Principal Body System: Lymphatic
Definition: Lymph, lymphatic vessels and structures or organs containing lymphatic tissue (large numbers of white cells called lymphocytes) such as the spleen, thymus gland and lymph nodes
Function: Returns proteins and plasma to the cardiovascular system; transports fats from the GI tract to the cardiovascular system; filters body fluids; produces white blood cells, and protects against disease
The lymphatic system is a major part of the immune defence system, but the lymphatics are probably right at the bottom of the list when it comes to being noticed - it's certainly one of the least remembered systems.
Yet the lymphatic system is absolutely critical for health. Think of it as the body's waste disposal system - it's essential for eliminating waste. It plays an essential role in the body's natural - and very sophisticated - detoxification system, and without it working properly, the body will get very, very sick. Without a properly functioning (although largely invisible) lymphatic system, the body would quite simply drown in its own waste.
Science Alert 🤓 - The lymphatic system has three main functions: fluid recovery, immunity, and lipid absorption, lipids being essential fat molecules which make up the building blocks of the structure and function of living cells. It also rids the blood of acidic and toxic waste, filtering the toxic matter into the body’s two main detox filtration organs, the liver and kidneys.
The whole lymphatic system resembles a second circulatory system alongside the blood circulatory system. It's connected together by a web of tiny (lymph collector) vessels under the skin transporting its own fluid (lymph) which carries proteins and lymphocytes (the body's killer-army of white blood-cell pathogen destroyers) to various tissues in the body for cleansing and sorting, to maintain a healthy, cleansing fluid-balance within the body. The lymph travels into larger, deeper vessels which eventually discharge into the blood stream.
Here's an eye-opener - would you believe that a whopping 70% of the horse’s body is water, so this means that anything affecting this vital fluid balance can have a profound effect on the horse’s well being. If movement is limited or in the event of severe illness, toxins can build up and blockages (i.e. puffy legs) appear. If the skin breaks, infection can occur, and it's all the more difficult to treat as by now the immunity system overall will be significantly compromised.
Lymph is literally the body's liquid rubbish bin - it picks up waste products formed from all the chemical reactions needed to keep the body alive, ushering them onwards to the exit door, as well as all the toxic load of environmental chemicals that need to be removed from the body before they start wreaking biological havoc.
Lymph is a clear watery fluid, around 95% water with the fancy name of interstitial fluid. It's filled with those killer-army lymphocytes mentioned above, alongside a small concentration of red blood cells and proteins, and it circulates through the body tissues via its system network, collecting harmful materials along the way for disposal, typically bad fats/bacteria and so on, filtering them through the lymph nodes as it goes.
Unlike the circulatory system, where the heart creates a ‘beat’ to push/pump the blood around the body, lymph does not have a ‘pump’ - it depends entirely upon movement of the body and moves just one way - out. Hence why so many horses develop 'puffy leg syndrome' if stabled long-term because lymph has to work against gravity, so it requires constant movement by the body and proper breathing in order to move lymph through the lymphatic vessels, and to pass it through the filters in the lymph nodes.
Worst case scenario if lymph remains put? Chronically bloated extremities bursting with stuck lymph, which bring on a cascade of serious health complications. We're talking stagnant lymph, so instead of dynamic lymph on the move clearing out the bad stuff, it becomes stuck, with stuck toxins and waste products, clogging up their only exit route from the body. And when it comes to the body's overall health, stagnation breeds sickness - enter swelling, and congestion known as lymphedema.
So, in order to unclog the lymphatic system and get the lymph flowing again to flush out all the gunk, it's imperative to keep the lymphatic system healthy.
As lymph makes its way to the collection centers (nodes), the vessels carrying it merge, becoming part of a more extensive, denser network of vessels that eventually morph into lymphatic ducts - just like small streams emptying into larger ones and finally winding up in a river. The ducts then deposit lymph into veins for its last hurrah until its final exit through the bladder, bowel, and sweat.
