Changes

===Clinical Signs===

===Clinical Signs===

BT is primarily a disease of sheep but when these animals have positive BTV

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.

serology, care must be taken to avoid confusing clinical BT and diseases with similar

 

The clinical signs in sheep can be very variable, ranging from acute to subclinical.

6.2 The clinical signs in sheep can be very variable, ranging from acute to subclinical.

The acute signs begin with fever, which may last about a week. The

The acute signs begin with fever, which may last about a week. The

incubation period, generally 4–8 days, is possibly influenced by the dose of virus

incubation period, generally 4–8 days, is possibly influenced by the dose of virus

usually no disease is observed.

usually no disease is observed.

Clinical signs occur more rarely in cattle, but when seen are similar to those in sheep. Signs can include pyrexia, tachypnoea, lacrimation, salivation, stiffness, oral vesicles or ulcers, hyperesthesia, and a vesicular, ulcerative dermatitis.  

Clinical signs occur more rarely in cattle, but when seen are similar to those in sheep. Signs can include pyrexia, tachypnoea, lacrimation, salivation, stiffness, oral vesicles or ulcers, hyperesthesia, and a vesicular, ulcerative dermatitis.