July: A Skin-Deep Situation

Case of the Month – A Skin-Deep Situation

Abby’s owner called when she noticed Abby’s right hind was swelling up.  Shortly thereafter, the swollen leg started forming draining abscesses and the mare was very lame.  Cellulitis is a bacterial infection of the deeper layers of the skin following some sort of disruption of the skin such as a cut or dermatitis.  It is usually caused by opportunistic bacteria on the horse’s skin or environment that invade when given the chance.  It is very painful, often causes a fever and requires antibiotic treatment (sometimes prolonged).  Though swelling, heat and pain are always present, abscessation, pustules and draining tracts are unusual.  Abby was placed on a much stronger antibiotic than is usually required for this reason.  Cold hosing, handwalking/lunging and meticulous wound care and bandaging are also always important adjunctive therapies.  Despite the diligent care, Abby still required a prolonged course of Excede.  A month after the cellulitis first developed Abby was finally sound again, but still not fully healed. One of the abscess tracts was cultured showing two nasty families of bacteria with resistance to a number of commonly utilized antibiotics in equine practice.  Abby was placed on an uncommon antibiotic, based on culture results, which finally cleared the infection. Unfortunately she developed exuberant granulation tissue (proud flesh) from the two largest abscess sites that required some surgical debridement. Several months later this leg is thickened with scar tissue under the skin but no infection or proud flesh; resolution of this very complex cellulitis relied on antibiotic choice guided by wound culture and aggressive trimming of the secondary proud flesh, as well as a very dedicated owner.