🍄 Antifungal

Ketoconazole for Dogs Dosage Calculator

Veterinary ketoconazole dosing for dogs — covering systemic fungal infections, Malassezia dermatitis, and off-label Cushing’s disease management with tablet breakdown and hepatotoxicity monitoring guidance.

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Hepatotoxicity risk — monitor liver enzymes. Ketoconazole inhibits hepatic CYP450 enzymes and can cause hepatotoxicity. Obtain baseline ALT/ALP before treatment; recheck every 2–4 weeks during therapy. Give with food to improve bioavailability and reduce GI upset.

What Is Ketoconazole for Dogs?

Ketoconazole is an imidazole antifungal that inhibits fungal lanosterol 14α-demethylase (CYP51), blocking ergosterol synthesis and disrupting fungal cell membrane integrity. In dogs it is used for systemic mycoses (blastomycosis, histoplasmosis, coccidioidomycosis, cryptococcosis), Malassezia dermatitis and otitis, and off-label for hyperadrenocorticism (Cushing’s disease) by inhibiting adrenal steroidogenesis.

Ketoconazole requires gastric acid for dissolution and absorption — give with food. Bioavailability varies significantly; patients on antacids or PPIs may have reduced absorption. It is available as 200 mg tablets.

Indications and Dose Ranges

  • Systemic fungal infections: 5–10 mg/kg PO q12–24h (duration by infection type)
  • Malassezia dermatitis: 5–10 mg/kg PO q24h × 3–4 weeks
  • Cushing’s disease (off-label): 15 mg/kg PO q12h — titrate to effect, monitor cortisol
  • Steroidogenesis inhibition (adjunct): 5–15 mg/kg q12h

How to Use This Calculator

  1. Enter your dog’s weight in kg or lbs
  2. Select the indication to apply the correct dose range
  3. Click Calculate to see dose per administration and tablet count
  4. Always give with food; obtain baseline liver panel

🧮 Ketoconazole Dose Calculator

Ketoconazole Dosing Result

Drug Interactions

  • Cyclosporine: Ketoconazole significantly increases cyclosporine levels — major interaction, dose reduction needed
  • Antacids / PPIs / H2 blockers: Reduce ketoconazole absorption — separate by 2 hours
  • Phenobarbital / rifampicin: Reduce ketoconazole plasma levels
  • Warfarin / anticoagulants: Increased anticoagulant effect — monitor clotting times
  • Cisapride / certain antiarrhythmics: QT prolongation risk — avoid combination

References

  1. Plumb DC. Plumb’s Veterinary Drug Handbook, 9th ed. Wiley-Blackwell; 2018.
  2. Papich MG. Saunders Handbook of Veterinary Drugs, 4th ed. Elsevier; 2016.
  3. Bruyette DS. Hyperadrenocorticism in dogs. In: Ettinger SJ, ed. Textbook of Veterinary Internal Medicine. 7th ed. Saunders; 2010.
  4. Moriello KA. Dermatophytosis in dogs. Vet Clin North Am Small Anim Pract. 2004;34(2):411-429.