Canine sterile neutrophilic dermatosis (resembling Sweet's syndrome) with severe extracutaneous manifestations

Sterile neutrophilic dermatosis is a rare disease in dogs, similar to Sweet's syndrome in humans. This case report describes the treatment of a 2-year old Bearded Collie that was presented with a 3-week history of fever, hind-limb weakness, peripheral lymphadenomegaly and leucocytosis. Blood tests revealed severe leukocytosis, renal azotaemia, elevated liver enzymes and bilirubinaemia. Skin lesions started to appear in week four. Histology revealed a sterile neutrophilic dermatitis resembling Sweet's syndrome. The dog displayed extracutaneous manifestations, including fever, polyarthritis, a severe leukemoid reaction, anaemia, hepatopathy and nephropathy. Issues regarding the use of criteria for the diagnosis of Sweet's syndrome in humans that are used for dogs with sterile neutrophilic dermatosis, are discussed in this case report. The condition resolved with dexamethasone and mycophenolate mofetil as a novel steroid-sparing therapy. Three months later the dog relapsed, which rapidly responded to short-term dexamethasone treatment and temporarily increased mycophenolate mofetil dosage.