Epizootic Lymphangitis: A Working Equid Disease

Epizootic Lymphangitis: A Working Equid Disease

Working horses undergo treatment for the fungal disease epizootic lymphangitis (EZL) at the Society for the Protection of Animals Abroad veterinary clinic in Debre Zeit, Ethiopia. Both animals' limbs are affected, but the horse on the left also suffers from facial lesions.

Photo: Stephanie L. Church, Editor-in-Chief

Equine researchers in the U.K. hope to define better the transmission methods of a fungal disease, called epizootic lymphangitis (EZL), that causes painful skin and eye lesions and leads to lameness and loss of use in working horses and donkeys throughout the developing world.

Gina Pinchbeck, BVSc, Cert. ES, PhD, Dipl. ECVPH, MRCVS, senior lecturer in veterinary epidemiology at the University of Liverpool, in the U.K., and her colleagues are currently studying EZL. She presented what they have learned about the disease at the first Havemeyer International Workshop on Infectious Diseases of Working Donkeys, held Nov. 19-21, 2013, in Addis Ababa, Ethiopia.

There are three forms of the disease, which is caused by a fungus called Histoplasma capsulatum var. farciminosum—cutaneous (skin), ocular, and respiratory. She explained that a cutaneous EZL case starts as a single nodule that erupts. The infection travels though the lymphatics, causing swelling of the limbs and nodules elsewhere on the body.

“The horse can become debilitated and develop secondary infections … sometimes with joint involvement,” she says. “Quite often they’re abandoned at this point and seen by the road. The theory is that they want to stand where there are less flies,” likely because of air currents from the passing traffic.

Veterinarians see the ocular form less frequently. Cases start as a persistent conjunctivitis and swelling, and sometimes the infection spreads into the facial tissues, seen as small nodules. If cases go untreated, secondary infections and severe ocular disease can occur.

Epizootic lymphangitis (EZL) lesions on the legs of a working horse under treatment at the Society for the Protection of Animals Abroad veterinary clinic in Debre Zeit, Ethiopia. This horse was euthanized later this day because of the extent of the damage and discomfort caused by the lesions.

Photo: Stephanie L. Church/TheHorse.com

Cutaneous lesions are also seen in the respiratory form of the disease but are accompanied by nasal discharge and severe coughing. On post-mortem horses have damage throughout their respiratory systems.

Veterinarians have reported cases of EZL in Ethiopia, Sudan, The Gambia, Senegal, Egypt, Nigeria, Iraq, India, and China, among other countries. Occurrence could be dependent on altitude or rainfall, said Pinchbeck.

The disease ranks high among working equid owners as a major problem; when Pinchbeck and her graduate students conducted participatory studies to prioritize diseases of African working equids, 11 out of 17 groups and 14 out of 16 groups ranked EZL as the most important disease.

“There’s a big desire to find a solution for the disease,” she says. “It’s a serious welfare issue because it’s difficult to treat and causes abandonment.” That makes the problem a socioeconomic one, as well. “Many owners acknowledge the disease has a direct economic impact due to its chronic and debilitating effect. They will continue to work the horse as long as possible but ultimately they become so affected they can no longer work.”

The fungus is sensitive to treatment with antifungals, but these medications simply are not affordable. Currently, control is quite difficult, says Pinchbeck: Veterinarians lance all of the nodules and infuse them with a 4% tincture of iodine. Resolution using this method can take up to two months and is only successful if treated early.

Until they determine the exact route of transmission and effective preventive techniques—which will only come about with more funded research—all veterinarians can do is advise owners to seek treatment early and prevent wounds, Pinchbeck says.

Look for the upcoming March cover story in The Horse: Your Guide To Equine Health Care on targeting infectious diseases in working donkeys and horses.

About the Author

Stephanie L. Church, Editor-in-Chief

Stephanie L. Church, Editor-in-Chief, received a B.A. in Journalism and Equestrian Studies from Averett College in Danville, Virginia. A Pony Club and 4-H graduate, her background is in eventing, and she is schooling her recently retired Thoroughbred racehorse, Happy, toward a career in that discipline. She also enjoys traveling, photography, cycling, and cooking in her free time.

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