Ringworm (Dermatophytosis) in Guinea Pigs: Vet Guide 2025 🐹🦠

— Written by Dr Duncan Houston BVSc, founder of Ask A Vet —

1. What Is Ringworm?

Ringworm, or dermatophytosis, is a fungal infection—not a worm. In guinea pigs, it's most often caused by Trichophyton mentagrophytes, sometimes Microsporum canis (PetMD) :contentReference[oaicite:2]{index=2}. The fungus invades the skin’s outer layers, causing localized lesions.

2. Who's at Risk?

• Young, senior, pregnant or immunocompromised guinea pigs
• Overcrowded or unsanitary housing—warm, humid conditions favor fungal growth :contentReference[oaicite:3]{index=3}
• Environmental exposure: contaminated bedding, tools, or contact with infected humans/animals

3. Signs & Symptoms

• Round or irregular bald patches, often on head, face, feet, or trunk :contentReference[oaicite:4]{index=4}
• Redness, crusting, scaling at lesion edges
• Sparse itching—some cases itchy, others mild
• Roughened coat and occasional nail involvement

Pictured lesions often show raised crusts and hairless areas. :contentReference[oaicite:5]{index=5}

4. Zoonotic & Herd Risk

Ringworm spreads easily between piggies and humans. If lesions appear on skin, veterinary and medical advice is essential :contentReference[oaicite:6]{index=6}. All co-housed pets should be considered exposed.

5. Diagnosing Ringworm

• Cytology: pluck hairs and examine under microscope for fungal spores or arthrospores :contentReference[oaicite:7]{index=7}.
• Woods lamp: limited use—often negative in guinea pigs :contentReference[oaicite:8]{index=8}.
• Fungal culture: gold standard; takes 10–21 days :contentReference[oaicite:9]{index=9}.
• Dermatophyte PCR: faster (3–5 days), precise fungal species detection :contentReference[oaicite:10]{index=10}.

6. Treatment Protocols

🐾 Topical Therapy

• Antifungal creams, sprays, or lime-sulfur dips (e.g., miconazole, clotrimazole)
• Apply daily to lesions and margin; continue for at least a week after clinical cure

💊 Oral Medications

• Itraconazole or terbinafine for widespread or deep lesions
• Potential side effects—monitor liver values

⚕️ Supportive Care

• Antibiotics if secondary bacterial infection occurs
• Ensure adequate nutrition, hydration, stress reduction

7. Environmental Decontamination

Eliminate fungal spores by:

• Daily cleaning and weekly deep disinfecting (1:10 bleach, enilconazole, benzalkonium chloride) :contentReference[oaicite:11]{index=11}
• Launder or discard bedding, fleece, toys
• Isolate infected piggies until 2 negative cultures/tests
• Use gloves and wash hands thoroughly after handling

8. Treatment Duration & Follow-up

• Treatment usually continues for 4–8 weeks, or until 2 negative cultures/PCR results
• Reassess if lesions persist, recur, or spread

9. Prognosis

With proper therapy and hygiene, most guinea pigs recover completely—regrowth of fur, skin healing, no lasting issues. Untreated cases may linger or spread to other pets or humans.

10. Prevention

• Quarantine new animals for 30 days and screen for dermatophytes :contentReference[oaicite:12]{index=12}
• Keep housing clean, dry, well-ventilated
• Minimize stress and overcrowding
• Regularly inspect skin and coat during wellness exams

11. Role of Ask A Vet

• 📸 Remote triage: review photos of lesions and advise if vet visit needed
• 💊 Guidance on safe topical/oral antifungals for piggies
• 🏡 Environmental hygiene plan: disinfecting steps, cage management
• 🔂 Treatment tracking—set reminders for medication and cleaning
• 🧭 Timely re-evaluation prompts based on response

12. FAQs

• Can ringworm go away without treatment? Rarely—it usually requires antifungal therapy and cage cleaning.
• Is it dangerous to humans? Yes—ringworm is contagious. Wash hands and wear gloves during care.
• When can they return to group housing? After clinical cure and two negative fungal tests.

📣 Conclusion

Ringworm is treatable but contagious. Quick diagnosis, consistent antifungal treatment, and thorough hygiene are essential to cure and prevent spread. With Ask A Vet's expert guidance, you can keep your guinea pigs and household healthy and rash-free. 🐾

See bald patches or crusting? Contact your exotic vet promptly and use the Ask A Vet app for treatment support and recovery tracking. 📱

— Dr Duncan Houston BVSc, Ask A Vet