halogenated; no toxic combustion gases (HCl, dioxins); requires higher loading (40-65% by weight vs 5-15% for halogenated FRs); affects material properties (density, flexibility, processability); cost-effective at scale.

Relative cost: 1.2-2×

Frequently asked questions

Is florfenicol safe for pets?

Not commonly used in dogs; can cause GI upset, reduced appetite. Off-label use occasionally for susceptible infections.

Why do regulators disagree about florfenicol?

Florfenicol has been classified by 3 agencies including FDA, EU, Codex Alimentarius, 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 Florfenicol in the pets app

Look up products containing florfenicol, compare to alternatives, and explore the full data record.

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Sources (1)

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 →