🛡️ Pigeon Fever in Horses Vet Guide 2025 by Dr Duncan Houston

Welcome to this thorough guide on pigeon fever in horses—also known as dryland distemper—authored by veterinarian Dr Duncan Houston BVSc. Learn how to identify, diagnose, treat, and prevent this bacterial infection, with insights grounded in updated AAEP guidelines and veterinary best practices. 🐎

📘 What Is Pigeon Fever?

Pigeon fever is a bacterial disease caused by Corynebacterium pseudotuberculosis biovar equi. It often results in abscesses, swelling, fever, and in severe cases, internal organ infections or lymphangitis :contentReference[oaicite:3]{index=3}.

The name originates from the classic symptom: a pectoral swelling resembling a “pigeon chest” :contentReference[oaicite:4]{index=4}.

📊 Forms of the Disease

• External abscesses: Seen most commonly on the chest, ventral abdomen, limbs, or head; often painless and slow to develop :contentReference[oaicite:5]{index=5}.
• Internal abscesses: Occur in ~8% of cases—affect organs like liver, lungs, spleen—with a 30–40% case fatality rate :contentReference[oaicite:6]{index=6}.
• Ulcerative lymphangitis: Rarest; involves severe limb swelling, oozing sores, lameness, systemic illness :contentReference[oaicite:7]{index=7}.

🦠 How It Spreads

Bacteria live in soil, manure, hay, and bedding. Transmission occurs through skin breaks—with flies like horn, stable, and house flies acting as mechanical vectors :contentReference[oaicite:8]{index=8}.

It peaks in late summer and autumn, when fly numbers and environmental stress converge :contentReference[oaicite:9]{index=9}.

🩺 Clinical Signs

• Pectoral or ventral abscesses—firm swellings that mature and rupture.
• Fever, lethargy, appetite loss—often with internal or lymphangitic forms.
• Limb swelling with lymph drainage If lymphangitis develops.

Bloodwork may show anemia, high white cell counts, elevated proteins and acute-phase markers :contentReference[oaicite:10]{index=10}.

🔍 Diagnosis

• External abscesses: Diagnosed clinically, can culture pus or PCR for confirmation.
• Internal abscesses: Diagnosed via serial ultrasound, bloodwork, and SHI serology :contentReference[oaicite:11]{index=11}.
• Lymphangitis: Diagnosed clinically—with ultrasound and lab tests to assess severity.

💊 Treatment Protocols

External Abscesses

• Lance and drain mature abscesses—flush daily with antiseptics. Antibiotics often unnecessary :contentReference[oaicite:12]{index=12}.
• Hot packs promote maturation; tetanus vaccination recommended.

Internal Abscesses & Lymphangitis

• Aggressive systemic antibiotics (penicillin, rifampin, followed by TMS) for 4–6 weeks or more :contentReference[oaicite:13]{index=13}.
• Leg wraps, hydrotherapy, anti-inflammatory support; monitor with ultrasound and labs :contentReference[oaicite:14]{index=14}.

🛡️ Herd Biosecurity & Prevention

• Implement strict fly control: use sprays, traps, masks, pasture spraying, and feeding insect growth regulators :contentReference[oaicite:15]{index=15}.
• Isolate affected horses; don’t share equipment; disinfect tack, buckets, and stalls :contentReference[oaicite:16]{index=16}.
• Manage manure routinely and remove bedding contaminated with drainage :contentReference[oaicite:17]{index=17}.
• Cover wounds promptly; apply insect-repellent dressings; use wound disinfectants and bandages :contentReference[oaicite:18]{index=18}.
• Quarantine new arrivals for several weeks; monitor for abscess or swelling :contentReference[oaicite:19]{index=19}.
• Boost immune health via proper nutrition, vitamins (E, zinc, copper, selenium) and gut support :contentReference[oaicite:20]{index=20}.
• For contaminated paddocks, consider removing topsoil or replacing bedding and soil to reduce bacterial load :contentReference[oaicite:21]{index=21}.

📈 Prognosis

• External abscesses carry an excellent prognosis with proper drainage; low fatality (~0.8%) :contentReference[oaicite:22]{index=22}.
• Internal abscesses—much higher risk; early detection and aggressive therapy are critical :contentReference[oaicite:23]{index=23}.
• Lymphangitis outcomes vary; chronic swelling and secondary laminitis are possible :contentReference[oaicite:24]{index=24}.

📋 Owner Action Plan

• Check horses daily for abscesses, swelling, appetite changes.
• Isolate suspicious cases immediately.
• Contact your veterinarian to plan diagnostics and drainage.
• Control flies aggressively around the herd.
• Disinfect shared surfaces and dispose of contaminated bedding.
• Follow follow-up care, antibiotic schedules, ultrasound monitoring.
• Support with balanced nutrition and immune-enhancing supplements.

📊 Summary Table

🔚 Final Thoughts

Pigeon fever presents significant diagnostic and management challenges—but with early detection, prompt drainage, targeted antibiotics, and robust fly control, most horses recover well. Herd-level prevention and strong biosecurity play essential roles in reducing outbreaks.

For tailored protocols, monitoring support, or outbreak management plans, reach out to our **Ask A Vet** team. Download the Ask A Vet app for 24/7 veterinary access, customized treatment guidance, and expert support for your herd’s health. 🌟