A case of atypical multifocal nodular eosinophilic dermatosis in a Labrador retriever dog

Background A dog with gastrointestinal signs and a history of administration of multiple drugs developed acute multifocal to coalescing ulcerative nodules and a large plaque. Objective To describe abnormal nodular clinical lesions with an unexpected superficial and deep severe eosinophilic perivascular to interstitial inflammation. Animal A 7-year-old spayed female Labrador retriever Methods and materials Blood tests, faecal and urinalysis, and abdominal radiographs were performed; skin biopsy samples were taken for cytological, culture and histopathological analyses. Results The blood tests, faecal, urinalysis and radiographs were within normal limits. Cytological results revealed inflammatory cells and cultures had no growth. Histopathological evaluation revealed dermal and subcutaneous oedema, mucin deposition and perivascular to interstitial inflammation predominated by eosinophils with occasional very small intralesional dense aggregates of eosinophils centred on collagen bundles, eosinophilic exocytosis and small eosinophilic pustules. Focal subepidermal fibrin exudation and haemorrhage resulted in epidermal detachment and ulceration. Clinical resolution of the dermatological and gastrointestinal signs was seen with the withdrawal of prior medications and administration of a tapering course of anti-inflammatory doses of prednisolone. Conclusions and clinical importance To the best of the authors' knowledge, this is a novel nodular clinical and eosinophilic histopathological pattern combination. This case offers evidence of a spectrum of sterile eosinophilic dermatoses rather than multiple different disease processes.