This document discusses chronic progressive lymphedema (CPL) in draft horses. CPL is likely caused by a congenital malformation of the lymphatic system that causes a buildup of fluid in the tissues over time. Clinical signs of CPL include swelling in the distal limbs that progresses to hard, nodular skin with folds and ulcerations prone to secondary infections. Diagnosis is based on clinical signs, and treatment focuses on good skin care, exercise, bandages, and manual lymph drainage to push fluid out of the tissues and prevent further damage. Histology of affected skin shows extremely dilated and degenerated lymphatics.

1. CHRONIC PROGRESSIVE LYMPHEDEMA IN DRAFT HORSES Prof. Dr. H. De Cock University of Antwerp

3. 1.The lymphatic system of the skin

6. 2. What is lymphedema? Lymph vessels are abnormal in structure (congenital malformation or secondary to trauma) -> accumulation of fluids in tissue -> tissue swelling -> hypoxia of tissue -> skin fibrosis (hardening), hyperkeratosis and secondary bacterial infections (not proper functioning of immune system)

8. 4. CPL in draft horses Clinical signs: Starts with mild enlargement distal limbs -> skin folds in pastern region -> hyperkeratosis and ulceration skin -> swelling becomes hard and nodular -> secondary skin infections -> lymphangitis

9. CPL mild lesions Scratches or pastern dermatitis looks similar in initial stages

10. Lymphedema ≠ Scratches Cause is poor function of lymph vessels Many possible causes Slowly progressive Usually does not progress No or minimal improvement with regular treatment Cure with good treatment All 4 limbs affected 1 or 4 limbs affected

20. Lymphangiography

21. Histology Extremely dilated and degenerated lymphatics, proliferation of blood vessels (hypoxia), edema, inflammation and degenerated elastin surrounding the lymphatics in CPL

22. Normal lymphatic In CPL

23. Normal lymphatic In CPL

24. Elastin difference between normal (left) and CPL (right)

28. treatment 2. Supportive elastic bandages, life long and as much as possible Reason: pushes accumulated fluid out of the skin

29. treatment 3. Lots of exercise Reason: muscle movement pushes fluid out of the tissues

31. Results of treatment: lesions before and after treatment

32. Met dank aan iedereen die meewerkte aan het project: Eigenaars Dierenartsen Leen Van Brantegem (UA) Verena Affolter & Greg Ferraro (UCDavis) Prof. Ducatelle (UGent) Technisch personeel UA, UGent & UCDavis