Scabby Mouth

Species

Goats

Sheep

Other Names

Contagious Ecthyma
Orf

Syndromes

Skin Lesions

Description

Scabby mouth is a highly contagious viral disease that affects the skin of sheep and goats. It is caused by the orf virus, a member of the genus Parapoxvirus. Viral challenge is expected to be high during the export process from mixing of young sheep in close confinement. Higher stocking densities and feeding of pellets and hay that may cause small abrasions around the mouth, means the potential for outbreaks of scabby mouth in the export process is considerable.

Assembly facilities can become heavily contaminated as the virus is hardy and can survive in the environment for many years. Unvaccinated animals are susceptible, as are some heavily challenged or immunosuppressed vaccinated animals (although with mild, rapidly healing lesions).

Mainly young animals are affected, as older animals will have recovered from earlier infection. Australian goats appear to be considerably less susceptible than sheep.

The disease is seasonal in Australia’s sheep producing areas, occurring especially in summer and autumn when feed consists of abrasive stubbles, dry grass, seeds and burrs, and when flies are abundant and active. This should be a consideration when assembling sheep and goats for export.

If a significant number of animals have scabby mouth lesions on inspection at the destination, it could lead to rejection of the consignment.

Clinical Signs and Diagnosis

Reddened areas with clear, sticky exudates or hard brown scabs seen on the skin of sheep and goats, especially around the lips and nostrils, is probably scabby mouth. Coalescing of lesions can result in scabs covering a much larger area. As the disease progresses, the scab becomes a dry, cracked crust. Weight loss can be rapid if lips are swollen or the mucosa of the mouth is affected, however, most cases show few systemic clinical signs. Less commonly, lesions can affect other areas of exposed skin such as ears and feet.

Bacteria may infect the cracks and create purulent infections. If the crusts are dislodged, a granular surface is exposed and may show small amounts of pus and blood. Lesions will spontaneously regress over 3-4 weeks, but may persist for longer if there is secondary bacterial infection.

Laboratory confirmation requires scabs with underlying tissue scrapings for virus isolation or identification with electron microscopy.

Treatment

The disease must run its two to three week course as no effective treatment is available. Antibiotics are only warranted if secondary bacterial infection is present. Ready access to soft feed and clean water will encourage eating.

Prevention

There is an effective vaccine that should be administered before expected disease onset or as dictated by importing country protocols.

People handling infected sheep can become infected and should take precautions.