October/November 2017 Horse Around New Mexico – What to do if Pigeon Fever Strikes.
What to do if Pigeon Fever Strikes
by Stacie G. Boswell, DVM — originally published in Horse Around New Mexico, October/November 2017
This article is provided for general information only. It is not a substitute for veterinary examination, diagnosis or treatment. Please consult a licensed veterinarian before beginning any treatment or making decisions about your horse’s care.
The text below was read from the printed magazine using optical character recognition and lightly edited for the web, so that this article can be found and read online. The original article as it appeared in print is reproduced at the foot of this page and is the version of record — where the two differ, the printed version is correct. If you spot an error, please let us know.
Pigeon Fever is increasing throughout Texas and the Rocky Mountain regions, which includes New Mexico. All horses are at risk.
PIGEON FEVER STRIKES
ecause Pigeon Fever is spread by flies and contact, any horse that is not confined better yet, reduce the chances of getting and spreading Pigeon Fever…
It's Pigeon Fever season! Also known as Dryland Distemper, False Strangles, and sometimes locally as Pigeon Breast, this highly-contagious disease has a peak incidence during the hot, dry end of summer and the fall months.
Pigeon Fever is always a concern in New Mexico. Researchers recently confirmed that there has been an increasing incidence of cases in the past ten years, particularly in Texas and throughout the Rocky Mountain regions.
Spread by flies or contact
Pigeon Fever is caused by Corynebacterium pseudotuberculosis. The bacteria invade the skin through a disruption such as a fly bite, a small cut, or abrasion. The original skin wound is so small that it goes unnoticed. Another way a horse can pick up the bacteria is by direct contact with pus from an infected horse, off shared tack, grooming materials, or even a handler's clothing or hands.
Pigeon Fever is said to be highly contagious; however, some horses seem to develop immunity to it.
The incubation period is three to four weeks. The bacteria can survive in the soil for up to eight months. Because of this prolonged survival and long incubation period, how an individual horse was exposed often remains a medical mystery.
Signs of infection
At the site of bacterial entry, swelling will eventually occur. The abscess is often on the front of the pectoral muscles, at the base of the neck, or on the belly. Abscesses can also occur on the head or near the sheath or udder. If the abscess is near or on a leg, lameness may occur.
Over time, the infected tissue swells, and the abscess may rupture spontaneously. More than one abscess is often present. There may be generalized swelling of the tissue surrounding the abscess. As the abscess progresses, the horse will experience much pain until the abscess ruptures or is drained.
Uncommonly, bacteria enter the horse's body and cause internal abscesses. These are difficult to identify and treat, and occur in about 2-8% of known cases. Horses with internal abscessation
may have no known external abscesses. These horses may have chronic colic, weight loss, or lameness. Finally, the bacteria may enter the body and infect the lymph portion of the circulatory system. Horses with this problem experience extreme limb swelling and draining tracts.
Calling your veterinarian to treat Pigeon Fever is always warranted. The abscess should be identified by the vet. Then it is clipped, cleaned, and a local anesthetic is instilled. The abscess will be lanced, drained, and then flushed with an antiseptic.
Bacterial testing is important for confirming which bacteria are present and choosing an effective antibiotic. Antibiotics are not always necessary for external abscesses. However horses with limb swelling or internal abscesses should be treated with appropriate antibiotics for an extended period of time – at a minimum, one month.
Because of the pain and swelling, a non-steroidal anti-inflammatory drug will be administered to help the horse feel better. Finally, one of the most important parts of treatment: daily cleansing and flushing of the abscess site. The tissue must heal from the inside out. It will seem slow at first, but will rapidly progress after about two weeks as the infection is cleared.
Follow your veterinarian's instructions on how to flush and clean the wound. Isolate the buckets and other materials you use to clean the wound so other horses are not in contact with them.
Use bleach to disinfect anything you use for the job. Cleaning the wound can be messy, so beware of picking up any pus on your clothes, hands, arms, or even shoes. Wear gloves and wash your hands thoroughly after working with an infected horse.
Change your clothing before you work with other horses. PHOTOS FROM LEFT: A horse with Pigeon Fever showing the typical swelling at an abscess site at the base of the neck; A horse with chronic limb swelling (of several years' duration) after damage to the lymphatic system; A horse with Pigeon Fever showing pus being drained from a mature abscess. The volume of pus can be surprisingly large! (PHOTOS BY STACIE G. BOSWELL.)
Fly control is critical to controlling the bacterial spread, but even meticulously kept horses can fall victim to this disease. It also helps to keep pens clean, and to minimize objects that can cut or puncture skin, such as barbed wire.
If a horse on your property comes down with Pigeon Fever, it's very important to take biosecurity seriously. Measures that help include: Sanitize pen or stall with bleach or other disinfectant to the best extent possible.
Wear gloves while working with the horse, and immediately wash hands afterwards. Discard or bleach contaminated grooming supplies or brushes that were used on the infected horse. – Keep healthy horses away from affected horses.
Keep the flies off the draining abscess and away from infected tissue. Once the draining pus ceases, and the tissue is healing, biosecurity can be relaxed.
With good reason, horse owners can worry that their horses may contact Pigeon Fever. If your horse is diagnosed with Pigeon Fever, be responsible and let potential visitors and nearby horse owners know you have an infected horse. Keep your horse isolated on your property until he or she thoroughly heals. Follow the protocols, control flies, and take heart: while unsightly, messy, and painful for your horse, nearly all horses heal well and have no long-lasting effects.
Stacie G. Boswell, DVM, DAC/S is a board-certified large animal educational outlets to improve the lives of horses. She can be reached at stacieboswell@gmail.com. She is now based in Ruidoso, NM at Franklin Veterinary Clinic.
The article as it appeared in print:
Here is the link to the entire magazine on Issuu: https://issuu.com/ceciliakayano/docs/horse_around_octnov_2017_e90c9b8ddd314d.