Vet Guide to Digoxin (Lanoxin®) in 2025 🐾

Hi, I’m Dr Duncan Houston, BVSc—founder of Ask A Vet. This comprehensive 2025 guide explores digoxin, a cardiac glycoside used off-label in dogs to strengthen heart contractions and regulate heart rate in congestive heart failure (CHF) and arrhythmias. We'll walk through how it works, proper dosing, potential risks, drug interactions, monitoring strategies, and safety practices to support your dog’s heart health. 💖

📘 How Digoxin Works

Digoxin inhibits the cardiac sodium-potassium ATPase pump, boosting intracellular calcium and strengthening heart contractions (positive inotrope). It also slows heart rate by increasing vagal tone and reducing AV nodal conduction—helpful in atrial fibrillation and supraventricular tachycardia :contentReference[oaicite:3]{index=3}.

✅ When It's Used in Dogs

• 📌 **CHF treatment:** Co-administered with diuretics and ACE inhibitors in dogs with valvular disease or dilated cardiomyopathy :contentReference[oaicite:4]{index=4}.
• ❤️ **Rate control:** Helps manage atrial fibrillation or SVT—often paired with diltiazem :contentReference[oaicite:5]{index=5}.
• 👉 Note: Pimobendan is often preferred due to a wider safety margin and proven efficacy :contentReference[oaicite:6]{index=6}.

📐 Dosing & Administration

• **Oral dosing:** ~0.0025–0.005 mg/lb every 12 hours (~0.005–0.010 mg/kg BID) :contentReference[oaicite:7]{index=7}.
• **IV use:** Administered in emergencies under vet supervision :contentReference[oaicite:8]{index=8}.
• Can be given with or without food; food delays absorption but decreases GI upset :contentReference[oaicite:9]{index=9}.
• Always follow **lean body weight** and adjust for kidney function :contentReference[oaicite:10]{index=10}.
• Never double-dose. If a dose is missed, give as soon as possible unless next dose is imminent :contentReference[oaicite:11]{index=11}.

⚠️ Monitoring & Side Effects

Common side effects:

• GI signs—vomiting, diarrhea, anorexia, weight loss; usually mild :contentReference[oaicite:12]{index=12}.
• Fatigue, weakness, lighter activity levels :contentReference[oaicite:13]{index=13}.

Serious toxic effects:

• Arrhythmias, worsened CHF, syncope or collapse :contentReference[oaicite:14]{index=14}.
• Neurological signs like seizure or fainting—may reflect toxicity :contentReference[oaicite:15]{index=15}.
• High sensitivity in dogs with kidney disease—adjust dose and monitor closely :contentReference[oaicite:16]{index=16}.

Lab monitoring needed:

• Serum digoxin levels: check after 5 half-lives (~5–8 days), then every few months or if side effects appear :contentReference[oaicite:17]{index=17}.
• Electrolytes—especially potassium, as imbalance increases toxicity risk :contentReference[oaicite:18]{index=18}.
• Regular ECGs and chest X‑rays to assess heart function :contentReference[oaicite:19]{index=19}.

🔗 Drug Interactions

• **Increases digoxin levels:** amiodarone, diltiazem, erythromycin, itraconazole, spironolactone :contentReference[oaicite:20]{index=20}.
• **Decreases levels:** antacids, cimetidine, metoclopramide—give these 2 hours apart :contentReference[oaicite:21]{index=21}.
• **Additive effects with other heart meds:** beta‑blockers, ACE inhibitors – monitor bradycardia and blood pressure :contentReference[oaicite:22]{index=22}.

⏳ Overdose Response

• Signs: GI distress, arrhythmia, collapse, seizures :contentReference[oaicite:23]{index=23}.
• Treatment: Stop digoxin, therapeutic blood tests, correct electrolytes, consider digoxin-immune Fab in severe cases :contentReference[oaicite:24]{index=24}.
• Activated charcoal for recent oral overdose; IV fluids + anti‑arrhythmic as needed :contentReference[oaicite:25]{index=25}.

🏡 Real‑World Scenarios

🐶 Atrial Fibrillation in a Boxer

• Started digoxin 0.005 mg/kg BID + diltiazem. HR stabilized by Day 5; digoxin level measured at 1.0 ng/mL.
• No GI or neurologic side effects after 3 months of therapy, stable electrolytes and ECG findings.

🐶 Senior CKD + CHF

• Lower dose (0.0025 mg/kg BID) used to avoid toxicity; kidney values monitored monthly.
• Adjustments made based on serum levels and signs—improved appetite and breathing noted.

❓ Frequently Asked Questions

Is digoxin safe long-term?

Yes—if closely monitored. Blood levels and ECGs ensure it stays within a narrow therapeutic window :contentReference[oaicite:26]{index=26}.

Why is pimobendan preferred?

Pimobendan provides stronger inotropic support and vasodilation with fewer side effects; digoxin is reserved when rate control is essential :contentReference[oaicite:27]{index=27}.

Can I give it with food?

Yes—food may reduce GI upset but delays absorption. Consistency is key—always give the same way :contentReference[oaicite:28]{index=28}.

📌 Final Takeaways

• Digoxin is a valuable cardiac glycoside for managing CHF and rate control in dogs—but use requires precision and vigilance.
• Typical dosing is 0.0025–0.005 mg/lb (0.005–0.01 mg/kg) BID, with adjustments based on labs and response.
• Monitor blood levels, electrolytes, ECG, and watch for signs of GI upset or arrhythmias.
• Be aware of drug interactions and adjust treatment with related medications.
• Overdose risk is high—seek emergency care if severe symptoms appear.

Considering digoxin for your dog’s heart condition? Download the Ask A Vet app for precise dosage reminders, blood-test tracking, heart-rate logging, and 24/7 veterinary support—helping your pup live better and longer in 2025 and beyond. 🐾❤️