Changes

===Clinical Signs===

===Clinical Signs===

In the face of bluetongue virus infection, sheep display characteristic clinical signs¹⁴.  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.

In the face of bluetongue virus infection, sheep display characteristic clinical signs¹⁴.  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.

.  

In peracute cases, severe pulmonary oedema leads to death by asphyxiation around one week after infection. In chronic cases, sheep may die 3-5 wk after infection, mainly as a result of bacterial complications, especially pasteurellosis, and exhaustion. Mild cases usually recover rapidly and completely. The major production losses include deaths, unthriftiness during prolonged convalescence, wool breaks, and possibly reproductive loss. I

The pathogenesis of bluetongue in cattle seems to differ from that in sheep and is based on immediate IgE hypersensitivity reactions. Clinical signs in cattle are rare but may be similar to those seen in sheep. They are usually limited to fever, increased respiratory rate, lacrimation, salivation, stiffness, oral vesicles and ulcers, hyperesthesia, and a vesicular and ulcerative dermatitis. Susceptible cattle and sheep infected during pregnancy may abort or deliver malformed calves or lambs. The malformations include hydranencephaly or porencephaly, which results in ataxia and blindness at birth. White-tailed deer and pronghorn antelope develop severe hemorrhagic disease leading to sudden death. Pregnant dogs abort or give birth to stillborn pups and then die in 3-7 days.

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.  

 

When cattle or sheep are infected during pregnancy, abortions or foetal malformations can arise. Malformations can include hydranencephaly or porencephaly, which results in ataxia and blindness at birth.

===Laboratory Tests===

===Laboratory Tests===