The aetiology is uncertain but assumed to be secondary to '''haematogenous spread''' or penetrating '''foreign bodies'''. '''Anaerobic''' culture is frequently required to produce any growth from samples. [[Pasteurella and Mannheimia species - Overview|''Pasteurella'']] has been grown from dogs with orbital cellulitis, whilst [[Aspergillus spp.|''Aspergillus'']] and ''Penicillium'' has been grown from cats. | The aetiology is uncertain but assumed to be secondary to '''haematogenous spread''' or penetrating '''foreign bodies'''. '''Anaerobic''' culture is frequently required to produce any growth from samples. [[Pasteurella and Mannheimia species - Overview|''Pasteurella'']] has been grown from dogs with orbital cellulitis, whilst [[Aspergillus spp.|''Aspergillus'']] and ''Penicillium'' has been grown from cats. |