Cellulitis is a generalised infection of the subcutaneous tissue underneath the skin. It usually involves the lower half of the limbs and is often only in the one leg.
Horses usually present with lameness and a history of sudden onset of limb swelling. Lameness is variable but typically is moderate to severe. On clinical exam, the horse may have a temperature and the leg is characteristically hot and painful to touch. In severe cases, a yellow/orange serum may ooze from the swollen skin.
Primarily cellulitis is caused by bacteria entering the skin, usually through a cut, abrasion, or break in the skin (this break is not necessarily visible) resulting in a swelling that usually begins near the source of infection but will rapidly involve the entire lower limb.
The most common bacteria culprits are the Staphylococcus and Streptococcus species. These bacteria are part of the normal flora of the horse’s skin which normally do not cause infection while on the outer surface of the skin.
Treatment varies depending on the severity of the cellulitis and prompt treatment under the guidance of a veterinarian will significantly affect the outcome. Antibiotic therapy will be initiated and often a long course is required to completely resolve the infection. Non-steroidal anti-inflammatories are also important to control the inflammation and pain. Adjunctive therapy involves cleaning the wound, cold hosing, applying poultices and mild exercise.
Recovery depends on the how quickly the condition is recognised and the severity of the cellulitis. The swelling may take a long time to subside in severe cases. Complications can include infection of important structures, skin sloughing and laminitis in the supporting limb where lameness has been severe and ongoing.
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