Cellulitis is a diffuse bacterial infection of the skin and subcutaneous tissues than dissects rapidly and extensively through tissue planes, resulting in significant swelling and localized and regional pain. Any entry point through the skin from a wound or even a mild abrasion, scrape, or “scratches” can lead to infection. Blunt trauma that bruises deep tissues sets up conditions for bacterial growth. In some cases, there is no obvious wound or trauma associated with cellulitis.
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Limb cellulitis typically occurs acutely—the horse seemed fine but then is suddenly lame with rapidly developing swelling that extends up and/or down the leg. The swollen limb feels warm to touch and the horse expresses extreme discomfort from even the lightest touch of the infected area, and is lame in that leg. There is usually pitting edema—pressing in with your finger leaves an indentation due to excess fluid accumulation within the tissues. In addition to pain and swelling, cellulitis may cause a horse to go off feed, feel lethargic, have an elevated heart rate, fever, and serum may ooze from the skin of the swollen leg. In comparison, simple “stocking up” usually occurs in more than one leg, is non-painful, and the horse doesn’t notice a problem.
Cellulitis has the potential to be life-threatening, so it is important to reach out for professional veterinary help immediately. A thorough examination, ultrasound, and bacterial culture are some diagnostic tools used to identify an appropriate course of antibiotics and anti-inflammatory medications for a successful resolution.
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The best cure for cellulitis is prevention. Regularly monitor your horse for any break in the skin. No matter how minor a wound may appear, apply general first aid practices by trimming or shaving away the hair around the wound, and then scrubbing with antiseptic soap while attempting to determine how deep the injury might be. Apply antibiotic ointment to the wound and then bandage. Discuss your findings with your vet to determine if professional veterinary care should be provided sooner rather than later.