🦠 Vet Alert 2025: Identifying and Treating Pythiosis in Horses for Early, Life-Saving Care 🐴💉

Author: Dr Duncan Houston, BVSc

Pythiosis—also known as phycomycosis—is a rare but extremely aggressive skin disease that primarily affects horses in warm, wet climates like the Gulf Coast states. While uncommon, it’s devastating when missed or misdiagnosed. In this 2025 veterinary update, Dr Duncan Houston breaks down how to detect, diagnose, and treat this dangerous condition before it's too late. 🐎🚨

🔍 What Is Pythiosis?

Pythiosis is a skin disease caused not by true fungi, but by Pythium insidiosum, a plant-like organism known as an oomycete. These water-borne pathogens thrive in stagnant water, wet grass, and humid environments. 🌿💧

Infection typically occurs when a horse has a small cut or scrape that is exposed to contaminated water or vegetation, allowing the organism to invade the skin. 🧬

📍 Where Lesions Occur

The most common areas affected include:

• 🦵 Legs
• 🐴 Underbelly
• 🌊 Areas exposed to wet, marshy environments

⚠️ Symptoms: What to Watch For

Pythiosis lesions are severe and progress rapidly. Key signs include:

• 🩸 Draining wounds with pus and bloody fluid
• 🧱 Presence of kunkers—small, hard, calcified nodules inside the lesion
• 🔥 Pain, inflammation, and fast expansion of the wound
• 🚫 Lack of response to standard wound treatment

Note: Pythiosis can look like other infections, making veterinary diagnosis essential. A biopsy or tissue culture confirms the diagnosis. 🧪

🔬 Diagnosis and Testing

Due to its similarity to bacterial or fungal infections, a vet will typically:

• 🔬 Perform a tissue biopsy to identify the organism
• 🧫 Send tissue to specialized labs (e.g., Pan American Veterinary Labs) for analysis

Never attempt to self-diagnose or delay veterinary care—early detection is key to survival. 🕵️‍♂️

🛠️ Treatment Options in 2025

1️⃣ Surgical Removal

If caught early, the infected lesion may be surgically removed. However:

• ✂️ Lesions may recur even after removal
• 🩹 Multiple surgeries may be needed

2️⃣ Vaccine Therapy

A pythiosis-specific vaccine from Pan American Veterinary Labs is available and shows good success in early and even some chronic cases. 💉

• ⚠️ Most effective before lesions become large or systemic
• 💪 Can reduce lesion size and inflammation when used correctly

3️⃣ Supportive Care

Includes wound cleaning, anti-inflammatory medication, and pain management. Antifungals are generally ineffective because Pythium is not a fungus. ❌🍄

🚫 What Doesn’t Work

• ❌ Traditional antifungal medications
• ❌ Delayed veterinary intervention
• ❌ Home remedies or general wound ointments

📉 Consequences of Untreated Pythiosis

• 📈 Rapid lesion expansion
• 🧱 Severe scarring and tissue loss
• 💔 In advanced cases, euthanasia may be necessary

🧠 Expert Advice from Dr Duncan Houston

“If you notice a lesion that’s not healing, especially after exposure to swampy areas, don’t wait. Pythiosis is one of the few conditions where every day counts.” 🐴⏱️

🌿 Prevention Tips

• 🌊 Avoid turnout in stagnant water or wet, marshy pastures
• 🧼 Keep skin clean and dry, especially after exposure to water
• 👀 Monitor for any rapidly growing or unhealing wounds

🧬 Summary: Be Proactive, Act Fast

Pythiosis may be rare, but it's deadly when ignored. Early detection, quick surgical response, and proper use of the pythiosis vaccine are your best defense. Don’t let a minor wound become a major tragedy—know the signs and work with your veterinarian right away. 🩺🐎

Worried about a suspicious lesion on your horse? Visit AskAVet.com or download the Ask A Vet app to connect with a licensed vet anytime. Fast advice could save your horse’s life. 📱🦠