Vet Guide 2025: Fungal Diseases in Reptiles & Amphibians 🍄 by Dr Duncan Houston 🩺

Hello! I’m Dr Duncan Houston, BVSc and Ask A Vet founder. Fungal infections—ranging from surface skin issues to deep respiratory or systemic disease—are increasingly recognized threats to reptiles and amphibians in 2025. From “yellow fungus” and Snake Fungal Disease in snakes to shell lesions and chytridiomycosis in aquatics, this comprehensive guide explores causes, clinical signs, diagnostics, antifungal therapies, environmental corrections, and prevention to safeguard your exotic pets’ health.

1. What Are Fungal Diseases?

Reptiles and amphibians can suffer from various mycoses. Skin‑deep infections are common, but fungi also invade respiratory tracts, shells, and internal organs. These often occur opportunistically following injury, antibiotic use, or husbandry stress :contentReference[oaicite:2]{index=2}.

2. Common Fungal Conditions

• Snake Fungal Disease (ophidiomycosis): caused by *Ophidiomyces ophiodiicola*, signs include crusty or ulcerated scales, nodules, facial swelling, pneumonia in severe cases :contentReference[oaicite:3]{index=3}.
• Yellow Fungus Disease: infection by *Nannizziopsis* spp. or related fungi causes yellow‑brown crusting dermatitis in lizards (eg. bearded dragons) :contentReference[oaicite:4]{index=4}.
• Dermatophytosis: ringworm from *Microsporum* or *Trichophyton* may appear in various reptiles, with red scaly patches and occasional alopecia :contentReference[oaicite:5]{index=5}.
• Shell Mycoses: mixed bacterial-fungal infections in turtles/tortoises lead to slow‑healing ulcers on shell plates :contentReference[oaicite:6]{index=6}.
• Chytridiomycosis: fungal disease of amphibians by *Batrachochytrium sp.*, causing sloughing, lethargy, abnormal posture :contentReference[oaicite:7]{index=7}.
• Deep/Systemic Mycoses: rare but severe infections (e.g., phaeohyphomycosis, Basidiobolus) can affect eyes, lungs, muscles or GI tract :contentReference[oaicite:8]{index=8}.

3. Risk Factors & Why They Occur

• High humidity, low temperatures, suboptimal substrate, antibiotic use, trauma, or immunosuppression :contentReference[oaicite:9]{index=9}.
• Overcrowding or shared environments increase fungal exposure, especially for snakes :contentReference[oaicite:10]{index=10}.
• Wounds or shell fractures create entry points. Vitamin or nutritional deficiencies exacerbate immune weakness.

4. Clinical Signs to Recognize

• Skin: crusting, nodules, discolouration, ulceration, retained sheds, facial swelling in snakes.
• Shell: pustules, soft spots, plate discoloration in turtles/tortoises.
• Respiratory: open-mouth breathing, wheezing (often in advanced Snake Fungal Disease or systemic mycoses).
• Systemic disease: weight loss, anorexia, lethargy, neurological signs, eye involvement.
• Amphibians: excessive sloughing, skin thickening, lethargy in chytrid cases.

5. Diagnosis & Testing

• Visual & microscopic exam of lesions or slough for fungal hyphae or spores; skin scrapings :contentReference[oaicite:11]{index=11}.
• Culture & PCR: identification of *Ophidiomyces*, *Nannizziopsis*, chytrid fungi :contentReference[oaicite:12]{index=12}.
• Biopsy & histopathology: to confirm deep or systemic infections :contentReference[oaicite:13]{index=13}.
• Imaging (X‑ray/CT): shell lesions or deep-tissue involvement.

6. Treatment Options

6.1 Environmental Adjustments

• Lower humidity and raise ambient temperatures above fungus tolerance (25–30 °C).
• UV exposure where species appropriate contributes to immune support.
• Improve ventilation, clean substrate and disinfect regularly.

6.2 Topical & Surgical Care

• Debridement of crusts or granulomas; shell debridement in chelonians.
• Topical antifungals like miconazole or iodine dips for surface infections.
• Surgical removal may be required for granulomas, deep lesions.

6.3 Systemic Antifungals

• Terbinafine: demonstrated success in captive snakes with ophidiomycosis :contentReference[oaicite:14]{index=14}.
• Itraconazole**, fluconazole**, amphotericin B**, voriconazole**: used for deep systemic or pulmonary fungal infections :contentReference[oaicite:15]{index=15}.
• Duration often exceeds several weeks to months, with repeat cultures.

7. Prognosis & Follow-up

• Surface infections often resolve with local and environmental treatment.
• Snake Fungal Disease and yellow fungus cases have guarded prognosis; early treatment improves outcomes :contentReference[oaicite:16]{index=16}.
• Systemic mycoses require long-term systemic therapy and strict husbandry; mortality is high :contentReference[oaicite:17]{index=17}.
• Chytridiomycosis in amphibians: antifungal baths and heat therapy effective; prognosis varies :contentReference[oaicite:18]{index=18}.

8. Prevention & Minimizing Risk

• Maintain optimal humidity/temperature, regular cleaning, UVB/light cycles.
• Quarantine new arrivals for 60–90 days with skin/fecal swabs.
• Avoid overcrowding or housing different species together.
• Promptly isolate and treat any wounds or abnormal shedding.
• Monitor regularly for early signs, enabling faster intervention.

9. Ask A Vet Support 🩺

Suspect fungal infection—crusts, shell issues, respiratory signs? Submit lesion photos, diagnostic results (culture, PCR), tank setup via Ask A Vet. We’ll advise on antifungal selection (itraconazole dosing, terbinafine implants), topical protocols, environmental adjustments, and rehab timelines. Visit AskAVet.com 📱

10. Final Thoughts

In 2025, fungal diseases pose a growing challenge to reptile and amphibian welfare. With timely diagnostics, appropriate antifungal therapy, environmental correction, and biosecurity, many infections can be controlled or cured. Using Ask A Vet support ensures expert oversight through long-term treatment journeys—helping your exotic companion stay healthy, strong, and thriving. 🩺🌿

— Dr Duncan Houston, BVSc