Pet Safety / Compounds / Furosemide

Is Furosemide safe for dogs and cats?

Low risk for pets

Furosemide is one of the most important drugs in veterinary medicine — FDA-approved for veterinary use (Lasix Injection, Disal Oral) for management of congestive heart failure (CHF) in dogs and cats, pulmonary edema, and edema; it is the first-line diuretic for canine cardiac disease. Veterinary dosing (dogs): 2–4 mg/kg every 8–12 hours orally; emergency IV dosing 4–8 mg/kg for acute CHF/pulmonary edema. Canine CHF: dilated cardiomyopathy (DCM) in large breeds (Great Danes, Dobermans) and myxomatous mitral valve disease (MMVD) in small breeds are the main canine cardiac diseases requiring furosemide; EPIC and QUEST trials established early treatment protocols. Electrolytes in dogs: same hypokalemia concern as humans; potassium supplementation or concurrent spironolactone (aldosterone antagonist) often prescribed; hypomagnesemia from chronic furosemide contributes to arrhythmia risk in cardiac dogs. Accidental ingestion: deliberate or accidental single-dose excess causes dehydration and electrolyte imbalance; clinical signs in non-cardiac dogs are primarily diuresis-related (polyuria, dehydration, weakness); without underlying cardiac disease, single-dose OD is generally manageable with supportive care. Furosemide-deafness in cats: high-dose IV furosemide in cats has caused deafness — particularly relevant in acute pulmonary edema treatment; use lowest effective dose.

What is furosemide?

The IUPAC name is 4-chloro-2-(furan-2-ylmethylamino)-5-sulfamoylbenzoic acid.

Also known as: 4-chloro-2-(furan-2-ylmethylamino)-5-sulfamoylbenzoic acid, Frusemide, Lasix, Furanthril.

IUPAC name
4-chloro-2-(furan-2-ylmethylamino)-5-sulfamoylbenzoic acid
CAS number
54-31-9
Molecular formula
C12H11ClN2O5S
Molecular weight
330.74 g/mol
SMILES
C1=COC(=C1)CNC2=CC(=C(C=C2C(=O)O)S(=O)(=O)N)Cl
PubChem CID
3440

Risk for dogs

Low risk

Furosemide is one of the most important drugs in veterinary medicine — FDA-approved for veterinary use (Lasix Injection, Disal Oral) for management of congestive heart failure (CHF) in dogs and cats, pulmonary edema, and edema; it is the first-line diuretic for canine cardiac disease. Veterinary dosing (dogs): 2–4 mg/kg every 8–12 hours orally; emergency IV dosing 4–8 mg/kg for acute CHF/pulmonary edema. Canine CHF: dilated cardiomyopathy (DCM) in large breeds (Great Danes, Dobermans) and myxomatous mitral valve disease (MMVD) in small breeds are the main canine cardiac diseases requiring furosemide; EPIC and QUEST trials established early treatment protocols. Electrolytes in dogs: same hypokalemia concern as humans; potassium supplementation or concurrent spironolactone (aldosterone antagonist) often prescribed; hypomagnesemia from chronic furosemide contributes to arrhythmia risk in cardiac dogs. Accidental ingestion: deliberate or accidental single-dose excess causes dehydration and electrolyte imbalance; clinical signs in non-cardiac dogs are primarily diuresis-related (polyuria, dehydration, weakness); without underlying cardiac disease, single-dose OD is generally manageable with supportive care. Furosemide-deafness in cats: high-dose IV furosemide in cats has caused deafness — particularly relevant in acute pulmonary edema treatment; use lowest effective dose.

Regulatory consensus

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

AgencyYearClassificationNotes
EPA CTX / IARC—Group 3 - Not classifiable as to its carcinogenicity to humans
EPA CTX / Genetox—Genotoxicity: negative (Ames: negative, 0 positive / 3 negative reports)
EPA CTX / Genetox—Genotoxicity: negative (Ames: negative, 0 positive / 3 negative reports)

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 furosemide

  • Industrial Facilities — Manufacturing plants, Chemical storage areas, Waste treatment sites
  • Occupational Environments — Factories, Warehouses, Transportation vehicles

Safer alternatives

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

  • Therapeutic alternatives (consult prescriber)
    Trade-offs: Drug-specific. Cannot substitute without medical guidance.
    Relative cost: 1.2-2×

Frequently asked questions

Is furosemide safe for pets?

Furosemide is one of the most important drugs in veterinary medicine — FDA-approved for veterinary use (Lasix Injection, Disal Oral) for management of congestive heart failure (CHF) in dogs and cats, pulmonary edema, and edema; it is the first-line diuretic for canine cardiac disease. Veterinary dosing (dogs): 2–4 mg/kg every 8–12 hours orally; emergency IV dosing 4–8 mg/kg for acute CHF/pulmonary edema. Canine CHF: dilated cardiomyopathy (DCM) in large breeds (Great Danes, Dobermans) and myxomatous mitral valve disease (MMVD) in small breeds are the main canine cardiac diseases requiring furosemide; EPIC and QUEST trials established early treatment protocols. Electrolytes in dogs: same hypokalemia concern as humans; potassium supplementation or concurrent spironolactone (aldosterone antagonist) often prescribed; hypomagnesemia from chronic furosemide contributes to arrhythmia risk in cardiac dogs. Accidental ingestion: deliberate or accidental single-dose excess causes dehydration and electrolyte imbalance; clinical signs in non-cardiac dogs are primarily diuresis-related (polyuria, dehydration, weakness); without underlying cardiac disease, single-dose OD is generally manageable with supportive care. Furosemide-deafness in cats: high-dose IV furosemide in cats has caused deafness — particularly relevant in acute pulmonary edema treatment; use lowest effective dose.

What products contain furosemide?

Furosemide appears in: Manufacturing plants (Industrial facilities); Chemical storage areas (Industrial facilities); Factories (Occupational environments); Warehouses (Occupational environments).

Why do regulators disagree about furosemide?

Furosemide has been classified by 3 agencies including EPA CTX / IARC, EPA CTX / Genetox, EPA CTX / Genetox, 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.

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Sources (2)
  1. FDA Prescribing Information: Furosemide (Lasix) — loop diuretic; NKCC2 inhibition; hypokalemia; ototoxicity; neonatal nephrocalcinosis; bioavailability variability in HF; diuretic resistance; sulfonamide moiety; veterinary CHF first-line (2023) (2023) — regulatory
  2. ASPCA Animal Poison Control Center: Cardiac Drug Toxicosis in Pets — statin myopathy in cats; beta-blocker bradycardia dogs; CCB toxicity (amlodipine/diltiazem); ACE inhibitor renal effects; warfarin anticoagulant; furosemide; toxic dose thresholds (2023) (2023) — veterinary

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 →