🧬 Vet Guide 2025: Decoding Equine Skin Disease—From Ringworm to Allergies and Lice 🐴🧴

Author: Dr Duncan Houston, BVSc

Horse owners often encounter mysterious bumps, scabs, or patches of hair loss on their horse’s skin. While many skin issues appear similar to the naked eye, they can stem from drastically different causes—each requiring its own treatment. In this comprehensive 2025 vet guide, Dr Duncan Houston helps horse owners recognize and respond to common skin conditions like ringworm, bacterial infections, allergies, and lice. 🐎🔬

🔍 Recognizing Skin Disease in Horses

Whether your horse has raised bumps, hairless areas, or itchy lesions, it's important to look beyond appearances. Skin reactions can be due to:

• 🦠 Fungal infections (e.g., ringworm)
• 🧫 Bacterial infections (e.g., Staph or MRSA)
• 🦟 Allergic reactions to insects or environment
• 🪳 Parasites like lice

Without proper diagnosis, treating skin lesions blindly can be ineffective—or even harmful. 🔬

🦠 Ringworm: The Fungal Mimic

Ringworm is a highly contagious fungal infection—not a worm. It spreads through direct contact or contaminated items like grooming tools and tack. 😷

🩺 Symptoms:

• 🔘 Round, crusty hairless patches (often on the neck)
• 🐾 Mild itching and rubbing
• 🧬 May resemble other skin conditions like Staph infections

🧪 Diagnosis:

• 📦 Fungal culture from hair/flakes at lesion edge (takes up to 2 weeks)
• ⚡ New PCR tests are faster (2–3 days), but not fully validated in horses yet

🧴 Treatment:

• 🧼 Antifungal shampoos (e.g., miconazole, ketoconazole)
• 🟡 Lime sulfur dips for widespread cases
• 🚫 Avoid corticosteroids before confirming it’s not ringworm

🧫 Bacterial Skin Infections (Including MRSA)

Bacterial infections—especially those caused by Staphylococcus—are common, especially after trauma or insect bites. Resistant forms like MRSA are increasingly seen. 🧪

🩺 Symptoms:

• 🔴 Swollen, red lesions or pustules
• 💥 May ooze pus or serum
• 🧱 Can be painful to the touch

🧪 Diagnosis:

• 🧫 Bacterial culture to identify pathogen and resistance

💊 Treatment:

• 🧴 Topical and oral antibiotics based on culture
• 🧼 Keep lesions clean and dry
• ⚠️ Persistent lesions must be tested for resistant strains

🦟 Allergies: Insects and Environment

Allergies are another common cause of raised skin bumps, swelling, and itching. Horses can react to:

• 🦟 Culicoides midges (saliva triggers intense reactions)
• 🌿 Environmental allergens like dust, pollen, and mold
• 🧴 Contact allergens such as chemicals or shampoos

🩺 Symptoms:

• 📍 Raised, fluid-filled bumps
• 🐴 Scratching and rubbing
• 🧬 Secondary infections from skin trauma

🛠️ Management:

• 🦟 Fly protection gear and repellents
• 💊 Antihistamines or corticosteroids in severe cases
• 🧪 Allergy testing for chronic cases

🪳 Lice: A Winter Worry

Lice infestations often spike during winter and can mimic other skin issues. These visible parasites cause intense itching and discomfort. 🐴

🩺 Signs of Lice:

• 🪳 Visible parasites or eggs on hair shaft
• 🐾 Intense itching and hair loss
• 🧼 Often mistaken for bacterial or fungal infection

🧪 Diagnosis:

• 🔍 Use a lice comb and inspect with magnifying glass or microscope
• ⚠️ Easier to find after exercise (lice move to hair tips)

🧴 Treatment:

• 💧 Insecticidal shampoos and sprays
• 🔁 Repeat treatment in 7–10 days to kill hatching eggs
• 🧹 Disinfect blankets, brushes, and stalls

❌ What Not to Do

• ❌ Don’t rely on unverified over-the-counter products
• ❌ Avoid corticosteroids without ruling out ringworm
• ❌ Don’t guess—get a vet diagnosis before starting treatment

🧠 Dr Duncan Houston’s Takeaway

“Skin issues are tricky because they all look similar. The key is diagnosing correctly before treating—guesswork wastes time and risks your horse’s health.” 🐴🧪

✅ When to Call Your Vet

• ⏱️ Lesions last more than a few days
• ⚠️ Sudden or widespread hair loss
• 🧪 No improvement with initial care
• 📈 Rapidly growing lesions or swelling

🔚 Final Thoughts: Diagnose First, Treat Right

With so many skin conditions sharing similar symptoms, the most important step is getting a correct diagnosis. A quick fungal test or bacterial culture can make all the difference in treatment success. 🩺🐎

Need help identifying a tricky skin condition? Visit AskAVet.com or download the Ask A Vet app for real-time guidance from licensed veterinarians. Your horse’s comfort starts with clarity. 📱🧴