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Lymphangitis, also known as big leg disease or stovepipe leg, is a condition in horses involving inflammation of the lymph vessels, most often in the lower limb. [1]
Lymphangitis presents as extreme swelling with rapid onset, resulting in pain in the lower leg, reluctance to bear weight, lethargy, lack of appetite, and sometimes fever.
This condition is caused by bacterial or fungal infection, usually following a wound to the leg. The infection can also result in very painful sores or lumps on the leg and cracking of high-motion skin areas (such as the fetlock). [1]
Seek veterinary care immediately if you suspect your horse has lymphangitis. If left unaddressed, the infection can spread to other organs and cause internal abscesses or sepsis, a potentially life-threatening condition.
Lymphangitis can be difficult to treat and often does not completely resolve. Proper management can keep an afflicted horse comfortable and reduce the risk of complications, but the horse may need to be retired from their athletic career.
The Equine Lymphatic System
The horse’s lymphatic system is similar to the circulatory system.
Whereas the circulatory system transports blood containing nutrients and oxygen to cells, the lymphatic system transports lymph fluid to carry waste products away from cells.
The lymphatic system is crucial for immune function, fluid balance and the filtration of water products from around tissues.
Lymph fluid travels through a system of lymph vessels to lymph nodes around the body. These vessels have one-way valves that prevent fluid from back-flowing down the legs due to gravity.
Lymph nodes contain white blood cells called lymphocytes, which function as part of the immune system. Lymphocytes detect and destroy dangerous pathogens, such as bacteria or viruses. [3]
Movement of Lymph Fluid
Your horse’s heart pumps blood through their circulatory system, but the lymphatic system does not have an active pump.
Instead, lymph fluid circulation depends on indirect mechanisms such as muscle contraction, movement of the limbs, and pulsation of the adjacent blood vessels.
Horses that stand for long periods without adequately moving their limbs can experience pooling of lymph fluid in their legs. This is temporary and usually resolves after exercise.
However, in cases of lymphangitis, the lymph vessels become inflamed and lose their ability to adequately transport lymph fluid. Continued pooling within the limbs can cause enough damage to the lymphatic vessels to block fluid drainage even with movement.
Damaged lymph vessels often do not heal well, making lymphangitis a disease with a poor prognosis. [4]
Lymphangitis in Horses
Lymphangitis is caused by bacteria entering the lymphatic system, usually via a wound to the lower limb. Bacteria travel through abrasions into the deep layers of the skin, entering the lymphatic vessels.
After detecting an infection, the horse’s immune system transports infected lymph fluid from the leg to the lymph nodes. The lymph nodes are responsible for clearing infection from the fluid, but they can become infected themselves.
Infected lymph vessels become swollen, damaged or blocked, causing lymph fluid to pool in the limb. As fluid accumulates, the leg experiences progressive swelling.
The skin becomes taut and may crack, forming lesions (ulcers) that seep clear, yellowish lymph fluid. Crusty yellow flakes of dried lymph may form on the skin. [7]
These open wounds can exacerbate the condition, allowing more bacteria into the horse’s already compromised system.
What's your top priority with your horse's health?
What's your top priority with your horse's health?
Causes of Lymphangitis
Lymphangitis is caused by pathogens entering the horse’s body through a skin laceration (wound or abrasion).
It may develop following an injury, cut, puncture wound, insect bite, injection, or secondary to another skin condition such as mud fever. [12]
The most common bacteria types associated with lymphangitis in horses include:
- Corynebacterium pseudotuberculosis
- Staphylococcus aureus (staph infection)
- Streptococcus
- Escherichia coli [1][7]
Epizootic lymphangitis is another form of lymphangitis caused by a fungal infection from Histoplasma farciminosum. [9]
These pathogenic agents thrive in wet, muddy conditions. Horses standing in mud for long periods or horses with damp legs are susceptible to lymphangitis because the skin’s natural oil barrier becomes compromised.
Lymphangitis Symptoms
Lymphangitis typically affects a single hind limb at a time, resulting in swelling in the lower (distal) limb.
