Question
My favorite broodmare gets a “big leg” occasionally, and it gets harder and harder to treat with each flare-up, never resolving to its normal size anymore. Is there anything I can feed her that might help this, any nutritional supplement? I’d pretty much sell a kidney for this mare.
Answer
Recurrent cellulitis—often called “big leg”—can be frustrating for both owners and veterinarians as no single treatment works for every horse.
A bacterial infection of the soft connective tissues underlying the skin, cellulitis usually starts as a wound, sometimes so small that it’s barely decipherable and therefore seemingly insignificant. As it happens, the wound only has to be large enough to allow entrance of the offending pathogen, usually a member of the Staphylococcus, Streptococcus, or Escherichia family. In a study of eight horses with cellulitis, all cultured positive for Staphylococcus aureus and, more broadly, this pathogen is implicated in about 60% of all cases of cellulitis.*
As the infection takes hold, the leg will swell considerably—think two, even three, times its normal size—so this looks much different than run-of-the-mill stocking up, which usually affects pairs of legs and resolves with exercise. Because the swelling is severe and the normal contours of the leg disappear, the inflammation is sometimes described as “stovepipe” swelling. The horse will likely experience pain with moderate to severe lameness and may have a fever. Certain environmental conditions, like heat and humidity, can exacerbate the swelling. Without intervention, the swelling can become so great that serum seeps through damaged layers of skin, potentially scalding the hair and forming crusts on the leg.
Cellulitis is usually treated with an aggressive regime of broad-spectrum antibiotics and anti-inflammatories. Other treatments that have yielded inconsistent results include hosing with cold water or standing in ice; topical antimicrobial or cortisone ointments; and long-term antibiotic use. While compression legs wraps or stockings might provide some relief, bandages, such as standing wraps, are counterproductive if applied incorrectly, as some veterinarians find that the swelling simply creeps above the bandage. Affected limbs might never return to normal.
Because of the pain associated with cellulitis, many horses are reluctant to move, but exercise is essential to help promote circulation and to assist in the removal of extraneous fluid from the limb. For this reason, hand-walking several times a day is important for stall-bound horses. Further, all-day turnout is best for horses once healing has progressed.
Supporting hindgut health in the face of antibiotic therapy is always a wise idea, especially for those horses with more sensitive digestive tracts. Choose a research-proven supplement designed specifically to moderate the pH of the hindgut, such as EquiShure. Many veterinarians recommend vitamin E for additional immune support. Whenever possible choose a natural-source vitamin E supplement, like Nano-E, which features nanodispersion technology and superior bioavailability. Anecdotal evidence suggests copper and zinc supplementation may also be beneficial.
*Cooper, H.E., E.J. Davidson, J. Slack, and K.F. Ortved. 2020. Treatment and outcome of eight horses with limb cellulitis and septic tendonitis or desmitis. Veterinary Surgery 50:1542-1552.
