20/09/2023
Lymphangitis
Lymphangitis is a painful and potentially serious condition that affects (usually) the hind limbs of your horse.
There are 3 types of Lymphangitis
- [ ] Sporadic ( easily the most common form seen in the uk)
- [ ] Ulcerative
- [ ] Epizootic (not seen In the uk since the 1970’s)
First let’s look at what the lymphatic is and what it does.
The lymphatic system is one of the unsung heroes of any mammals body, the horse is no different. Without its lymphatic system the horse would quickly become overrun with bacteria and viruses and the circulatory system (its blood) would become dirty and clogged.
In its most basic form the lymphatic system cleans, monitors and renews many of the components of blood and is a vital first line of defence against invading pathogens.
The lymphatic system is not connected to the heart so it relies on the movement of tissue and changes in pressure to keep the fluid flowing, here lies our first flaw in the system for the horse which I will come back to later.
All along the system there are many lymph nodes, these are tiny bean shaped lumps of tissue that essentially monitor and clean the lymph fluid as it travels through the lymphatic system before it’s finally returned to the circulatory system via the thoracic duct at the base of the equine neck. These lymph nodes are vital to the system, the lymph fluid slows down and becomes concentrated on entering each node and it can tend to cause bottlenecks in the system, a human has around 600 lymph nodes compared to around 8,000 in the horse, here lies the second problem with horses.
Horse problems with the lymphatic system.
The thousands more lymph nodes that the horse has tends to create bottlenecks and a general tendency to slow the system down, this, along with the fact that the horse doesn’t not have any muscles in the lower legs and thus, nothing to help squeeze the lymph fluid up the leg (against gravity) causes it to pool in the lower limb, especially in older horses and horses that are stabled for long periods of inactivity.
‘Stable fill’
This is when the lower legs appear swollen after being stabled for a few hours or days, often when the horse is walked or turned out the swelling disappears, this is simply a inability of the lymphatic system to drain for the reasons discussed above and is NOT Lymphangitis.
Lymphangitis
Lymphangitis means inflammation of the lymphatic system, usually caused by an infection. The Bacteria responsible is usually streptococcal or streptococcus (strep A).
It can cause permanent damage to the limbs and strikes indiscriminately, any breed and age can be affected.
If the lymphatic system becomes blocked it can cause a dramatic, rapid and painful swelling of the affected area, the bacteria concerned usually gain entry to the lymphatic system via a small cut or abrasion, a horse with Lymphangitis will have a swollen hindlimb that is hot to the touch, a high temperature, often between 40-41 degrees Celsius and severe lameness. In sporadic Lymphangitis the forelimbs are rarely affected.
Summary
Lymphangitis can come on quickly and the more severe cases can quickly deteriorate into the ulcerative form where multiple abscesses can erupt through the skin, releasing pus, serum and lymph.
Therefore,
Veterinary assistance should be sought immediately if this condition is suspected in any form