Along the way, the body's stacked with lymph hardware:
- Lymph nodes - serve as checkpoints for mostly dead or dying immune cells that have already done their job fighting infection or are in the process of doing so. They filter the lymph by removing toxins and releasing the cleaned-up lymph back into the tissues. Lymph nodes are the third essential player alongside the liver and kidneys in the body's overall toxin filtration system, and play a vital role in the immune defence system.
- Lymph organs (i.e. tonsils, thymus, spleen) - act as immune cell factories.
- Lymph vessels - weave throughout almost all of the tissues and organs.
- Given that most of the immune system resides in the gut, it should come as no surprise that the GI tract also contains some lymphatic tissue, making it very much part of the lymphatic system too.
Why does lymphangitis affect horses?
Over millions of years the independent horse has evolved from a small, forest-living creature with padded feet, into a graceful, fast, flight athlete, standing on elongated single toes and spending most of its time in constant motion. This continual movement in the horse’s leg is vital for the transport of lymph - quite simply, if the horse doesn't move, neither does lymph.
Cue human involvement and our methods of horse management, as in keeping them stabled for long periods of time without significant turnout, and/or making heavy training demands upon them, and we're on a slippery slope of causing stagnant circulation of lymph in the lymphatic system.
What happens if the lymphatics get blocked?
Inflammation of the lymph vessels, aka lymphangitis, occurs if the lymphatic system is compromised. The lymph vessels become inflamed and blocked, and the legs swell because the system cannot remove fluid from these tissues quickly enough.
The lymphatic system within the horse’s lower legs is also especially vulnerable to damage from wounds and infection. Lymph vessels get damaged and can no longer drain lymph fluid from the affected area. This also means that the body cannot fight infection as well as it can with a healthy lymph system.
If swelling occurs, the limb can literally increase in size by 2-3 times. Yellow fluid may seep from the skin in several places and the horse will be in significant pain and unable to move properly. Infection in the affected area may also cause the body temperature to rise.
The initial pain and swelling usually responds rapidly once addressed, although the puffy effect may linger for a while longer. The not-so-great news is that once a horse has had the condition, lymphangitis is likely to recur, and the horse may suffer from puffy leg syndrome permanently. If your horse spends a lot of time in a stable or is relatively immobile, poor lymphatic circulation can cause further swelling in a previously affected limb, but this will tend to dissipate on exercise.
In a nutshell, movement is absolutely key to a healthy lymphatic system.
- Hydrate - ensure your horse is drinking plenty of water - the lymph system requires a constant supply of fluid to keep it functioning at its best.
- Massage - a great way to encourage natural drainage of the lymph from the tissue spaces in the body – studies show that it can increase the volume of lymph flow by up to 20 times, making it easier for the body to remove toxins.
- Movement - critical to keeping the lymph system open and flowing. When the muscles move, they also help move and pump the lymph within its vessels, even at walk. Also, sweat is one of the major elimination routes of toxins - waste product is eliminated via the sweat glands, which is another reason why movement is so important.
- Dry Brushing - helps increase circulation which helps to boost slower-than-average lymph systems.
- Breathing – I know, stating the obvious really. However, comfortable breathing is really important, because sufficient movement of air through the lungs also helps move and pump fluid through the lymphatic system while providing it with fresh oxygen. Thus if your horse has respiratory issues, keep those airways open.
- Garlic – garlic is a powerful lymphatic cleanser. Add it to feed for the first month of treatment, by which time the building blocks should be in place for a healing effect.
- Stress – keep stress levels down – a happy, balanced system helps decongest the lymph system.
- Pesticides & Processed Food - preservatives, pesticides, herbicides, and food additives like refined sugar, all put strain on the lymphatic system. Consuming chemically treated, highly-processed sugary and fatty foods simply creates an even larger workload for your lymph system and stops it from properly filtering toxins.
- Prescription Drugs - Ultimately, prescription drugs carry toxic residue into the body which suppress the immune system.