Equine owners should be extra vigilant for signs of pigeon fever in their horses, according to Colorado State University veterinarians. A spike in reported cases of this infectious disease has been reported in the northern Front Range of Colorado.

This highly contagious disease is also called pigeon breast, breastbone fever, false strangles, dryland strangles, or dryland distemper. Signs of pigeon fever can initially resemble those of other diseases such as strangles. Sometimes the only initial signs are lameness and a reluctance to move. Other signs include lameness, fever, lethargy, and weight loss. There might also be very deep abscesses and multiple sores along the horses’ chest, midline, and groin area. Abscesses in other areas such as the back, flank, or ears have been seen but internal abscesses are rare. Horses can be infected for several weeks before developing signs of the disease, especially abscesses.

The disease, which can be fatal, is caused by bacteria called Corynebacterium pseudotuberculosis. The bacteria live in the soil and can enter the animal’s body through wounds, broken skin, or mucous membranes. Research also indicates that the disease might be spread via flies, especially cattle horn flies. These are biting flies that tend to feed under the belly of the horse. The flies transmit the bacteria from horse to horse when they have been in contact with pus draining from abscesses. Bacteria in drained puss can survive up to 55 days in the environment.

Pigeon fever can affect a horse of any age, sex, or breed, but it usually attacks young adult animals. Humans cannot catch pigeon fever, but they can spread it from horse to horse because the bacteria can be carried on shoes, clothing, hands, or barn tools. Any horse showing signs of pigeon fever should be isolated to prevent spread to other animals. Areas where infected horses are held must be properly cleaned and completely disinfected