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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

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

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.

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).

References

References

Textbooks & handbooks

  • Plumb, D.C. Plumb's Veterinary Drug Handbook. 10th ed., Wiley-Blackwell, 2023.
  • Vail, D.M., Thamm, D.H., & Liptak, J.M. (eds.). Withrow & MacEwen's Small Animal Clinical Oncology. 6th ed., Saunders/Elsevier, 2020.
  • Riviere, J.E., & Papich, M.G. (eds.). Veterinary Pharmacology and Therapeutics. 10th ed., Wiley-Blackwell, 2018.
  • National Research Council. Nutrient Requirements of Dogs and Cats. National Academies Press, Washington DC, 2006.
  • The Merck Veterinary Manual. Merck & Co., Online edition. https://www.merckvetmanual.com/

Clinical guidelines & consensus

  • Fletcher, D.J., Boller, M., Brainard, B.M., et al. "RECOVER Evidence and Knowledge Gap Analysis on Veterinary CPR." Journal of Veterinary Emergency and Critical Care, 2012;22(S1):S102–S131.
  • American Animal Hospital Association. 2018 AAHA Diabetes Management Guidelines for Dogs and Cats. AAHA Press.

Journals & peer-reviewed studies

  • Hogan, D.F., Fox, P.R., Jacob, K., et al. "Secondary prevention of cardiogenic arterial thromboembolism in the cat: The FAT CAT study." Journal of Veterinary Cardiology, 2015;17(Suppl 1):S306–S317.
  • Boswood, A., Häggström, J., Gordon, S.G., et al. "Effect of Pimobendan in Dogs with Preclinical Myxomatous Mitral Valve Disease and Cardiomegaly: The EPIC Study — A Randomized Clinical Trial." Journal of Veterinary Internal Medicine, 2016;30(6):1765–1779.
  • ASPCA Animal Poison Control Center. Toxicology and Poison Management Guidelines. American Society for the Prevention of Cruelty to Animals. https://www.aspca.org/pet-care/animal-poison-control

Regulatory & approvals

  • Central Drugs Standard Control Organisation (CDSCO), Government of India. Veterinary Drug Approval Registry, 1969–2026. Directorate General of Health Services. https://cdsco.gov.in/

Databases

  • Washington State University, College of Veterinary Medicine. Veterinary Clinical Pharmacology Laboratory (VCPL) — MDR1 Multidrug Sensitivity Database. https://vcpl.vetmed.wsu.edu/
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 →