Pigeon Fever

Caused by the hardy bacteria Corynebacterium pseudotuberculosis, pigeon fever can be highly contagious if not properly managed. The disease is seasonal, with peak incidence in the dry or fall months, and the incidence fluctuates from year to year within a site. The distribution of this disease appears to be expanding, and outbreaks in areas in which the bacteria had previously not been reported have occurred during times of drought. In addition to horses, sheep, goats, cattle, buffalo, and camelids can also be infected by this bacteria.

Oregon Cases: 2026

According to the ODA, in August 2026, one horse in Deschutes County, has tested positive for pigeon fever, and five horses are suspected to be positive. Another 44 horses have been exposed. The affected horses are under quarantine. 

Symptoms

It is most often characterized by intramuscular abscesses, primarily in the pectoral area and ventral part of the abdomen, which gives the horse a puffed-out appearance similar to that of a pigeon. The infection is confirmed with a bacterial culture and by symptoms. Other symptoms are lethargy, stiffness and lameness from the pain and swelling. Some horses have internal abscesses and may not have concurrent external abscesses. Horses with internal infection are more frequently seen one to two months following the peak number of cases with external abscesses.

Horse should be checked daily; look closely at the underside and check for swelling. In some cases, the infection can spread to the horse’s legs, causing a syndrome called ulcerative lymphangitis, which is more challenging to treat.

How It Is Spread

The bacteria lives and multiplies in dry soil and manure. Hot, dry weather facilitates this bacterial growth. Horses contract the disease through an open wound or fly bite, with bacteria entering through these abrasions or wounds and, sometimes, mucous membranes.

Several years ago, an Oregon veterinarian who was treating horses with pigeon fever contracted the bacteria. This case highlights the importance of wearing gloves while caring for infected horses and following disinfection protocols.

Prevention & Treatment

• Humans can also carry the bacteria on their boots, hands, and tools. Proper disinfection protocols should be utilized to limit the spread of the bacteria. Gloves should be worn when handling infected horses. Wash hands diligently when flushing abscesses and handling infected horses.
• Collect and dispose of all purulent material and contaminated supplies when treating infected horses. Do not allow purulent material to drain onto the floor or other environmental surfaces.
• Bedding, water buckets, and any other material that might come in contact with pus should be disinfected or disposed of and not shared with other horses.
• Separate infected horses from naive and/or unvaccinated herd mates
• The organism has been shown to survive for up to two months in hay and shavings, and more than eight months in soil samples at environmental temperatures. The most aggressive prevention method to help limit the spread of the bacteria is to remove the top layer of soil in the area that is contaminated by wound drainage and replace it with clean soil or bedding. Bleach and other disinfectants do not work well on organic debris (dirt or manure), so pouring disinfectants on the ground is not effective. Bleach does work well on clean surfaces, like stall mats and scrubbed walls.
• Fly control (sprays, sheets and repellents) can help to limit disease risk, as can meticulous manure clean-up. Reduce insect exposure by regular application of insect repellant, particularly to the ventral midline.
• Practice meticulous wound care (topical fly repellants, antimicrobial ointments, and bandages) to prevent contamination.
• Treatment may involve lancing and draining the abscesses and, in some cases, antimicrobials. An ultrasound can help to locate deep internal abscesses and find the best place to drain them. A horse is unlikely to be contagious if all abscesses have healed.
• A conditionally-licensed commercially available vaccine is available in the United States for control of pigeon fever in horses, and is recommended in conjunction with multifaceted insect control for horses residing in endemic regions.

For more information on pigeon fever, please consult with your veterinarian.