Understanding lymphangitis in horses and how to avoid it

Lymphangitis is a potentially serious equine condition caused by bacterial infection of the lymphatic system. Here’s what you need to know...

What is lymphangitis in horses?

Lymphangitis is a potentially serious condition caused by a bacterial infection. It can cause permanent damage to the limbs and strikes indiscriminately – any breed and any age can be affected.

The condition has three forms: sporadic, ulcerative and epizootic.

The sporadic form is the one we usually see in the UK, as well as the odd ulcerative case. Epizootic lymphangitis, endemic in Africa, has not been seen here since the 1970s.

The lymphatic system is a complex network of fine vessels that run parallel to the arteries and veins. These contain lymphatic fluid, or lymph, which drains fluid away from the limbs.

These vessels are very fine-walled structures and rely on tiny valves to stop the backflow. At various points there are lymphatic glands, which help to filter the fluid.

If the lymphatics become blocked this 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 on the leg.

A horse with lymphangitis will typically have a swollen hindlimb that is hot and painful to touch – it is rare that the forelimbs are affected – and a high temperature, often between 104 °F and 106 °F (40-41 °C), plus severe lameness.

Lymphangitis may come on quickly. The most severe of cases can quickly deteriorate into the ulcerative form, where multiple abscesses can burst through the skin, releasing pus, serum and lymph.

Treatment for lymphangitis in horses

Early intervention and prompt treatment is essential to prevent irreparable damage.

A swab may be taken from the wound or skin (especially if serum is weeping) for bacterial culture and sensitivity; this allows the targeted use of antibiotics against sensitive bacteria. The choice of antibiotic is important because of the increase in bacterial resistance; systemic, injectable antibiotics are often used for a quicker effect and to ensure the full dose is received and there is no reliance on a sick horse eating oral antibiotics.

It is vital to give antibiotics immediately as well as a non-steroidal anti-inflammatory drug (NSAID) such as flunixin or phenylbutazone (“bute”). In severe cases steroids may be used initially.

Topical skin treatment of the wounds, dermatitis or scabs (using antibacterial or antiseptic washes and creams) is important to prevent ongoing infection and bandaging (with thick padding beneath) is important to help reduce the swelling. It is vital to use a large amount of thick padding such as cotton wool or cotton wadding under the bandage.

Exercise is very important to help improve the circulation thereby reducing swelling; although the initial few steps can be very painful there is usually a rapid improvement.

Other treatments may include diuretics such as frusemide to reduce the fluid, potassium iodide solution (orally for dermatitis) or intravenous DMSO.


Prevention can be more difficult, particularly once lymphangitis has occurred and caused some permanent scarring. Obviously hygiene and cleanliness of the skin has got to be scrupulous; any wounds must be addressed immediately.

How to minimise the chance of your horse suffering from lymphangitis

  • Keep the horse in regular (daily) exercise – lymphangitis most often affects animals that are not in active work or are experiencing a period of rest
  • Treat any wounds immediately, no matter how minor they might seem, by cleaning with an effective dilute antiseptic
  • Apply a barrier wound cream, as recommended by your vet, to keep infection out of small wounds
  • Call your vet at the first sign of limb swelling. Early intervention within 12hr of the first signs appearing is crucial and means you may limit the damage

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