# Captopril: veterinary dose and monograph

> Captopril is a veterinary cardiovascular drug. The first ACE inhibitor — a SHORT-acting agent for congestive heart failure and hypertension. Indications include congestive heart failure (with diuretics ± pimobendan); systemic hypertension; proteinuric kidney disease (reduces proteinuria). This monograph lists 2 reference doses for dogs and cats, each with route, frequency and source.

Source: https://vetmasterji.com/drugs/captopril · Last reviewed: 2026-10-01

## 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- Afterload reduction (largely superseded by longer-acting ACE inhibitors)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

*Captopril doses for dogs*

| Indication | Dose | Route | Frequency | Duration |
| --- | --- | --- | --- | --- |
| CHF / hypertension | 0.5–2 mg/kg | PO | q8–12h | — |

- 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

*Captopril doses for cats*

| Indication | Dose | Route | Frequency | Duration |
| --- | --- | --- | --- | --- |
| Hypertension / CHF | 0.55–1.54 mg/kg | PO | q8–12h | — |

- 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

> **Caution:** 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](https://vetmasterji.com/drugs/amiodarone)
- [Amlodipine](https://vetmasterji.com/drugs/amlodipine)
- [Atenolol](https://vetmasterji.com/drugs/atenolol)
- [Benazepril](https://vetmasterji.com/drugs/benazepril)
- [Carvedilol](https://vetmasterji.com/drugs/carvedilol)
- [Digoxin](https://vetmasterji.com/drugs/digoxin)
- [Diltiazem](https://vetmasterji.com/drugs/diltiazem)
- [Dobutamine](https://vetmasterji.com/drugs/dobutamine)

## Frequently asked questions

### What is the dose of Captopril for dogs?

Reference doses for Captopril in dogs: 0.5–2 mg/kg PO q8–12h (CHF / hypertension). Confirm against the label and the patient before use.

### What is the dose of Captopril for cats?

Reference doses for Captopril in cats: 0.55–1.54 mg/kg PO q8–12h (Hypertension / CHF). Confirm against the label and the patient before use.

### When should Captopril not be used?

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.

### What are the side effects of Captopril in animals?

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

## Sources

- Plumb's Veterinary Drug Handbook
- Merck Veterinary Manual, 11th edition
- Papich, Papich Handbook of Veterinary Drugs, 5th edition

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VetMasterJi is a clinical decision-support and education platform for veterinary professionals and students. It does not provide veterinary advice, diagnosis or treatment for specific animals. All drug doses, calculators and differentials are references that must be independently verified before clinical use; the attending registered veterinarian remains solely responsible for every clinical decision.