22 Interesting Facts About the Equine Lymphatic System

Superficial Lymph System
Lymph Capillaries in the Tissue Spaces
Deep Lymph System

Here are 22 interesting facts about the equine lymphatic system:

  1. The equine lymphatic system is a network of vessels and organs that play a crucial role in the body’s immune system.
  2. It includes lymph fluid, lymph nodes, lymphatic vessels that make and move lymph from tissues to the bloodstream, the spleen, thymus and bone marrow.
  3. Lymph is a clear-to-white fluid similar in composition to blood plasma. It holds proteins, fats and white blood cells (lymphocytes that can rapidly multiply and release antibodies in response to bacteria, viruses, dead or dying cells, abnormally behaving cells such as cancer cells and a range of other stimuli).
  4. The lymphatic system transports lymphatic fluid around the body in delicate one-way vessels, organized in a series of pathways alongside blood vessels throughout the body.
  5. Lymph is moved through the lymphatic vessels by the contraction of smooth muscles in the vessel walls and by movement of the muscles and body.
  6. The lymphatic system helps to remove waste, excess fluid and bacteria from the body’s tissues and transports immune cells to areas of the body where they are needed to fight infections.
  7. The lymphatic system also maintains the volume of the blood, the health of the interstitium and connective tissue, fluid balance within the body and is responsible for protein circulation.
  8. A mature horse has approximately 10-15 liters of lymph fluid in its body. This amount can increase in response to injury or infection.
  9. An average horse has around 8000 lymph nodes, while an average human has around 600.
  10. It’s estimated that lymph circulates through the average horse’s body at a rate of about 60 to 90 milliliters per hour. The rate of lymph circulation can vary depending on a number of factors, including the size of the horse, the health of the lymphatic system, and their level physical activity.
  11. Equines are more prone than other mammals to experience lymphatic ‘bottlenecks” as lymph slows down and becomes concentrated as it enters a node.
  12. Damaged lymph nodes can regenerate if there is still a blood and nerve supply. They can also try to join another functioning lymph vessel or vein.
  13. Horses have a unique lymphatic structure called the pre-iliac lymph node, located near the hind limbs that plays a key role in the drainage of the horse’s lower limbs.
  14. Tendons in the leg have a high density of lymphatic vessels compared to blood vessels.
  15. These vessels can be damaged by restrictive stable bandages.
  16. The equine lymphatic system can be affected by a variety of conditions, including infections, cancer, and injuries, which can lead to swelling, pain, and other symptoms.
  17. Lymphangitis is a degenerative condition that affects the lymphatic vessels and causes swelling, pain, and fever. New treatments show great promise (see below).
  18. The lymphatic system is designed to function at its best in horses that are moving throughout the day, covering large distances as they forage. When a horse stands still, the transport ability of the lymphatic system decreases significantly. This puts a standing horse at a distinct disadvantage when recovering from injury or exertion. 
  19. The lymph collectors in the outer layers of a horse’s skin are made of about 40% elastic fibers, much more than a human’s. This helps it act as a “compressive bandage”, stiffening and exerting force when mobile. This high proportion of elastic fibers may have developed because there are no muscles in the lower limbs to aid the contraction of the vessels.
  20. Any restriction in fascia, muscle, and mobility can restrict lymphatic flow and lead to reduced functionality of this system, leading to pooling of lymphatic fluid in the horses body.
  21. A Lymph Drainage Massage uses light rhythmic movements to stimulate the lymphatic system, without pressing hard on the vessel. These light strokes help the lymph fluid move gently through the nodes and tissues.
  22. Horses tend to respond very effectively to manual lymphatic drainage.

Lymph needs to be flowing for the horse to be healthy. Lymphatic drainage massage helps stimulate the movement of stagnant lymph and enhance the performance and natural flow of the lymphatic system. Lymphatic drainage massage can help by reducing stocking up, improving recovery after strenuous exertion and aids in recovery from certain injuries or ailments including laminitis, surgery, Lymphedema and tendon injuries.

* Please Note – There are a number of very serious contraindications for lymphatic massage including active infections, allergic reactions and cancer, due to the possibility of spreading the infection throughout the body. Use only under close veterinary supervision.

** To learn more about early signs of Lymphangitis and promising new treatments for old and new cases:

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