Anaphylaxis or Type I hypersensitivity reactions in cattle can result in an atypical interstitial pneumonia. The lung is a major target organ in cattle for Type I hypersensitivity. Clinical signs are those of acute respiratory distress. Cattle that die of anaphylaxis may have lesions consistent with those described for atypical interstitial pneumonia. Treatment is administration of epinephrine; supportive treatment includes anti-inflammatory therapy with corticosteroids or NSAIDs. If pharyngeal or laryngeal edema is present, a tracheostomy may be indicated.