Captopril: veterinary dose and monograph

At a glance

Drug class

Cardiovascular

Also known as

Capoten, Aceten, Angiopril

Species with doses

Dogs and Cats

General dose range

0.5–2 mg/kg PO q8–12h — check the species tables for the indication

Routes

PO

Last reviewed

1 October 2026

Indications

• Congestive heart failure (with diuretics ± pimobendan)
• Systemic hypertension
• Proteinuric kidney disease (reduces proteinuria)
• Afterload reduction (largely superseded by longer-acting ACE inhibitors)

Captopril dose by species

Doses are per administration unless stated. mg/kg doses scale with body weight; per-animal, per-quarter and infusion-rate doses are shown as the reference writes them.

Dogs

• CHF / hypertension: Papich 5e and Plumb’s p.189: 0.5–2 mg/kg PO q8–12h (Atkins — three times daily). Enalapril, benazepril and other newer ACE inhibitors have largely replaced it. Start low with diuretics; monitor creatinine and potassium.

Cats

• Hypertension / CHF: Plumb’s p.189: cardiomyopathy 0.55–1.54 mg/kg PO q8–12h (Kittleson); ¼–½ of a 12.5 mg tablet q8–12h (Bonagura). Papich 5e: 3.12–6.25 mg per cat q8h. Monitor renal values and potassium.

Contraindications

Bilateral renal artery stenosis, pre-existing hypotension, dehydration/hypovolaemia, hyperkalaemia, and outflow-tract obstruction. Pregnancy (ACE-inhibitor fetotoxicity). Caution with other RAAS drugs/diuretics. Known ACE-inhibitor hypersensitivity.

Adverse effects

• Hypotension (especially first dose with diuretics)
• Azotaemia / reduced GFR; hyperkalaemia
• GI upset (vomiting, anorexia)
• Short duration → frequent dosing needed

Drug interactions

• Diuretics (furosemide): additive hypotension/azotaemia — start low, monitor
• Potassium-sparing diuretics/K supplements: hyperkalaemia
• NSAIDs: blunt effect and increase nephrotoxicity
• Other antihypertensives: additive hypotension

Pregnancy and lactation

Contraindicated in pregnancy — ACE inhibitors are fetotoxic.

Monitoring

• Renal values and potassium at baseline and after starting/changes
• Blood pressure; resting respiratory rate (CHF)
• Urine protein:creatinine in proteinuric patients

Toxicity and overdose

Overdose: hypotension, weakness, azotaemia, hyperkalaemia — as for the ACE-inhibitor class. First-dose hypotension and renal decompensation (with aggressive diuretics/volume depletion) are the main hazards.

Management: No specific antidote. IV fluids for hypotension (cautiously in cardiac patients), treat hyperkalaemia, support renal function; vasopressors if refractory. Monitor renal values and electrolytes.

Clinical pearls

• The original ACE inhibitor, now largely a historical/second choice — its short duration means q8–12h dosing, whereas enalapril/benazepril/ramipril give once/twice-daily convenience
• Same class benefits and cautions as other ACE inhibitors (start low with diuretics; watch renal values/potassium)
• Prefer a longer-acting ACE inhibitor for routine CHF/hypertension/proteinuria management

Mechanism of action

Inhibits angiotensin-converting enzyme, blocking conversion of angiotensin I to angiotensin II and reducing aldosterone — producing arteriolar/venous dilation (reduced afterload/preload), lower blood pressure, reduced sodium/water retention, and lower intraglomerular pressure (decreasing proteinuria). Reduced bradykinin breakdown adds to vasodilation. Its short half-life necessitates frequent dosing.

Formulations and products

• 12.5 / 25 mg tablet
• 50 mg tablet
• Capoten / Angiopril — 12.5 / 25 / 50 mg tablet, Tablet (human-label)

Storage

Tablets: 15–30 °C, dry, protect from light/moisture.

Before you use this dose

Reference doses for veterinary professionals. Confirm the dose against the product label, the patient’s condition, current guidance and local regulations before use; the attending veterinarian remains responsible for every clinical decision.

Other cardiovascular drugs

• Amiodarone
• Amlodipine
• Atenolol
• Benazepril
• Carvedilol
• Digoxin
• Diltiazem
• Dobutamine

Frequently asked questions