Symptom onset occurs rapidly in horses with lymphangitis. Some clinical signs of this condition include:
- Extreme swelling of the lower limb
- Heat in the limbs
- Pitting edema (a fingerprint remains in the skin when you press on the swollen area)
- Cracking or splitting of the skin
- Crusty yellow discharge that can scald the skin
- Skin that is extremely painful and hot to the touch
- Reluctance to bear weight or move the limb
- Inappetance (lack of appetite)
- Fever
- Lethargy
- Dark, wart-like growths that are painful and bleed profusely when peeled off
If your horse displays any of these signs, consult with your veterinarian to determine if your horse has lymphangitis or another related condition. [7]
If swelling continues unchecked, blood flow to the limb can be compromised enough to cause the hoof capsule to come off. The horse may require euthanasia. [11]
Ulcerative Lymphangitis
Ulcerative lymphangitis (pigeon fever) is a rare but severe case of lymphangitis that affects more than just the lower limbs. [1]
This disease is caused by the introduction of Corynebacterium pseudotuberculosis or Staphylococcus aureus bacteria into the lymphatic system.
Ulcerative lymphangitis results in abscesses on the lower limbs and internal organs, as well as swelling and abscessing in the chest and neck. [1][8]
The lower limbs become lumpy with small abscesses that open and drain pus-like fluid.
This infection can be fatal; 30 – 40% of horses that suffer from internal abscesses do not survive. [1]
Stocking Up vs. Cellulitis vs. Lymphangitis
Many horse owners confuse stocking up and cellulitis with lymphangitis.
All three conditions have similar presentations and are associated with swelling to the lower limbs, but only lymphangitis is caused by damage to the lymphatic system.
Stocking Up
Stocking up, also known as stagnation edema, refers to a buildup of lymphatic fluid in the horse’s lower limbs due to a lack of movement.
Stocking up is a direct result of sustained inactivity; once the horse starts moving the symptoms resolve. This temporary swelling does not require antibiotic treatment and is not usually painful to the horse.
Pressure or standing bandages are used to reduce swelling when physical activity is not possible, by compressing the tissue to prevent lymph accumulation between the cells. [6]
While stocking up is usually temporary and minor, if left unaddressed the swelling can worsen and damage the lymph vessels, potentially leading to lymphangitis. [2]
Cellulitis
Cellulitis involves an infection of the horse’s subcutaneous soft tissues (tissues under the skin).
It occurs when bacteria, commonly of the Streptococcus family, enter into the deep layers of the skin, damaging blood vessels and allowing leakage of lymph fluid into the area.
Cellulitis presents as sudden swelling of the horse’s limb. While this infection can occur anywhere on the horse’s body, it is most often seen in the lower legs.
Horses with cellulitis experience extreme pain in the affected area and are often very lame, sometimes refusing to weight-bear. In addition, horses may have a fever and may be reluctant to eat.
In horses with cellulitis, the lymphatic vessels are not usually damaged. Once the infection is treated with anti-inflammatories and antibiotics, the swelling and discomfort usually resolve.
If left untreated, cellulitis can lead to permanent damage to the lymph vessels, resulting in lymphangitis. Cellulitis can also lead to sepsis, a deadly systemic infection. [5]
Lymphangitis
Lymphangitis is the most serious of the three conditions that commonly cause leg swelling in horses.
Like cellulitis, lymphangitis usually results from a bacterial infection that causes swelling and impairs the flow of lymph fluid through the lymphatic system.
Unlike cellulitis, the main feature of lymphangitis is inflammation and damage to the lymphatic vessels and not the subcutaneous soft tissues.
Like cellulitis, lymphangitis is extremely painful for the horse. Lymph fluid accumulates in the lower limb, causing severe swelling and stretching of the skin and tissues within the leg.
Unlike cellulitis, lymphangitis is difficult to treat and often has long-term consequences. Once damaged, lymphatic vessels can develop scar tissue that impedes lymph flow.
Even after the bacterial infection is treated, the horse may experience recurrent swelling and pain in the limbs. [1]
In some horses, lymphangitis repeatedly occurs once the initial infection has resolved. If your horse experiences repeated episodes of lymphangitis, your veterinarian may diagnose sporadic lymphangitis. [2]
Treatment
Your veterinarian will diagnose lymphangitis upon observation of clinical signs and ruling out other causes of leg swelling.
Treatment of a horse with lymphangitis centers on two goals:
- Control the pain and inflammation
- Treat the bacterial infection
Lymphangitis has a guarded prognosis, which means the outcome is uncertain and some horses experience on-going complications.
