Injection Site Reaction

• May be caused by subcutaneous injections
• Granulomatous nodules form with central necrotic and foreign material
• Macrophages and multinucleated giant cells around the centre
• Surrounded by granulation tissue, perivascular lymphocytes that may form lymphoid follicles, eosinophils
• Cats may develop fibrosarcomas secondary to vaccination
• Dogs, especially poodles, may develop lymphoplasmacytic panniculitis and perivasculitis, vasculitis and follicular atrophy secondary to killed rabies vaccine