Sterile Nodular Panniculitis in Dogs and Cats

Panniculitis is a rare condition in which the layer of fat under the skin, which provides warmth, protection and energy to the body, becomes inflamed. While it may be caused by an infection with bacteria, fungi or other organisms, sterile nodular panniculitis is a descriptive term for an inflammation of the fat cells that does not involve infectious agents. In most cases, the exact cause is not known.

The inflammation results in bumps on the skin surface that can be soft or firm, and are sometimes painful. The bumps can rupture, releasing an oily discharge that may be clear, yellow-brown or bloody. Most pets with sterile nodular panniculitis are treated with drugs designed to modify the immune system, such as steroids, but Vitamin E may also be helpful.


Panniculitis is an uncommon condition in dogs and cats that is characterized by inflammation of the fat-containing tissue just under the skin, which results in nodules, or bumps, on the skin surface. In some cases, the inflammation is brought on by an infection with bacteria, fungi, or other organisms.

Sterile nodular panniculitis is a descriptive term for lesions that do not involve an infectious agent. It may be caused by an injection, such as a vaccine, trauma, systemic illnesses such as pancreatitis or autoimmune diseases, or vitamin E deficiency. Drug reactions have also been implicated in the sterile form of panniculitis. The majority of sterile cases, however, are classified as idiopathic, meaning the cause is unknown.

Symptoms and Identification

With sterile nodular panniculitis, single or multiple nodules of varying size and consistency will appear just under the skin. The head, neck, chest and abdomen are more commonly affected than other parts of the body. Though unsightly, particularly when they eventually break open (fistulate) and drain an oily, clear, yellow-brown or bloody fluid, they may or may not cause the animal discomfort.

Diagnosis is achieved with skin biopsies along with cultures to rule out infection. It’s important, also, to evaluate the pet for evidence of recent drug administration, vaccination, or predisposing disease like pancreatitits or autoimmune conditions.

Affected Breeds

Dachshunds appear to be predisposed. German Shepherds have also been reported as affected. The mode of inheritance is unknown.


Treating infection or underlying disease is paramount in non-idiopathic forms of the disease. In idiopathic forms, most pets are treated with immunosuppressive drugs, such as steroids, but Vitamin E may also be helpful. With single lesions, surgical excision is considered acceptable.


Because the exact cause of most cases of sterile nodular panniculitis is not known, there are no specific strategies for prevention.

This article has been reviewed by a Veterinarian.

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