Transmission/cause: Panniculitis is inflammation of the subcutaneous, or fatty layer, of the skin which can result from many different possible causes, including infections (bacterial, fungal, viral), immunologic diseases, trauma, pancreatic disease, vaccination or other drug-induced, or idiopathic (no underlying cause identified).
Affected animals: Panniculitis can occur in both dogs and cats. Although disease can occur in any breed of dog, Dachshunds and Poodles appear to be predisposed to immune-mediated sterile nodular panniculitis.
Clinical signs: There is no age or sex predilection. Panniculitis often appears as deep nodules that can occur singly or affect multiple areas of the body. The nodules can be firm or soft and mobile. The lesions can eventually become cystic and ulcerate, often draining an oily, yellowish-brown to bloody discharge. The lesions are often non-painful. Healing lesions may result in scarring. Severely affected animals may feel ill.
Diagnosis: Definitive diagnosis is made based on biopsy. Aspiration of the mass with microscopic examination may reveal inflammatory cells with numerous lipid droplets and lipocytes (fat cells). Additionally, cultures or blood testing for infectious diseases may be recommended to evaluate for possible underlying infection as a primary cause of the panniculitis. Sterile nodular panniculitis is diagnosed by ruling out all potential infectious causes of disease.
Treatment: Treatment of panniculitis depends on the underlying cause. If an infectious cause is identified, then long term antibiotic or antifungal medication is required. For sterile nodular panniculitis, treatment options include steroids, a combination of doxycycline/niacinamide, or cyclosporin (Atopica). Many animals can enter long-term or permanent remission; others may need to be maintained on medication for life. It may be advised by your veterinarian that vaccination be discontinued or given less frequently as vaccination may trigger a worsening in the disease.
Prognosis: If the underlying disease is corrected, most animals will recover uneventfully. For those where a trigger is not known or corrected, treatment may be needed for life, however, control is usually satisfactory with medical therapy.