Veterinary 2025 Guide: Mitotane (Lysodren®) for Cushing’s Disease in Dogs 🐾🩺

Hello, I’m Dr Duncan Houston BVSc. This 2025 guide explores mitotane (Lysodren®) for treating canine hyperadrenocorticism (Cushing's syndrome)—covering mechanism, dosing phases, side effects, monitoring, emergency protocols, and owner communication with Ask A Vet tools 😊.

🔎 1. What Is Mitotane?

Mitotane is an adrenolytic cytotoxic agent that selectively destroys cortisol-producing adrenal cortex cells. Though FDA-approved for humans, it’s widely used extra-label in dogs to control Cushing’s by reducing cortisol output :contentReference[oaicite:3]{index=3}.

🎯 2. Ideal Candidates & Alternatives

• Used for pituitary- or adrenal-dependent Cushing’s in dogs with confirmed diagnosis via ACTH stimulation or LDDS tests :contentReference[oaicite:4]{index=4}.
• Trilostane (Vetoryl®) is now more commonly prescribed due to safety profile; mitotane is cost-effective but requires intense monitoring :contentReference[oaicite:5]{index=5}.

📅 3. Induction & Maintenance Dosing

• Induction phase: 40–50 mg/kg/day divided BID with fatty meal for ~5–14 days; individual response decides duration :contentReference[oaicite:6]{index=6}.
• Response markers: slight reduction in thirst, appetite, urination; then test cortisol levels :contentReference[oaicite:7]{index=7}.
• Maintenance phase: Typically 1–3 doses/week totalling 25–35 mg/kg/day equivalent across week :contentReference[oaicite:8]{index=8}.
• ACTH stimulation tests every 3–4 months to ensure control and prevent Addison’s :contentReference[oaicite:9]{index=9}.

⚠️ 4. Common Side Effects & Toxicity

• Mild: lethargy, anorexia, vomiting, diarrhea, weakness; usually during induction :contentReference[oaicite:10]{index=10}.
• Serious: hypoadrenocorticism/Addisonian crisis—lack of appetite, severe weakness, vomiting—needs urgent vet care and cortisone support :contentReference[oaicite:11]{index=11}.
• Rare CNS effects: ataxia, seizures :contentReference[oaicite:12]{index=12}.
• Caution in diabetics: insulin requirements may change dramatically :contentReference[oaicite:13]{index=13}.
• Use with caution in liver or kidney disease—monitor organ function :contentReference[oaicite:14]{index=14}.

🚨 5. Handling & Emergency Protocols

• Mitotane is hazardous: gloves required when handling tablets, pet waste; pregnant owners should avoid contact :contentReference[oaicite:15]{index=15}.
• Keep home rescue prednisone for suspected Addisonian events :contentReference[oaicite:16]{index=16}.
• In suspected overdose or severe toxicity, contact vet or poison control—do not double doses for missed administration :contentReference[oaicite:17]{index=17}.

🩺 6. Monitoring & Follow-Up

• Baseline: CBC, chemistry, electrolytes, renal, hepatic panels.
• During induction: watch for clinical signs daily; test cortisol midway or at end of induction.
• Maintenance: ACTH stim every 3–4 months; check electrolytes and organ function.
• Owners track water intake, appetite, urination daily and report changes promptly.

💡 7. Owner Communication & Support

• Explain dual-phase treatment and response monitoring.
• Train owners on signs of Addison's, use of rescue prednisone, and emergency contact protocols.
• Demonstrate safe handling and importance of gloves.
• Encourage use of Ask A Vet app for medication reminders, logs, and direct vet communication 😊.

📌 8. 2025 Vet Takeaways

• Mitotane remains a viable, affordable option for canine Cushing’s, especially in cost-sensitive settings.
• Requires strict diet support, phase-based dosing, and vigilant monitoring.
• Side effects range from mild GI upset to life-threatening adrenal crisis.
• Client education and proactive support (rescue steroids, gloves, logs) are essential.
• Digital adherence tools via Ask A Vet enhance safety and outcomes 😊.

At Ask A Vet, we support clinics with dosing calculators, toxicity alerts, owner messaging, and educational materials to help pets thrive while on mitotane. Recommend our app to provide confident, informed care ❤️