EVOLUTION

ANIMAL BREEDS

DISEASES

MEDICATIONS

FOOD/FEED

BEHAVIOUR

EXOTIC ANIMALS

SPECIAL SECTION

Viral Disease - Bovine Viral Diarrhoea and Mucosal Disease

Definition

BVD is a contagious disease of cattle and characterized by high morbidity but low mortality and severe diarrhea.

Mucosal disease is a disease with very high mortality and severe diarrhea

Etiology

Both diseases are caused by antigenically related pestiviruses

Two biotypes are seen Cytopathogenic &Non cytopathogenic

Incidence

BVD - first reported in New York state 1946

Mucosal disease in Canada 1946

Also reported in India

Transmission

Direct contact between animals

Trans placental to foetus

Nasal secretions, feaces, urine, tears, milk, semen

Aborted fetuses

Persistently infected bulls

Persistently viraemic female animals

Susceptibility

6 months to 2 years old cattle

Clinical Signs

High fever (105˚ - 108˚F)

Anorexia, depression

Diarrhoea

Excessive salivation

Stringy mucus hanging from the muzzle to the ground

Leucopenia

Ulcers in mouth, nose, muzzle

Congestion of nasal mucosa and conjunctiva

Ears, muzzle and extremities are cold while other parts of body are warm

Dehydration

Lack of milk secretion & rumination

Abortions, still births, mummified fetuses

Calves born alive are persistently infected

Congenital cerebellar hypoplasia, cataracts, retinal atrophy, micro opthalmia, optic neuritis in calves born alive

Gross Lessons

Ulceration & erosions of mucosa of gastrointestinal tract - dental pad, palate, tongue, inside of cheeks, muzzle and external nares

Pharynx - irregularly shaped ulcers covered by mucus exudate

Esophagus - erosions and ulceration of mucosa

Abomasum - congestion, haemorrhages & ulcers

Omasum - Hemorrhagic

Small intestine, caecum and colon - ulcers and necrosis particularly on Peyer's patches

Necrosis of lymphocytes in Lymphnodes & spleen -

Chronic mucosal disease causes chronic ulceration of oral cavity and skin, and lameness

Diagnosis

Differential diagnosis from Rinderpest and Malignant catarrhal fever

Cross serum neutralization test used to differentiate from Rinderpest

Malignant catarrhal fever spreads slowly with characteristic ocular, nasal & brain lesions

Virus isolation and identification

ELISA test

Treatment

There is no specific treatment for any of the diseases associated with the BVDV.

The prognosis for severe cases of mucosal disease with profuse watery diarrhea and marked oral lesions is unfavorable and slaughter for salvage or euthanasia should be considered.

Animals with chronic BVD should be culled and destroyed.

Control and Prevention

The continued presence of the BVDV in the bovine population is not due to the lack of quality diagnostic tests. BVDV continues to cause significant economic losses because of failures in implementing a sound immunization program, failures in establishing herd-monitoring programs, and failures in developing effective biosecurity and bio containment programs.

A combination of biosecurity, vaccination, and bio containment strategies are necessary to control and prevent BVDV infection and its consequences in a herd and country.

Biosecurity is the action taken to prevent the introduction of a disease agent into a herd or region.

The goal of a BVDV biosecurity program is to prevent the introduction of the virus into the cattle herd and preventing transmission of the virus to susceptible animals.

Bio containment includes the strategies to control an already existing disease in a herd or region.

The goal of bio containment is to minimize the occurrence or severity of disease associated with BVDV infection, or to completely eliminates the virus from the herd.

Bio containment includes actions to increase host immunity.

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