CONDITION
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.
Why this matters now
Sterile nodular panniculitis can appear at any age, though it tends to be recognised most often in young to middle-aged dogs. Certain breeds, including Dachshunds, Miniature Poodles, and some terrier breeds, appear to develop the condition more frequently, though the reason for this pattern is not fully understood. In some cases, nodules appear following trauma to the skin or subcutaneous tissue, or after periods of stress or illness, though many instances arise without any obvious preceding event. Nutritional factors, particularly vitamin E deficiency, have been associated with some forms of panniculitis, though sterile nodular panniculitis often occurs in the absence of any identifiable dietary insufficiency.
The condition may present as a single nodule that remains stable for weeks or months, or multiple nodules may develop over a short period. Some nodules enlarge gradually, whilst others remain static or even regress without intervention. In a proportion of cases, nodules soften, rupture, and drain an oily or greasy material before healing, leaving behind scarring or areas of altered pigmentation. The course varies considerably between individuals, with some experiencing a single episode and others developing recurrent nodules over months or years.
Signals & patterns
Early signals
Firm lumps beneath the skin
One or more raised, firm areas may be felt when stroking the dog, often on the trunk, limbs, or neck. These nodules sit within or just beneath the skin layer and may feel distinct from the surrounding tissue.
Warmth over the area
The skin overlying the nodule may feel warmer than adjacent areas, reflecting the inflammatory process occurring in the fat layer underneath. The warmth can be subtle and may not be present in all cases.
Redness or colour change
The skin above the nodule may appear pink, red, or purple, or may show darker pigmentation in animals with more heavily pigmented skin. The colour change reflects increased blood flow and inflammation in the tissue.
Discomfort on touch
Some dogs show sensitivity when the area is handled, flinching or turning towards the site when it is pressed. Others tolerate examination without obvious discomfort, even when nodules are quite inflamed.
Solitary or clustered nodules
The lumps may occur as a single isolated nodule or in groups, sometimes appearing symmetrically on both sides of the body. The distribution can offer clues to the underlying pattern, though considerable variation exists.
Later signals
Softening and drainage
As nodules mature, they may soften and develop a fluid-filled quality. The overlying skin can ulcerate, releasing a thick, oily, or yellowish discharge that may have a greasy texture consistent with liquefied fat.
Scarring or hair loss
Areas where nodules have ruptured and healed often leave behind permanent scarring, changes in skin texture, or patches where hair no longer grows. The skin may appear thickened, puckered, or discoloured.
Recurrent new nodules
In some individuals, new nodules continue to appear over weeks or months, sometimes at sites distant from the original lesions. This pattern suggests an ongoing process rather than a single localised event.
Generalised signs
A proportion of dogs develop lethargy, reduced appetite, or mild fever alongside the skin changes, particularly when multiple nodules are present or inflammation is widespread. These signs reflect a more systemic inflammatory response.
Click to read about the biological mechanisms
How this is usually investigated
Options & trade-offs
Last reviewed: Invalid Date ·