Changes

===Clinical Signs===

===Clinical Signs===

Bluetongue is primarily a diseae of sheep, and in the face of infection these animals can display clinical signs ranging from acute to subclinical^{1, 14}. After a 4-6 day incubation period animals develop a pyrexia of 40.5-42°C and become depressed. Facial oedema affects the nose, lips, tongue and submandibular areas. Severe swelling of the tongue results in protrusion and cyanosis, lending the disease its name. The oral mucosa becomes congested, petechiated and ulcerated which leads to inappetance, dysphagia and frothing at the mouth. A serous nasal discharge is later seen to become mucopurulent, and the conjuntiva are often injected. Inflammation of the coronet causes lameness, and the junction of the skin and hoof is purple-red in colour. Skeletal muscle damage in advanced disease may also contribute to lameness. The course of ovine bluetongue can vary from peracute to chronic, and mortality is between 2% and 30%. In peracute cases, severe pulmonary oedema leads to death by asphyxiation around one week after infection. Acute, mild cases normally have a rapid and complete recovery. In chronic cases, death occurs 3-5 weeks after infection due to exhaustion and bacterial complications such as pasteurellosis.

Bluetongue is primarily a disease of sheep, and in the face of infection these animals can display clinical signs ranging from acute to subclinical^{1, 14}. Acute disease follows an incubation period of about one week, which may depend on the infectious dose of virus received.  Signs begin with pyrexia of around 40.5-42°C, and hyperaemia of the oral and nasal mucosa is seen 24-36 hours later accompanied by hypersalivation and a serous nasal discharge. The nasal discharge quickly becomes mucopurulent and potentially blood-tinged, and dries to froms a crust around the nostrils. Facial oedema affects the nose, lips, tongue and submandibular areas. Severe swelling of the tongue results in protrusion and cyanosis, lending the disease its name. The oral mucosa becomes congested, petechiated and ulcerated which leads to inappetance, dysphagia and frothing at the mouth. A serous nasal discharge is later seen to become mucopurulent, and the conjuntiva are often injected. Inflammation of the coronet causes lameness, and the junction of the skin and hoof is purple-red in colour. Skeletal muscle damage in advanced disease may also contribute to lameness. The course of ovine bluetongue can vary from peracute to chronic, and mortality is between 2% and 30%. In peracute cases, severe pulmonary oedema leads to death by asphyxiation around one week after infection. Acute, mild cases normally have a rapid and complete recovery. In chronic cases, death occurs 3-5 weeks after infection due to exhaustion and bacterial complications such as pasteurellosis.

 

 

In acute cases, the lips and tongue become very swollen and oedema may extend over

In acute cases, the lips and tongue become very swollen and oedema may extend over

the face to include the ears and intermandibular space. The hyperaemia becomes more

the face to include the ears and intermandibular space. The hyperaemia becomes more