Pigeon Fever in Horses: Corynebacterium Infection and Abscesses

Quick Answer
  • Pigeon fever is a bacterial infection caused by Corynebacterium pseudotuberculosis that most often causes external abscesses on the chest or belly, but it can also cause internal abscesses or severe limb swelling called ulcerative lymphangitis.
  • Most horses with uncomplicated external abscesses recover well with drainage, hot packing, pain control, and careful biosecurity. Internal infection is more serious and can carry a 30% to 40% mortality risk.
  • Call your vet promptly for any new chest or ventral swelling, draining tract, fever, weight loss, or unexplained colic. Horses with fever, poor appetite, marked lethargy, or severe lameness need faster workup for deeper infection.
  • Typical 2026 U.S. cost range is about $350-$900 for an uncomplicated farm call, exam, and abscess workup, $800-$2,500 for repeated drainage and follow-up care, and $2,500-$8,000+ if imaging, prolonged antibiotics, or hospitalization are needed for internal abscesses or ulcerative lymphangitis.
Estimated cost: $350–$8,000

What Is Pigeon Fever in Horses?

Pigeon fever is an infection caused by the bacterium Corynebacterium pseudotuberculosis. The name comes from the classic swelling that can form in the pectoral area and make a horse's chest look like a pigeon's breast. Despite the name, pigeons are not involved. The disease is also called dryland distemper or false strangles.

Horses can develop three main forms of disease: external abscesses, internal abscesses, and ulcerative lymphangitis. External abscesses are the most common and often appear on the chest, ventral abdomen, prepuce, mammary area, or other body sites. Internal infection is less common but much more serious because abscesses may form in organs such as the liver, spleen, kidneys, or lungs.

Many horses with external abscesses do well, especially when the infection is recognized early and managed carefully with your vet. Internal disease and ulcerative lymphangitis can be more prolonged, more painful, and more costly to treat. Because the bacteria can spread through drainage, flies, contaminated equipment, and the environment, isolation and hygiene matter from the start.

Symptoms of Pigeon Fever in Horses

  • Firm or soft swelling on the chest or ventral midline
  • Draining abscess with thick tan, odor-free discharge
  • Fever
  • Lethargy or reduced energy
  • Decreased appetite
  • Weight loss
  • Painful limb swelling, especially one or both hind legs
  • Severe lameness
  • Recurrent or unexplained colic signs
  • Poor performance, malaise, or prolonged recovery from illness
  • Rapid breathing or exercise intolerance

A visible chest or belly abscess is the classic sign, but not every horse follows the textbook pattern. Some horses have only fever, poor appetite, weight loss, or vague colic at first. Those signs raise more concern for internal abscesses, especially if they persist for days or weeks.

See your vet promptly if your horse has a new swelling, draining tract, fever, marked lethargy, or limb swelling. See your vet immediately if there is severe lameness, repeated colic, fast breathing, significant weight loss, or a horse that seems systemically ill, because those signs can point to internal infection or ulcerative lymphangitis.

What Causes Pigeon Fever in Horses?

Pigeon fever is caused by Corynebacterium pseudotuberculosis, a bacterium that can live in soil and contaminated organic material. It usually enters through small breaks in the skin or mucous membranes. Flies, especially house flies, stable flies, and horn flies, can act as mechanical vectors and move bacteria from contaminated material to wounds or irritated skin.

Cases are often seasonal, with peaks during dry months and times of heavy fly activity. Abscesses usually form about 3 to 4 weeks after infection, so the swelling you see today may reflect exposure that happened earlier. Horses in endemic regions are at higher risk, but cases have been reported across the United States and in parts of Canada.

This infection is not considered highly contagious in the same way as some respiratory diseases, but it can still spread between horses through drainage, contaminated hands, tack, grooming tools, buckets, and insects. Draining pus is a major source of environmental contamination. That is why isolation, glove use, hand washing, and careful disposal of discharge are so important.

How Is Pigeon Fever in Horses Diagnosed?

Your vet will start with a physical exam and a careful history, including season, travel, fly exposure, and whether other horses on the property have had abscesses. For external abscesses, the most direct way to confirm the diagnosis is usually bacterial culture or PCR of purulent material collected from the lesion.

If your horse has fever, weight loss, poor appetite, recurrent colic, severe lameness, or no obvious external abscess, your vet may recommend a broader workup. This can include bloodwork, serum amyloid A or fibrinogen, ultrasound of the chest or abdomen, and sometimes repeated imaging over time. Internal abscesses can be challenging to find, so diagnosis often relies on combining exam findings, lab changes, imaging, and response to treatment.

A blood test called the SHI test measures antibodies to C. pseudotuberculosis and can help support a diagnosis of internal infection, especially when there is no external abscess to sample. Still, it should not be used alone. A positive result can reflect past exposure or recovery, and early cases may test negative before antibody levels rise.

Treatment Options for Pigeon Fever in Horses

Spectrum of Care means you have options. Here are treatment tiers at different price points.

