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Spironolactone

Prescription
Potassium-sparing diuretic / Aldosterone antagonist
Last reviewed 19 Apr 2026 · PetCare.AI Editorial Team
Species
Dog, Cat
Brands
3 available
Interactions
11 documented
Formulations
3

Mechanism of action

Competitively blocks aldosterone receptors in the distal tubule, promoting sodium and water excretion while retaining potassium; also has anti-fibrotic cardiac effects

At a glance

Class
Potassium-sparing diuretic / Aldosterone antagonist
Schedule
Prescription
Storage
Store below 25°C, protect from light and moisture

Dosing

🐕

Dog

Congestive heart failure (adjunct)
Dose
0.5–2 mg/kg
Route
PO
Frequency
BID
Max dose
40 mg/dose; 80 mg/day
Duration: Long-term
🐈

Cat

Congestive heart failure (adjunct)
Dose
1–2 mg/kg
Route
PO
Frequency
BID
Max dose
12.5 mg/dose; 25 mg/day
Duration: Long-term
Educational reference only
This information is provided for educational purposes and is not a substitute for professional veterinary advice, diagnosis, or treatment. Always consult a qualified veterinarian before administering any medication to your pet. Find a vet near you →

Formulations

💊

Tablet — 3

Strength
10mg
Available in India
Strength
25mg
Available in India
Strength
50mg
Available in India

Storage

Store below 25°C, protect from light and moisture

Safety

Absolute contraindications — do not use

  • Hyperkalemia
  • Addison's disease (hypoadrenocorticism)

Use with caution

  • Concurrent ACE inhibitors
    Monitor potassium closely

Adverse effects

Common
GI upset
Facial dermatitis (cats)
Serious
Hyperkalemia
Dehydration
Electrolyte imbalances

Monitoring parameters

Serum potassiumRenal valuesElectrolytesHydration status
Educational reference only
This information is provided for educational purposes and is not a substitute for professional veterinary advice, diagnosis, or treatment. Always consult a qualified veterinarian before administering any medication to your pet. Find a vet near you →

Interactions

Major — 7

Trilostane
major
Trilostane reduces cortisol; spironolactone is an aldosterone antagonist. Combined adrenal suppression risks Addisonian crisis.
Management: Avoid concurrent use unless under specialist supervision with frequent ACTH stimulation testing.
Losartan
major
Both cause potassium retention; combined use significantly increases hyperkalemia risk
Management: Monitor serum potassium frequently. Consider alternative diuretic if ARB is required.
Mitotane (o,p'-DDD)
major
Mitotane destroys adrenal cortex. Spironolactone blocks remaining aldosterone activity. Combined: severe mineralocorticoid deficiency (hyperkalemia, hyponatremia, hypotension).
Management: Avoid. If diuretic needed during mitotane therapy, use furosemide (not potassium-sparing diuretic).
Potassium Citrate
major
Spironolactone (potassium-sparing diuretic) + potassium supplementation: high risk of dangerous hyperkalemia.
Management: Avoid concurrent potassium supplementation. If potassium needed, monitor levels every 3-5 days. Discontinue supplement if K+ >5.5 mEq/L.
Telmisartan
major
ARB (reduces aldosterone) + aldosterone antagonist (spironolactone): additive potassium retention. High hyperkalemia risk.
Management: Monitor potassium closely if combining. Avoid concurrent potassium supplements.
Irbesartan
major
ARB + potassium-sparing diuretic: additive potassium retention causing hyperkalemia.
Management: Monitor potassium closely. Avoid concurrent potassium supplements.
Desoxycorticosterone Pivalate (DOCP)
major
DOCP replaces aldosterone in Addison's disease. Spironolactone blocks aldosterone receptors, directly antagonizing DOCP's mineralocorticoid effect — causes hyperkalemia and sodium loss.
Management: NEVER combine. Spironolactone would negate DOCP treatment for Addison's disease.

Moderate — 4

Benazepril
moderate
Both cause potassium retention; combined use increases risk of life-threatening hyperkalemia
Management: Monitor serum potassium closely if used together. Common cardiac combination but requires monitoring.
Digoxin
moderate
Spironolactone can increase digoxin levels by reducing renal clearance
Management: Monitor digoxin levels when adding spironolactone. May need digoxin dose reduction.
Enalapril
moderate
Dual RAAS blockade with additive potassium retention. Clinically used in heart failure but requires monitoring.
Management: Standard heart failure combination — monitor potassium at 3-5 days and regularly thereafter. Avoid concurrent potassium supplementation.
Meloxicam
moderate
NSAIDs reduce renal prostaglandin-mediated potassium excretion, additive to spironolactone's potassium retention. Also reduces diuretic efficacy.
Management: Monitor potassium and renal function. Ensure hydration.
Educational reference only
This information is provided for educational purposes and is not a substitute for professional veterinary advice, diagnosis, or treatment. Always consult a qualified veterinarian before administering any medication to your pet. Find a vet near you →

Brands

International

Prilactone
Vetoquinol

India

Aldactone
RPG Life Sciences
Spiromide
Mankind

FAQs

Frequently asked questions

What is Spironolactone?
Spironolactone is a potassium-sparing diuretic / aldosterone antagonist used in pets. Competitively blocks aldosterone receptors in the distal tubule, promoting sodium and water excretion while retaining potassium; also has anti-fibrotic cardiac effects
What is Spironolactone used for in pets?
Spironolactone is used in veterinary medicine for: Congestive heart failure (adjunct).
What is the Spironolactone dose for dogs?
For dogs, Spironolactone is typically dosed as follows — Congestive heart failure (adjunct): 0.5–2 mg/kg PO BID. Always consult your veterinarian for a dose tailored to your pet's weight, age, and condition.
What is the Spironolactone dose for cats?
For cats, Spironolactone is typically dosed as follows — Congestive heart failure (adjunct): 1–2 mg/kg PO BID. Always consult your veterinarian for a dose tailored to your pet's weight, age, and condition.
What are the side effects of Spironolactone?
Common: GI upset, Facial dermatitis (cats). Serious (call your vet immediately): Hyperkalemia, Dehydration, Electrolyte imbalances.
Does Spironolactone need a prescription?
Yes. Spironolactone is a prescription medication and should only be administered under veterinary supervision.
When should Spironolactone not be used?
Do not use Spironolactone if: Hyperkalemia; Addison's disease (hypoadrenocorticism).
Educational reference only
This information is provided for educational purposes and is not a substitute for professional veterinary advice, diagnosis, or treatment. Always consult a qualified veterinarian before administering any medication to your pet. Find a vet near you →

References

References

The PetCare.AI drug reference is built from 13 authoritative sources cited across 580 drug monographs.

Textbooks & handbooks — 5

  • Plumb's Veterinary Drug Handbook
  • Withrow & MacEwen's Small Animal Clinical Oncology
  • Merck Veterinary Manual
  • NRC Nutrient Requirements of Dogs and Cats
  • Veterinary Pharmacology and Therapeutics (Riviere & Papich)

Clinical guidelines & consensus — 4

  • ASPCA Animal Poison Control Center Guidelines
  • AAHA Diabetes Management Guidelines
  • ASPCA Poison Control Guidelines
  • RECOVER CPR Guidelines

Journals & peer-reviewed studies — 2

  • EPIC Study (J Vet Intern Med 2016)
  • JVIM FAT CAT Study

Regulatory & approvals — 1

  • CDSCO Veterinary Drug Approval Registry (1969–2026)

Databases — 1

  • Washington State University VCPL MDR1 Database
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