Blue tongue
Synonym: Catarrhal fever of sheep, Sore muzzle of sheep
Definition
Aetiology
Incidence
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The disease was first recognized in South Africa in 1902.
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It is now reported worldwide in tropical, subtropical and temperate climates.
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Blue tongue is endemic in India.
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The recent incidence of blue tongue in sheep, cattle and buffaloes has increased mani fold in our country
Susceptibility
Transmission
Pathogenesis
Affecting the blood vessels – Hyperemia, oedema & Haemorrhage.
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Virus entry into host
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Initial replication in haematopoietic cells
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Viremia
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Subsquent replication in endothelial cells
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Swelling in endothelial cells ( Degeneration and necrosis)
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Oedema,haemorrhage
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Thrombosis and infarction
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Affecting haemopoietic tissue – Anaemia and leucopenia results
Clinical signs
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High fever with reddening of nasal and oral mucosa
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Dyspnoea and salivation
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Watery discharge from the nostrils , mucous dry and form crusts
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Tongue appears bluish or cyanotic and swollen
Gross lesions
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Oedema of lips, nose, ear and inter mandibular space "Oedema and cyanosis of Tongue "– ‘Blue Tongue’
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Later petechiae appears on the oral and nasal mucosa
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Gangrene occurs
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When fever subsides- flushing of feet- warm and reddened
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CORONET - haemorrhage at the junction of skin and hoof -Lameness
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Epithelium of hooves shed leaving excoriation and bleeding points
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Fever (Subsides) - pain occurs around the coronary band of feet - lameness
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Spread through Respiratory and Digestive tract – Pneumonia along with gastroenteritis occurs -emaciation – prostration – muscular weakness.
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Haemorrhages may be found on the mucosa of abomasum and intestine as well as in the myocardium
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Serosanguineous fluid in the pericardial sac
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Liver -Fatty change
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Spleen- congestion and swelling
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Death may be due to Pneumonia because of secondary bacterial infection
Pathognomonic Lesions – Haemorrhages at the base of the pulmonary artery and aorta
Microscopic lesions
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Loss of striationa & hyalinization of musculature
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Haemorrhages , oedema and necrosis are seen in affected organs
Diagnosis
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Symptoms - Blue tongue and coronet haemorrhages
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Gross lesion -Haemorrhages at the base of the pulmonary artery and aorta
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Egg inoculation and inoculation into lambs for virus isolation and characterization
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Virus neutralization test
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Last modified: Saturday, 3 December 2011, 5:36 AM