Picture Belgian draft horse
Picture Shire horse
Picture Clydesdale
 CHRONIC PROGRESSIVE SWELLING, HYPERKERATOSIS AND
FIBROSIS OF DISTAL LIMBS IN CLYDESDALES, SHIRES AND
BELGIANS SUGGESTIVE OF CHRONIC LYMPHEDEMA.
 RESEARCH PROJECT
 HOW TO SUPPORT THE PROJECT
 CONTACT INFORMATION
 PUBLICATIONS
 PROJECT SECURED AREA
 CHRONIC PROGRESSIVE SWELLING, HYPERKERATOSIS AND
FIBROSIS OF DISTAL LIMBS IN CLYDESDALES, SHIRES AND
BELGIANS SUGGESTIVE OF CHRONIC LYMPHEDEMA.
A condition characterized by progressive swelling, hyperkeratosis and fibrosis of distal
limbs has been recognized in Shires, Clydesdales and Belgian Draft horses. This chronic
progressive disease starts at an early age, progresses throughout the life of the horse and
often ends in disfigurement and disability of the limbs which inevitably leads to the
horse’s premature death. The pathologic changes and clinical signs closely resemble a
condition known in humans as chronic lymphedema or elephantiasis nostras verrucosa.
The lower leg swelling is caused by abnormal functioning of the lymphatic system in the
skin, which results in chronic lymphedema (swelling), fibrosis, a compromised immune
system and subsequent secondary infections of the skin. Based on preliminary research, it
appears that a similar pathogenic mechanism is involved in the disease that affects these
specific draft horse breeds. The clinical signs of this disease are highly variable. The
earliest lesions are characterized by skin thickening and crusting; both are often visible
only after clipping the long feathering. Secondary infections develop very easily in these
horse's legs and usually consist of either chorioptic mange or bacterial infections. Both
dark and white skin on the lower legs are equally affected. These lesions are consistent
with pastern dermatitis, a process also seen in other breeds. In Shires, Clydesdales and
Belgians however, these lesions do not respond well to therapy. As the condition
becomes more chronic, the lower leg enlargement becomes permanent and the swelling is
firm on palpation. More thick skin folds and large, poorly defined, firm nodules develop.
The nodules may become quite large and often are described as "golf ball" or even
"baseball" in size. Both skin folds and nodules first develop in the back of the pastern
area. With progression, they may extend and encircle the entire lower leg. The nodules
become a mechanical problem because they interfere with free movement and frequently
are injured during exercise. This disease often progresses to include massive secondary
infections that produce copious amounts of foul-smelling exudates, generalized illness,
debilitation and even death.
Picture early lesion
Picture chronic lesion
Picture distribution lesion
 RESEARCH
For the last two years, a Center for Equine Health scientific team, led by Dr. Hilde De
Cock and Dr. Verena Affolter, has been studying this disease. They have employed
several different investigative techniques in an attempt to find the underlying cause of
this serious and debilitating disease. These researchers utilized histopathologic and
radiographic imaging techniques to examine the skin, blood and lymph flow of the distal
limbs of normal and affected draft horses. Detailed examinations of tissues from
pathological specimens and skin biopsies are conducted using several different
methodologies in an attempt to define and delineate the basic pathogenic features of the
condition. This research team now understands that this condition is primarily a
lymphatic disease, and that the pastern dermatitis, draft horse owners have been
struggling with for years, is a secondary result due to the body's inability to properly
remove fluids and oxygenate the skin of the lower leg. We know that the lymph system
breaks down over time and that protein-rich fluid leaks into the tissues of the lower leg,
which results in fibrosis of the tissues under the skin and thickening of the skin itself.