Control Pain and Inflammation
Horses with lymphangitis experience a lot of pain and often do not want to move. This makes it difficult to resolve the swelling as lymph drainage from the legs relies on movement.
To encourage the horse to move, your veterinarian will administer medications to alleviate pain and inflammation in the limb.
Medications
Your veterinarian may prescribe non-steroidal anti-inflammatory medications (NSAIDs), such as phenylbutazone (Bute) or flunixin meglumine (Banamine), to make the horse more comfortable.
Cold hosing of the limb may also provide some relief, so long as the leg is thoroughly dried after water application. A damp leg will only encourage bacteria to propagate and worsen the infection.
Your veterinarian may also administer intravenous dimethyl sulfoxide (DMSO) or corticosteroids to reduce inflammation. Some veterinarians may treat with diuretics to draw moisture from the horse’s tissues and increase urine output. [7][9]
Draining Abscesses
If abscesses or cysts are present under the skin, your veterinarian may lance and drain them. Draining abscesses will relieve pressure and improve your horse’s pain.
Wrapping with Bandages
It may be tempting to apply standing or pressure bandages to your horse’s leg, but this may cause more harm than good. Horses in the acute phase of lymphangitis will continue swelling above the pressure bandage, potentially restricting blood flow to the lower limb.
Once the horse has progressed to the chronic phase of lymphangitis, wrapping can decrease swelling and pain. [7][9]
Promoting Lymph Flow
After addressing the horse’s pain, encourage them to move around as much as possible to pump lymph fluid up from the limb. Hand walking, turnout, and gentle exercise can help reduce swelling.
Some owners recommend lymphatic massage for the lower limb, but this may be difficult if the leg is painful to the touch. Research is not available to evaluate the efficacy of massage therapy for lymphangitis in horses.
Treating Bacterial Infection
Your veterinarian will recommend the best course of antibiotic medications to treat the bacterial infection causing lymphangitis in your horse.
Your veterinarian may take a bacterial culture from the horse’s leg by swabbing any open sores in the skin and submitting the sample to a laboratory for identification.
Injectable antibiotics (i.e. injectable penicillin, Excede®) may be prescribed for immediate treatment followed by extended use of oral antibiotics. [1][10]
If the swollen limb has open wounds, your veterinarian may suggest cleaning the leg with an antiseptic solution to eliminate bacteria. Provide the horse with pain relief and/or sedation before cleaning, as even light touch to the area can be incredibly painful. [1]
Long-Term Management
Lymphangitis is a serious condition that rarely goes away completely. The horse’s lymph vessels may be permanently damaged and the horse may experience ongoing swelling.
While the limb never returns to its former state, horses can remain comfortable with careful management to support the limb and prevent flare-ups. [7][9]
- Exercise the horse daily
- Avoid unnecessary stall rest
- Treat all leg wounds, no matter how small, by thoroughly cleaning the region and applying antibiotic ointment
- Call your veterinarian immediately if you notice any swelling or lameness
- Stable the horse with magnetic or ceramic wraps which may encourage lymphatic movement
Frequently Asked Questions
Here are some frequently asked questions about lymphangitis in horses:
Lymphangitis in horses is inflammation and damage within lymphatic vessels, which normally move excess fluid away from tissues in the limbs. When bacteria enter through a cut, scrape, or other skin injury, these vessels become swollen and blocked, causing rapid fluid buildup in the leg. Horses with lymphangitis often develop severe swelling, pain, heat, and reluctance to move, making immediate veterinary treatment important.
Lymphangitis develops when bacteria or fungi enter through damaged skin and spread into lymphatic vessels. Small wounds, insect bites, punctures, mud fever, and injections can all create entry points for infection. Wet, muddy conditions increase risk because constant moisture weakens the skin’s natural protective barrier. Common bacteria linked to lymphangitis include Streptococcus, Staphylococcus aureus, and Corynebacterium pseudotuberculosis.
Signs of lymphangitis include sudden swelling in one lower limb, severe pain, heat, and reluctance to bear weight. Many horses also develop fever, lethargy, loss of appetite, and sensitivity when the leg is touched. Skin may crack or leak yellowish fluid as swelling increases. Rapid onset and extreme swelling are major warning signs that separate lymphangitis from milder causes of leg edema.
