🧬 Mycobacteriosis in Amphibians: A Vet’s 2025 Guide to Diagnosis, Treatment & Prevention | Dr Duncan Houston BVSc

Mycobacteriosis, also called “myco” or “tuberculosis,” is a bacterial infection in amphibians caused by species in the genus Mycobacterium. It’s difficult to treat, often fatal — and zoonotic, meaning it can infect humans. 🐸⚠️

🧫 What Is Mycobacteriosis?

This disease occurs when atypical Mycobacteria like M. marinum, M. avium, M. fortuitum, or M. xenopi invade the amphibian’s tissues. These bacteria can form granulomas (lumps) or ulcers and can affect the lungs, skin, GI tract, heart, and spleen. 🦠

Zoonotic Alert:

• 👤 M. marinum is known to infect humans via open wounds
• 🧼 Wear gloves when handling any amphibian showing signs

🧠 How It Appears in Frogs

• ⚪ Non-healing ulcers, often on toes or feet
• 🧱 White, tan, or gray nodules under skin (granulomas)
• 🍽️ Weight loss despite appetite
• 📉 Lethargy, hiding, or weakness
• 🩺 Systemic illness: GI, respiratory, or liver dysfunction

The disease is more common in adults and frogs kept in poor conditions, especially aquatic environments with inadequate sanitation. 🌊

🧬 Affected Species

All amphibians are vulnerable, but highest risk is seen in:

• 🦶 Xenopus spp. (African clawed frogs)
• 🐸 Tree frogs, dart frogs, and other aquatic species

Immune-compromised frogs and those with skin abrasions are most at risk. 🧪

🔍 Diagnosis

Diagnosis starts with a vet visit for history, physical exam, and visual inspection for nodules or ulcers. Further testing includes:

• 🔦 Transillumination (to see internal nodules)
• 🧪 Bloodwork: Elevated white blood cells
• 📸 X-rays or imaging (if internal granulomas are suspected)
• 🔬 Biopsy with acid-fast stain (confirms mycobacteria)
• 🧬 PCR for species-level ID & culture to determine antibiotics

Species ID is essential due to differences in zoonotic risk and antibiotic resistance. 📋

💊 Treatment

🚨 Treatment Warning:

If the identified species is high-risk for humans (e.g., M. avium), your vet may recommend euthanasia. ❌

If treatment proceeds, be prepared for:

• 💊 Multiple antibiotics (at least 6–12 months)
• 💰 Significant cost
• 🧼 Strict biosecurity
• 💉 Repeat biopsies to confirm recovery

Improvements in husbandry (heat, humidity, diet) are crucial to support the immune system. 💪

Common Medications:

• 🧪 Combination antibiotic protocols — based on culture
• 🛁 Soaking and hydration support
• 🧃 Nutritional support via syringe feeding
• 💊 NSAIDs (e.g., meloxicam) for pain and inflammation

📈 Prognosis

• ⚠️ Guarded to poor overall
• 📉 90% of diagnosed cases die within 3 months
• ✅ Early detection + species-appropriate therapy = better odds

Amphibians that improve should be rechecked regularly for recurrence. 🧪📆

🛡️ Prevention

1. Quarantine

• 📦 Isolate new amphibians for 180+ days
• 🔬 Monitor for skin ulcers or granulomas

2. Sanitation

• 🧴 Use disinfectants with mycobactericidal activity
• 🧤 Change gloves between enclosures
• 🧽 Clean tools between cages

3. Husbandry

• 🌡️ Provide appropriate temps and humidity
• 🛏️ Use smooth, cleanable surfaces in habitats
• 🧪 Maintain biofiltration and water quality

4. Diet

• 🍽️ Feed a balanced, species-appropriate diet
• 🥬 Avoid vitamin A and D deficiencies

📱 AskAVet.com for Risk & Recovery Help

Need help diagnosing skin nodules or managing amphibian biosecurity? Download the Ask A Vet app to connect with amphibian-experienced vets, discuss zoonotic risks, and build a treatment or prevention plan. 🐾💬

Mycobacteriosis is challenging, but with informed decisions, early diagnosis, and proactive care, your frog has a fighting chance. 🐸💚