Systematic Veterinary Virology

MUCOSAL DISEASE

• Acute and chronic mucosal disease are highly fatal forms of BVD seen in persistently infected cattle. These diseases occur when persistently infected cattle become superinfected with cytopathic BVDV.
• The origin of the cytopathic BVDV is usually internal, resulting from mutation of the persistent noncytopathic BVDV.
• Clinical signs of chronic mucosal disease may last several weeks to months. This form is characterized by fever, depression, anorexia and excessive salivation followed by profuse, watery diarrhoea 2-4 days later.
• Affected animals have erosive lesions in their mouths, mainly on the front of the hard palate, the corners of the mouth and the dental pad (gums).
• Other signs include a mucopurulent discharge from the nostrils, tearing of the eyes, corneal edema and lameness.
• Affected animals have a low white blood cell count, up to 50% below normal. Affected animals progressively become weaker and dehydrated and die in 5-7 days.
• Some animals do not die after developing mucosal disease but become chronically ill.
• They become progressively more emaciated with bouts of diarrhoea and bloat. Hoof deformities and erosive lesions on the skin that do not heal.