Pet Safety / Compounds / Metoprolol

Is Metoprolol safe for dogs and cats?

Moderate risk for pets

Beta-blocker toxicity in dogs from accidental ingestion of human metoprolol and other beta-blockers is a common ASPCA APCC emergency; dogs generally tolerate beta-blockers less well than humans, and therapeutic doses for dogs are different from human doses. Veterinary use: metoprolol is used in dogs for management of hypertrophic cardiomyopathy (HCM — less common in dogs than cats), supraventricular tachycardia, and systemic hypertension; dosing 0.4–1 mg/kg BID-TID. Accidental ingestion: ASPCA APCC data indicate bradycardia and hypotension at approximately 2–5 mg/kg; severe toxicity at >10 mg/kg; extended-release formulations (Toprol-XL) have delayed onset. Signs: bradycardia, weakness, lethargy, hypotension, possible AV block; pulmonary edema in severe cases. Treatment: atropine for bradycardia; glucagon 0.05–0.15 mg/kg IV (produces positive inotropy/chronotropy without beta-receptor); high-dose insulin euglycemia; IV fluids; calcium gluconate; pacing if necessary; intensive monitoring. Extended-release: Toprol-XL contains polymer-coated pellets — gastric decontamination with whole-bowel irrigation may be appropriate for large XL ingestions.

What is metoprolol?

The IUPAC name is 1-[4-(2-methoxyethyl)phenoxy]-3-(propan-2-ylamino)propan-2-ol.

Also known as: 1-[4-(2-methoxyethyl)phenoxy]-3-(propan-2-ylamino)propan-2-ol, (RS)-Metoprolol, Beatrolol, dl-Metoprolol.

IUPAC name
1-[4-(2-methoxyethyl)phenoxy]-3-(propan-2-ylamino)propan-2-ol
CAS number
37350-58-6
Molecular formula
C15H25NO3
Molecular weight
267.36 g/mol
SMILES
CC(C)NCC(COC1=CC=C(C=C1)CCOC)O
PubChem CID
4171

Risk for dogs

Moderate risk

Beta-blocker toxicity in dogs from accidental ingestion of human metoprolol and other beta-blockers is a common ASPCA APCC emergency; dogs generally tolerate beta-blockers less well than humans, and therapeutic doses for dogs are different from human doses. Veterinary use: metoprolol is used in dogs for management of hypertrophic cardiomyopathy (HCM — less common in dogs than cats), supraventricular tachycardia, and systemic hypertension; dosing 0.4–1 mg/kg BID-TID. Accidental ingestion: ASPCA APCC data indicate bradycardia and hypotension at approximately 2–5 mg/kg; severe toxicity at >10 mg/kg; extended-release formulations (Toprol-XL) have delayed onset. Signs: bradycardia, weakness, lethargy, hypotension, possible AV block; pulmonary edema in severe cases. Treatment: atropine for bradycardia; glucagon 0.05–0.15 mg/kg IV (produces positive inotropy/chronotropy without beta-receptor); high-dose insulin euglycemia; IV fluids; calcium gluconate; pacing if necessary; intensive monitoring. Extended-release: Toprol-XL contains polymer-coated pellets — gastric decontamination with whole-bowel irrigation may be appropriate for large XL ingestions.

Regulatory consensus

1 regulatory bodyhas classified Metoprolol.

AgencyYearClassificationNotes
FDA—Approved for hypertension, angina, heart failure (succinate XL formulation only), and acute MI management

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 metoprolol

  • 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 Metoprolol:

  • Alternative drug class; Non-pharmacological therapy; Lowest effective dose
    Trade-offs: Direct chemical substitution requires verification that the replacement does not introduce new hazards (regrettable substitution). Conduct full hazard assessment of proposed alternative before adoption.
    Relative cost: 1.2-2×

Frequently asked questions

Is metoprolol safe for pets?

Beta-blocker toxicity in dogs from accidental ingestion of human metoprolol and other beta-blockers is a common ASPCA APCC emergency; dogs generally tolerate beta-blockers less well than humans, and therapeutic doses for dogs are different from human doses. Veterinary use: metoprolol is used in dogs for management of hypertrophic cardiomyopathy (HCM — less common in dogs than cats), supraventricular tachycardia, and systemic hypertension; dosing 0.4–1 mg/kg BID-TID. Accidental ingestion: ASPCA APCC data indicate bradycardia and hypotension at approximately 2–5 mg/kg; severe toxicity at >10 mg/kg; extended-release formulations (Toprol-XL) have delayed onset. Signs: bradycardia, weakness, lethargy, hypotension, possible AV block; pulmonary edema in severe cases. Treatment: atropine for bradycardia; glucagon 0.05–0.15 mg/kg IV (produces positive inotropy/chronotropy without beta-receptor); high-dose insulin euglycemia; IV fluids; calcium gluconate; pacing if necessary; intensive monitoring. Extended-release: Toprol-XL contains polymer-coated pellets — gastric decontamination with whole-bowel irrigation may be appropriate for large XL ingestions.

What products contain metoprolol?

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

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Sources (2)
  1. FDA Prescribing Information: Metoprolol (Lopressor/Toprol-XL) — beta-1 selective; HFrEF MERIT-HF; abrupt discontinuation rebound; bradycardia contraindication; hypoglycemia masking; CYP2D6; glucagon antidote; succinate vs tartrate formulations (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 →