Veterinarians have recently diagnosed more than 10 horses residing in southern Alberta, Canada, with pigeon fever (Corynebacterium pseudotuberculosis infection), according to a health alert from Equine Canada. 

Traditionally diagnosed in horses residing in the western United States, pigeon fever—also known as dryland distemper—incidence has increased considerably in other regions, including the Midwest, over the past decade.

Researchers believe the soil-dwelling C. pseudotuberculosis gains access to horses’ bodies through abrasions or wounds on the skin or mucous membranes, and studies have shown that many insects—including the horn fly, the house fly, and the stable fly—can transmit the disease.

Pigeon fever often produces mild fever and pectoral abscesses that give an appearance similar to a pigeon’s protruding breast. Less commonly, the condition can produce deep abscesses in a horse’s lungs, kidneys, or liver, or the disease can manifest as an infection of the limbs, termed ulcerative lymphangitis.

Treatment for external abscesses is relatively easy and involves a veterinarian lancing and draining the abscess. Owners must also practice good hygiene to avoid further infection. In severe cases veterinarians might employ antimicrobial medications to treat internal abscesses and ulcerative lymphangitis. Many affected horses recover.

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