Sterile Nodular Panniculitis

Sterile nodular panniculitis is a condition in which the layer of fat beneath the skin becomes inflamed, forming firm lumps or nodules that can appear anywhere on the body. The inflammation occurs without infection — the word sterile refers to the absence of bacteria or other infectious agents. The immune system appears to be reacting to the fat tissue itself, though the precise trigger is not always clear. Owners often notice one or more raised, firm areas under the skin that may feel warm, appear reddened or discoloured, and sometimes open to discharge an oily or fatty material. These nodules can develop gradually or appear quite suddenly, and they may occur as isolated lumps or in clusters. The condition can affect dogs of any age or breed, though certain patterns have been observed in specific groups. This page explores the signals that may prompt consideration of sterile nodular panniculitis, the mechanisms that drive inflammation in the fat layer, the investigations used to distinguish it from other causes of skin lumps, and the approaches available for managing the condition over time.