Differential diagnosis of diseases causing oral lesions in cattle.
The differential diagnosis of diseases causing oral lesions in cattle can pose problems both clinically and at necropsy. Several diseases can be associated with crusting of the muzzle, and erosion, ulceration, necrosis and, occasionally, vesiculation of the oral mucosa. Few signs or lesions associated with oral infection are pathognomonic and an aetiological diagnosis based solely on clinical observation is often not possible. An accurate diagnosis is essential so that any potentially devastating disease is recognised at an early stage. In the UK, the most crucial diagnostic differentiation is foot-and-mouth disease, the clinical signs and lesions of which may initially be confused with a number of other viral diseases, including vesicular stomatitis, bovine papular stomatitis, bovine virus diarrhoea/mucosaL disease, malignant catarrhal fever, rinderpest and bluetongue. Competent regulatory authorities must therefore be involved where any diagnostic doubt exists. In such cases, a specific diagnosis must be based on laboratory tests, including virus isolation and serology. This article discusses the differential diagnosis of these conditions, with particular emphasis on the recognition of exotic viral diseases. In addition, it reviews some other infectious and non-infectious causes of oral lesions, such as infectious bovine rhinotracheitis, which may give rise to diagnostic uncertainty.