Budget-Conscious Care

$350–$900
Best for: Horses with a straightforward external abscess, minimal systemic illness, and no signs suggesting internal infection or severe limb involvement.
  • Farm call and physical exam
  • Focused exam of swelling or draining tract
  • Lancing/drainage when appropriate
  • Hot packing or warm compress instructions
  • Basic anti-inflammatory plan from your vet
  • Isolation, fly control, glove use, and drainage cleanup guidance
  • Limited follow-up if the horse stays bright and the abscess is external and uncomplicated
Expected outcome: Often good for uncomplicated external abscesses when drainage and supportive care are started promptly. External cases have a very low reported fatality rate.
Consider: Lower upfront cost, but it may miss deeper abscesses if the horse later develops fever, weight loss, or recurrent swelling. Antibiotics are often not needed for simple external abscesses and may prolong resolution, so treatment decisions should be individualized by your vet.
Most Common

Recommended Standard Treatment

$800–$2,500
Best for: Most horses with confirmed or strongly suspected pigeon fever, especially when abscesses are deep, multiple, slow to mature, or accompanied by fever or reduced appetite.
  • Exam plus culture and/or PCR of abscess material
  • Sedation and controlled drainage if needed
  • Ultrasound to assess depth and guide drainage of deeper abscesses
  • Bloodwork to look for inflammation or signs of internal disease
  • NSAID plan for pain, fever, and inflammation as directed by your vet
  • Targeted antimicrobial plan when indicated for deep intramuscular abscesses, ulcerative lymphangitis, or systemic illness
  • Recheck visits to monitor healing and decide whether more imaging is needed
Expected outcome: Good for many external cases and fair to good for more complicated soft-tissue cases when monitored closely. Earlier workup improves the chance of catching internal disease before the horse declines.
Consider: Higher cost than conservative care and may involve repeated visits. Some horses need several weeks of wound care, bandaging, or medication adjustments before the infection fully settles.

Advanced / Critical Care

$2,500–$8,000
Best for: Horses with internal abscesses, severe ulcerative lymphangitis, marked systemic illness, recurrent colic, major weight loss, or cases not improving with initial treatment.
  • Hospitalization or intensive ambulatory management
  • Serial abdominal or thoracic ultrasound and expanded bloodwork
  • SHI serology interpreted alongside imaging and clinical signs
  • Aggressive antimicrobial therapy for internal abscesses or ulcerative lymphangitis
  • IV or repeated injectable medications when needed
  • Bandaging, hydrotherapy, hand walking, and limb support for ulcerative lymphangitis
  • Monitoring for complications such as laminitis, septic arthritis, osteomyelitis, or organ involvement
Expected outcome: Variable. Internal infection carries a reported 30% to 40% mortality risk, while ulcerative lymphangitis can be prolonged and may relapse. Some horses recover well with sustained treatment and monitoring.
Consider: Most resource-intensive option and may require weeks of treatment, repeated imaging, and strict biosecurity. It offers the most information and support for complex cases, but recovery can still be slow and uncertain.

Cost estimates as of 2026-03. Actual costs vary by location, clinic, and individual case.

Questions to Ask Your Vet About Pigeon Fever in Horses

Bring these questions to your vet appointment to get the most out of your visit.

  1. You can ask your vet whether this looks like an uncomplicated external abscess or if there are signs that make internal infection more likely.
  2. You can ask your vet if the swelling should be ultrasounded before it is opened, especially if it feels deep or is near important structures.
  3. You can ask your vet whether culture, PCR, bloodwork, or an SHI test would help in your horse's case.
  4. You can ask your vet what home wound-care steps are safest, including hot packing, flushing, bandaging, and how to handle drainage.
  5. You can ask your vet whether antibiotics are appropriate here or whether they may slow resolution of a simple external abscess.
  6. You can ask your vet what warning signs mean your horse needs a recheck right away, such as fever, weight loss, colic, or worsening lameness.
  7. You can ask your vet how to isolate your horse and protect stablemates through fly control, equipment separation, and manure management.
  8. You can ask your vet whether your horse's tetanus vaccination status should be updated during treatment.

How to Prevent Pigeon Fever in Horses

Prevention focuses on fly control, wound care, sanitation, and biosecurity. Use the fly-control plan your vet recommends for your region and season. That may include repellents, fly sheets, masks, manure management, and feed-through insect growth regulators started early in fly season. Pay extra attention to the ventral midline and any area with skin irritation, since flies often target those sites.

Check your horse daily for cuts, scrapes, rain rot, girth rubs, or other skin damage. Clean wounds promptly and protect them from flies and contamination. Do not share grooming tools, tack, towels, or buckets between infected and healthy horses. If a horse develops a draining abscess, isolate that horse, wear gloves, wash hands well, and collect and dispose of drainage and contaminated supplies so pus does not spread into stalls, aisles, or paddocks.

Environmental control matters because the organism can survive for up to two months in hay and shavings and more than eight months in soil, with manure helping it persist. New arrivals should be monitored carefully and ideally separated for 7 to 14 days before joining the resident group, with longer separation if they come from a facility with recent infection.

There is now a conditionally licensed commercial vaccine in the United States for control of C. pseudotuberculosis in horses, mainly considered for horses living in endemic areas. It is not a stand-alone solution, and your vet can help you decide whether it fits your horse's risk profile alongside a broader prevention plan.

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