Putative cutaneous adverse drug reactions in two dogs

We describe two cases of cutaneous adverse drug reactions (CADR) in dogs. Case 1 presented with erythematous macules with sharply demarcated margins on the abdomen and inguinal area and depigmentation on the lip. Skin lesions appeared after 3 weeks of administration of anti-epileptic drugs, including phenobarbital. All medications were discontinued, and the skin lesions gradually resolved 4 weeks after discontinuation. Case 2 presented with an erythematous macule-to-plaque and erosion on the abdomen and inguinal area after treatment with multiple antibiotics (metronidazole, cefotaxime and marbofloxacin) for 5 days. Histopathological findings revealed large numbers of neutrophils marginating along the endothelium and accumulating around blood vessels. Therefore, the dog was diagnosed with drug-induced vasculitis, and previously prescribed drugs were discontinued. Two weeks after discontinuation of previously prescribed drugs, no active skin lesions were observed. CADR can be accompanied by a variety of onset times and clinical manifestations, and suspected drugs should be discontinued when CADR is suspected.