Pigeon fever is a contagious disease in horses caused by a hardy bacteria that lives in soil, Corynebacterium pseudotuberculosis. The bacteria and can enter the body through small cuts or scrapes, often carried by flies. It most commonly causes large abscesses on the chest or belly, but in some cases it can affect the limbs or even internal organs, leading to more serious illness. The bacteria can survive in the environment for long periods, and cases tend to increase during warm months when flies are most active.
This disease is important for horse owners to recognize because it spreads easily and can take weeks to months for affected horses to recover. In Oregon, pigeon fever is immediately reportable, and sick horses should be isolated to prevent infecting others. Good fly control, regular sanitation, and prompt veterinary attention help protect the health of both individual horses and the larger herd.
Clinical Signs
Pigeon fever can cause several types of inflammation and swelling depending on the form of the disease. Three disease forms occur, each with distinct clinical signs:
- External abscesses (most common):
- Single or multiple abscesses, commonly on the chest or belly
- Tan, odor‑free pus
- Most horses are not systemically ill
- Internal abscesses (occurs in about 8% of cases):
- Organs affected may include liver, kidneys, spleen, and lungs; septic arthritis and osteomyelitis have been reported
- Fever, lethargy; often appear 1–2 months after peak season
- May occur alongside external abscesses
- Can cause severe, sometimes fatal disease
- Ulcerative lymphangitis (least common form):
- Severe limb swelling, cellulitis, multiple draining tracts, marked lameness, fever, lethargy
- Laminitis may develop due to increased weight‑bearing on unaffected limbs
Prevention & Biosecurity
To protect horses from pigeon fever, owners should focus on minimizing exposure to insects and environmental contamination. The following actions are important for disease prevention and control:
- Control flies around barns, manure areas, and paddocks
- Use fly sprays, masks, and protective sheets
- Keep stalls and turnout areas clean and dry
- Avoid sharing euqipment (tack, buckets, grooming tools) between horses, especially if sores or drainage are present
- Quarantine new arrivals to reduce disease introduction
- Isolate any horse with significant limb swelling, abscesses, or draining tracts immediatley until evaluated by a veterinarian
- Wear gloves and protective clothing when handling affected horses
- Clean and disinfect areas contaminated with draining abscess material
The bacteria can survive in soil for up to eight months and for a couple of months in hay and shavings.
If you suspect pigeon fever, report it immediately:
Contact your veterinarian.
Recommendations & Treatment
Your veterinarian can help diagnose pigeon fever, sometimes by clinical signs and sometimes by taking samples from abscesses and submitting to a laboratory for testing (culture or PCR).
Your veterinarian also will be able to provide guidance on supportive care and biosecurity.
- Abscesses are typically lanced and flushed when mature
- Many external abscesses do not require antibiotics; treatment depends on location and severity
- Internal abscesses require intensive veterinary management
- Isolate affected horses to prevent spread
Resources
ODA Resources
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Pigeon Fever
For Oregon pigeon fever cases and outbreak information, see the main pigeon fever webpage.
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