You open the stall door one morning and are greeting by a horse sporting a very swollen leg. What is causing it? As big and strong as horses are, their legs are quite sensitive and subject to a variety of problems. A horse’s lower legs may swell for several reasons: stall confinement following intense exercise; lack of exercise; obesity; over-feeding or a diet too high in protein; or an allergic reaction. This kind of swelling is usually temporary, causes no discomfort beyond some stiffness, and gets better or disappears after exercise. Both hind legs or all four legs are most often affected. Stable bandages, regular turnout, rubbing the legs with liniment or leg brace after exercise, and hosing the legs with cold water for 15-20 minutes may be helpful if your horse suffers occasionally from swollen legs, often called filled legs or stocking up.

Cellulitis and lymphangitis are much more serious problems. Cellulitis is an inflammation of the skin and the soft tissues directly underneath. Lymphangitis develops when the inflammation spreads to deeper tissues and vessels that move lymph through the body. (Lymph is a clear, yellowish fluid containing white blood cells that helps the body regulate fluid balance and fight infection.)

Cellulitis and lymphangitis are usually caused by a bacterial infection that has entered the horse’s body through a break in the skin. This may be a tiny puncture such as an insect bite that you can’t even see. Other causes include softening of the skin from being exposed to water or moisture too long; serious cases of stocking up; or bruising.


Symptoms are generally the same for cellulitis and lymphangitis and can begin as late as 2-3 weeks after an injury. Symptoms often begin in one leg, but may involve two or all four legs in some cases. The horse’s leg swells rapidly to the hock or knee, with swelling sometimes as high as the stifle or elbow. The lower part of the leg may be two to three times its normal size. The horse is seriously ill, with a fever of 102 – 105° F (38.8 – 40.5° C) or higher, shivering, and has rapid pulse and respiration, loss of appetite, pain when the affected limb is touched, and severe lameness. Yellowish-clear serum may ooze from the most swollen areas.

In the case of ulcerative lymphangitis, the swollen lymph vessels can be felt as cords running up the inside of the leg, and yellow-green pus escapes from abscesses under the skin. This serious condition might signal a rare form of pigeon fever, a disease caused by bacteria with the tongue-twisting name Cornybacterium Pseudotuberculosis. While previously known only in the southwestern US, pigeon fever has been spreading, with several cases reported in the Okanagan Valley region of BC over the past couple of years. This form of lymphangitis is contagious, spread by flies and ticks, or contact with pus from a draining ulcer, contaminated bedding, soil or other material. Your vet can take a swab of the pus to determine if your horse’s infection is caused by C. Pseudotuberculosis or some other more common bacteria.


If your horse shows signs of cellulitis or lymphangitis, call your vet immediately. He will almost certainly prescribe antibiotics for the infection and an anti-inflammatory such as phenylbutazone or Banamine® for the swelling and pain. Further recommended treatments include:

• mild exercise (lungeing or hand-walking) 15-20 minutes several times per day;

• cold-hosing 15-20 minutes several times per day for the first 48 hours

• alternating cold and hot compresses after the 48-hour mark;

• draining any abscesses and cleansing the area with an antiseptic such as proviodine detergent or Hibitane®;

• gentle upward massage of the swollen limb to stimulate circulation;

• application of a medicated poultice or DMSO*;

• stable bandages to compress the tissues (make sure the leg is dry, though).

(*Note: Never apply poultices, DMSO or clay to broken skin.)

If you’re into alternative medicine, you might look at clay* poultices, homeopathy or even acupuncture as well as traditional treatments. Speak to your vet or an expert in holistic medicine. Keep your horse’s stall clean, and cut back his grain until he goes back to work. Lastly, always wear latex gloves if you treat a horse suffering from one of these conditions, especially ulcerative lymphangitis.

Simple cases of cellulitis or lymphangitis may take several weeks to heal. Severe or untreated cases can become chronic (constant) or recurrent (coming back again), and the tissues under the skin of the affected leg may remain permanently thickened. In the occasional worst-case scenario, the condition can be fatal.

There are a few things you can do to minimize the risk; make sure your horse has:

– proper nutrition

– a healthy weight

– a clean stall with fresh bedding

– regular exercise

– minor injuries treated right away

– clean and dry legs

Prompt, effective care is the key to recovery. The good news is that most horses recover completely and return to their usual horsey activities!