Pigeon Fever Cases Identified in Northwest Arkansas
Dr. Jeremy Powell, Associate Professor and Veterinarian, University of Arkansas
A handful of pigeon fever cases have recently occurred in northwest Arkansas near Springdale. Pigeon fever is a disease that causes abscesses and a mild fever in horses. The disease is typically more prevalent in drier climates and is not common for Arkansas, but this year’s drought conditions may have been ideal for disease development.
Pigeon fever is due to an infection by the bacterium Corynebacterium pseudotuberculosis that leads to pectoral abscesses in the chest area. The abscesses cause the appearance of a protruding breast muscle, which gives the appearance of a pigeon breast and hence the name, “pigeon fever” (see Figure 1). Abscesses may also occur along the belly and the lower neck region or on a front or rear limb of an infected horse. Affected horses may appear weak and exhibit stiffness or lameness associated with the swollen tissue. At first glance, an owner of an infected horse may think their horse has been injured due to a kick from another horse.
The infectious organism usually lives in the dry soil and manure. Transmission of this disease is usually due to flies, but horse- o-horse contact or contact with contaminated soil or tack can also allow the infectious bacteria to affect a susceptible horse. Although people are not infected by this disease, they can inadvertently transmit the organism on clothing, hands and shoes. Recent cold snaps should help decrease the chance of this disease spreading; however, during the early fall, balmy temperatures and dry conditions were prime for disease development.
Pigeon fever is a treatable disease, and most cases lead to superficial abscesses that are treated with heat packs and lancing for drainage. Once the abscess is surgically lanced, it should be cleaned and flushed daily with disinfectant. Most cases do not require antibiotics, and many veterinarians feel that antibiotics may delay abscess maturation. Furthermore, deep abscesses may occur in the lungs or other internal organs. These occurrence are much less common but may require antibiotic therapy.
If horse owners suspect their horse may be infected, a veterinarian should be contacted for treatment assistance. The infected horse should be isolated to minimize the likelihood of exposing other horses. Also, keep in mind that discharge from a ruptured abscess contains a high number of bacteria and can contaminate the environment. Any tack or other equipment such as brushes, buckets or bedding should be disinfected with a mild bleach solution. Owners need to maintain good hygiene after handling a sick horse. Good fly control will also help limit the spread of this disease to other horses.
Currently, there is no commercially available vaccine for the disease. Horses that have experienced an infection will have immunity for several years against the infectious bacteria. Other farm animals such as sheep and goats can become infected with a different strain of the same organism. Cattle can become infected with either strain, and infected cattle could act as vectors of this disease to horses (or vice versa).