BACKGROUND Anaphylaxis due to nuts is frequent in humans; to the best of the authors' knowledge, it has not been reported previously in dogs. CASE REPORT A 5-year-old female, intact, Vizsla dog was presented with acute diarrhoea, vomiting, respiratory distress and erythematous wheals. The dog had eaten walnuts, which she had been fed in small amounts for years, hours before the onset of clinical signs. A diagnosis of generalized anaphylaxis was made. Skin testing and Western blotting revealed positive results with walnuts and hazelnuts. CONCLUSIONS AND CLINICAL IMPORTANCE This case report illustrates the need for a thorough food history and for recognition that a dog may experience severe allergic reactions to unusual and regularly fed food items. It also shows that allergen specific tests may help to confirm the diagnosis and help in planning the dog's future dietary regime.