The clinical signs and pathologic changes resemble closely a condition known in humans
as chronic lymphedema or elephantiasis nostras verrucosa. In order to develop a
successful treatment or management strategy for these horses the research team recently
started a thorough research project in cooperation with Professor Barry Starcher from the
University of Texas Health Center at Tyler, Texas, USA and Professor Richard Ducatelle
from The University of Gent, Merelbeke, Belgium. The project is generously sponsored
by THE LEONARD X. BOSACK & BETTE M. KRUGER FOUNDATION,
AYRSHIRE FARM, THE BELGIAN NATIONAL STUD BOOK and SEVERAL
UNITED STATES DRAFT HORSE BREED ASSOCIATIONS, INDIVIDUAL
DRAFT HORSE OWNERS and the UC DAVIS, CENTER FOR EQUINE
HEALTH.
In the next couple of years this group of researchers will focus on developing better
diagnostic tools to detect the disease in the early stages in association with the
development and evaluation of possible therapeutic treatments and strategies.
Concurrently significant effort will be put in complete characterization of the disease and
better understanding of the pathogenic mechanism underlying this disease.
HOW TO SUPPORT OUR RESEARCH
Are you a concerned draft horse owner, or maybe just a person who admires the majesty
of these "gentle giants?" Would you like to help in the international effort to find a cure
for the devastating disease of "Chronic Progressive Lymphedema?" You can help in one
or more of three ways.
First, of course, is by making a financial donation to support the research. Donations of
any amount will help. Checks should be made out to the Regents of the University of
California and accompanied by a letter stating that your gift is for the draft horse research
studies at the Center for Equine Health. Send donations to:
Center for Equine Health
School of Veterinary Medicine
University of California
One Shields Ave.
Davis, CA
95616-8589.
Second, if you own draft horses and would be interested in cooperating in our study by
letting us take a skin biopsy and blood sample from your horse(s), please contact Dr.
Gregory L. Ferraro via e-mail at glferraro@ucdavis.edu or by phone at (530) 752-6433.
We may not be able to take advantage of everyone's offer, but the more horses we have
available for study, the easier it will be for us to collect our needed samples.
Third, if you have an affected horse that you would like to donate to the Center for
Equine Health, please contact Dr. Ferraro. Donations of horses will depend on proximity
to Davis, your horse's health status and the donor's ability to assist with transport
expense. We don't need many animals, but some will be necessary to complete the
research.
We thank you all in advance for your willingness to contribute to this worthy endeavor!
 CONTACT INFORMATION
Additional information can be obtained from the following persons:
Dr. Hilde De Cock: hedecock@ucdavis.edu
Dr. V. Affolter: vkaffolter@ucdavis.edu
Dr. G. Ferraro: glferraro@ucdavis.edu
LINKS
Link to Department of Pathology - Bacteriology - Poultry diseases, University of Gent,
Belgium,
Link to horse report Volume 21, Number 2, April 2003
Link to horse report Volume 19, Number 4, Oct 2001
 PUBLICATIONS
1. Van den Eynde H. The Belgian Draft Horse has Painful Limbs (Belgisch trekpaard heft
zere benen). Science section of a Belgian newspaper "De Standaard" 2002; November 29.
2. Verstraete J. The Belgian draft horse in danger (Belgisch trekpaard bedreigd). Gent
Universiteit 2003;17(4):26-29.
3. De Brauwer P. Health status of the limbs of Belgian draft horses (Gezondheid van de
benen van trekpaarden). Landbouwleven February, 14th, 2003.
4. Equus
5. The Horse Report. Volume 21, Number 2, April 2003.
6. The Horse Report.Volume 19, Number 4, Oct 2001.
Scientific papers:
De Cock et al. Progressive swelling, hyperkeratosis and fibrosis of
distal limbs in Clydesdales, Shires and Belgian draft horses suggestive of
primary lymphedema" accepted in Lymphatic Research and Biology, Vol. 1
# 3.
 PROJECT SECURED AREA
Will only be accessible by Hilde De Cock, Verena Affolter, Greg Ferraro, Jim
MacLachlan, Leen Vanbrantegem and Barry Starcher
Will contain space for input new data and space for downloading most recent data.
Information needed on this page for new input:
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Horse pathology number
Breed
Name
Results skin neck (A)
Results skin forelimb (B)
Results urine
Information needed on this page for most recent data (Excell sheet):