A one-year-old, intact female, Yorkshire terrier dog was presented with a six-month history of multi-focal, polycyclic erythematous lesions with epidermal collarette formation at the axillae, the trunk and ventral abdomen. The dog had a history of an inappropriate vaccine administration one day prior to the onset of clinical signs. The histopathology of the lesions revealed apoptosis of keratinocytes in the overlying epidermis, hydropic degeneration and lymphocytic exocytosis. The clinical signs and histopathology of the lesions were compatible with erythema multiforme. The skin lesions resolved after treatment with prednisolone combined with azathio-prine for one month. No recurrence of clinical signs occurred during the follow-up period (four months). This is the first case report of erythema multiforme associated with an accidental subcutaneous injection of a Bordetella bronchiseptica vaccine.