Cellulitis is an infection of the deep layers of the skin and is actually fairly common. The major symptoms are persistent heat and swelling, sometimes with pain and lameness. Because it is usually found on the legs, cellulitis can be confused with a joint or tendon/ligament injury. However, the swelling occurs only on one side of the cannon bone or around the cannon bone (not just over the tendons) or extends beyond the limits of the joint capsule.
Cellulitis usually starts through something simple, like a scrape or scratches. Skin reactions from liniments and paints can also evolve into a cellulitis. Even a rap on the cannon bone with no visible breaks in the skin may get it started. Cellulitis often occurs and/or worsens in legs with a pre-existing inflammatory problem.
Even though cellulitis is not particularly serious, it can be frustrating to treat. There virtually is no way to obtain cultures and identify the infecting organisms. The skin usually does not open and drain (although it may crack), and you often can’t find the small injury that started the process. The associated inflammation seems to play a key role in allowing the infection to spread, but even anti-inflammatory therapy can be tricky with cellulitis.
Basic treatment involves intensive local treatment to cut inflammation. This means cold — lots of it. For cellulitis, cold-water hosing or ice wraps are the way to go (avoid soaking). For ice wraps, we prefer Dura-Kold wraps (800/541-7199) as they keep the leg dry and the lining can be easily disinfected by wiping with alcohol between uses. Areas of broken skin should be gently cleansed once or twice a day. Treat the skin with a mixture of antibiotic-antifungal cream, such as the antibiotic products we’ve discussed in the scratches story on page 8 and either Lotrimin or a generic antifungal. Do not use heavy, oil-based products. You need a cream that can be applied lightly and sinks in, such as aloe. Apply at least two times daily.
Topical treatment alone won’t get the job done in stubborn cases. Most vets start with injectable penicillin or oral trimethoprim-sulfa. Gentamicin can be added, if needed, or a switch may have to be made to tetracycline, erythromycin, chloramphenicol or a cephalosporin. Cases that worsen on antibiotics may need a systemic antifungal drug. Wrapping may worsen cellulitis because it traps heat in the leg. Actual wounds or skin breaks can be wrapped, if necessary, but leave the rest of the leg open.
Keep the stall meticulously clean (straw is preferred over sawdust/shavings). Light exercise and turnout are also beneficial in reducing swelling and improving circulation. NSAIDs should be used with caution, as they may enhance inflammatory processes while depressing the production of antibodies.
Stop them immediately if there is no improvement or a worsening.