Lymphangitis most often affects a single hind leg and usually develops very quickly once infection enters lymphatic vessels. Swelling commonly starts in the lower limb and may spread upward as fluid accumulates. Affected legs often appear dramatically enlarged within hours and can become extremely painful. While one leg is most common, severe infections may spread further if treatment is delayed.
Mud increases risk of lymphangitis because prolonged moisture softens and damages skin, making it easier for bacteria to enter through small cracks or abrasions. Horses standing in wet paddocks or muddy turnout areas often develop compromised skin around the lower limbs. Damp conditions also support growth of bacteria associated with skin infections and lymphatic inflammation.
Lymphangitis causes significant pain because swelling stretches tissues and inflamed lymphatic vessels lose their ability to drain fluid properly. Many horses become severely lame and resist moving or placing weight on the affected leg. Skin can feel hot and tight, and even gentle handling may cause discomfort. Pain management is an important part of treatment because movement supports lymph drainage from the limb.
Lymphangitis often leaves lasting damage because inflamed lymphatic vessels do not heal well once scar tissue develops. Even after infection improves, some horses continue experiencing recurring swelling or periodic flare-ups in the affected limb. Long-term management often focuses on reducing inflammation, encouraging movement, and preventing new skin injuries that could trigger another episode of infection and swelling.
Stocking up is temporary fluid accumulation caused by inactivity, while lymphangitis involves infection and damage to lymphatic vessels. Horses with stocking up usually improve after movement and rarely show pain or fever. Lymphangitis causes rapid swelling, heat, severe discomfort, and systemic illness that does not resolve with simple exercise alone. Veterinary treatment is often necessary to control infection and inflammation.
Cellulitis affects soft tissues under the skin, while lymphangitis mainly damages lymphatic vessels responsible for fluid drainage. Both conditions can cause sudden swelling, pain, and lameness, which makes them difficult to distinguish without veterinary evaluation. Horses with cellulitis often recover once infection resolves, but lymphangitis can leave permanent vessel damage that leads to chronic swelling and repeated flare-ups.
Lymphangitis can become life-threatening if infection spreads beyond the limb and causes sepsis or internal abscesses. Severe swelling may also reduce blood flow enough to damage tissues within the leg and hoof. Horses with ulcerative lymphangitis face additional risk because bacterial infection may spread into internal organs, chest tissues, or lymph nodes throughout the body.
Treatment for lymphangitis focuses on controlling infection, reducing pain, and improving lymph drainage from the affected limb. Veterinarians commonly prescribe antibiotics along with anti-inflammatory medications such as phenylbutazone or flunixin meglumine. Gentle movement, turnout, and hand walking encourage fluid circulation once pain is controlled. Horses with abscesses may also need drainage and wound cleaning to reduce pressure and bacterial contamination.
Exercise can reduce swelling from lymphangitis because muscle movement helps push lymph fluid upward through damaged drainage vessels. Gentle walking and turnout are commonly used after pain is controlled enough for the horse to move comfortably. Horses standing still for long periods often experience worse swelling because lymphatic circulation depends heavily on movement rather than a pumping organ like the heart.
Horses can recover enough from lymphangitis to remain comfortable, but many continue dealing with some degree of chronic swelling or sensitivity in the affected limb. Prognosis depends on how quickly treatment begins and how much damage occurs within lymphatic vessels. Some horses return to regular activity, while others experience repeated episodes that limit long-term athletic performance.
Summary
Lymphangitis is a painful and potentially serious condition caused by infection and inflammation within the lymphatic vessels of a horse’s limb. Rapid swelling, extreme discomfort, and impaired lymph drainage make early veterinary care essential, and long-term management is often required because damaged lymph vessels rarely heal fully.
- Lymphangitis occurs when bacteria or fungi enter through a wound and inflame lymph vessels, causing severe swelling and pain
- Damage to lymphatic vessels restricts fluid drainage, leading to pooling, cracking skin, fever, lethargy, and possible systemic infection
- Diagnosis and treatment rely on pain control, anti-inflammatories, antibiotics, abscess drainage, and careful movement to promote lymph flow
- Chronic cases often require ongoing management, including daily exercise, wound care, prompt treatment of flare-ups, and supportive wraps
- Lymphangitis is distinct from stocking up and cellulitis because it involves direct lymphatic vessel damage and has a more guarded prognosis
References
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