Pigeon fever

Pigeon Fever (also: Dry Land Distemper in Horses or Equine Distemper) is a disease that causes abscesses in horses, sheep and cattle.

Pigeon Fever is sometimes confused for Strangles, another infection that causes abscesses. Pigeon Fever is caused by the gram positive bacteria Corynebacterium pseudo tuberculosis. This bacterium is present in soil and is transmitted to horses through open wounds, abrasions or mucous membranes.^[1] Infected horses commonly have swelling in the chest area, making it look similar to a 'pigeon chest'. This disease is common in dry areas like California, Arizona, New Mexico and other areas.^[2]

Symptoms

There are three common forms of pigeon fever that affect horses; ulcerative lymphangitis, external abscess, and internal infection. Infected horses may show mild to extreme symptoms. Severity of symptoms can be different for each horse depending on various factors such as age, immune system, health and nutrition. Symptoms may not occur immediately as the bacteria has an incubation period of 3-4 weeks.^[3]

Ulcerative lymphangitis

This is the least common form of pigeon fever seen in horses. It is characterized by severe limb swelling and cellulitis in one or both hind limbs and can lead to lameness, fever, lethargy and loss of appetite. It is imperative that antimicrobial and anti-inflammatory treatments are used to prevent further complications such as limb edema, prolonged or recurrent infection, lameness, weakness and weight loss.^[1]

External abscess

External abscesses are the most common form of pigeon fever seen in horses. Abscesses develop on the body, usually in the pectoral region and along the ventral midline of the abdomen. However, abscesses can also develop on other areas of the body such as the prepuce, mammary gland, triceps, limbs and head. The fatality rate for this form infection is very low. The abscess is often drained once it has matured.^[1]

Internal infection

Only 8% of infected horses have this form of pigeon fever, however, it has a 30-40% fatality rate. Organs that are commonly affected are the liver, spleen, and lungs. For a successful recovery, long-term antimicrobial therapy is essential.^[3]

Treatment

Treatment can vary depending on many factors, such as age of horse, severity of symptoms and length of infection. As long a horse is eating and drinking, the infection must run its course, much like a common cold virus. Overtime a horse will build up enough antibodies to overtake and fight the disease. Other treatment options can be applying heat packs to abscesses to help draw it to the surface and using drawing salves such as Ichthammol. A blood test or bacterial cultures can be taken to confirm the horse is fighting Pigeon Fever.^[1] Anti-inflammatory such as Bute can be used to ease pain and help control swelling. Treating Pigeon Fever with antibiotics is not normally recommended for external abscesses since it is a strong bacterium that takes extended treatment to kill off and to ensure it does not return stronger. However, if the abscesses are internal then antibiotics may be needed.^[4] Consulting a Veterinarian for treatment is recommended. Making the horse comfortable, ensuring the horse has good food supply, some extra vitamins and quality hay will help the horse keep their immune system strong to fight off the infection. Once the abscess breaks or pops, it will drain for a week or two. During this time keeping the area clean, applying hot packs or drawing salves will help remove the pus that has gathered in the abscess.

Prevention

It is important to reduce the amount of environmental contamination to prevent the spread of insects or fomites. Owner's should regularly apply insect repellent and routinely check their horses for open wounds to prevent chance of infection.^[1] A regular manure management program is recommended, including removal of soiled feed and bedding, as the bacteria can survive in hay and shavings for up to two months.^[1] Since the disease lives in the ground and is spread by flies, pest control is a good defense but not a guarantee. Horses being introduced to new environments should be quaruntined and any infected horses should be isolated to prevent spread of the bacteria.^[3] There is currently no vaccination for Pigeon Fever.^[3]

Notes

References