Cellulitis is a bacterial infection of the deep layer of the skin (dermis), and the connective tissues underlying the skin. The most common cause of cellulitis is an infected puncture wound, injection site or even small breaks in the skin.

It can also occur in some cases in which there is no detectable break in the skin. Certain bacterial species (including some Clostridium species), have toxins that break down the connective tissues and aggressively spread through the tissues creating widespread, severe, and sometimes life threatening infection.

These infections usually cause intense pain, swelling and lameness. The severity of lameness means that this process can be confused with joint infection and limb fracture.

This condition can occur anywhere but most commonly is found on the limbs or at injection sites. It is a challenging condition to treat. The cornerstone of treatment is the appropriate antibiotic. Local wound care is important. It is critical for a veterinarian to establish proper drainage of wounds.