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Also known as: '''''Bovine Viral Diarrhoea — Bovine Virus Diarrhoea (Virus) — [[Bovine Viral Diarrhoea Virus#Mucosal Disease|Mucosal Disease]]

Also known as: '''''Bovine Viral Diarrhoea — Bovine Virus Diarrhoea (Virus) — [[Bovine Viral Diarrhoea Virus#Mucosal Disease|Mucosal Disease]]

==Introduction==

==Introduction==

Bovine viral diarrhoea is a viral disease that affects cattle worldwide. Caused by a [[:Category:Pestiviruses|Pestivirus]], it gives rise to significant economic losses in both dairy and beef cattle through its effects on production and reproduction. Bovine viral diarrhoea virus can lead to a variety of clinical outcomes that range from subclinical infections to the more severe presentations including abortion, infertility, and the fatal mucosal disease. The condition is highly immuno-suppressive and secondary respiratory and enteric complications often occur.

Bovine viral diarrhoea is a viral disease that affects cattle worldwide. Caused by a [[:Category:Pestiviruses|Pestivirus]], it gives rise to significant economic losses in both dairy and beef cattle through its effects on production and reproduction. Bovine viral diarrhoea virus can lead to a variety of clinical outcomes that range from subclinical infections to the more severe presentations including abortion, infertility, and the fatal mucosal disease. The condition is highly immuno-suppressive and secondary respiratory and enteric complications often occur.

When acute BVDV infection occurs during pregnancy, the dam may show any of the clinical manifestations that are seen in non-pregnant animals. BVDV is able to cross the placenta and infect the developing foetus and so there may be additional outcomes of infection that depend on the stage of gestation. If infection becomes established at the time of insemination, conception rates may be reduced, and early embryonic death is increased when the virus is introduced at a slightly later stage<ref name="foone">Carlsson, U et al (1989) '''Bovine virus diarrhoea virus: A cause of early pregnancy failure in the cow.''' ''Journal of Veterinary Medicine'', 36, 15-23.</ref><ref name="fotwo">Mc Gowan, M R et al (1993) '''Increased reproductive losses in cattle infected with bovine pestivirus aroung the time of insemination'''  ''Veterinary Record'', 133, 39-43.</ref>.  '''Foetal infection in the first trimester (50-100 days)''' may also result in '''death''', although expulsion of the foetus often does not occur until several months later. An additional effect of foetal infection before 120 days gestation is the birth of '''persistently infected (PI) calves'''.

When acute BVDV infection occurs during pregnancy, the dam may show any of the clinical manifestations that are seen in non-pregnant animals. BVDV is able to cross the placenta and infect the developing foetus and so there may be additional outcomes of infection that depend on the stage of gestation. If infection becomes established at the time of insemination, conception rates may be reduced, and early embryonic death is increased when the virus is introduced at a slightly later stage<ref name="foone">Carlsson, U et al (1989) '''Bovine virus diarrhoea virus: A cause of early pregnancy failure in the cow.''' ''Journal of Veterinary Medicine'', 36, 15-23.</ref><ref name="fotwo">Mc Gowan, M R et al (1993) '''Increased reproductive losses in cattle infected with bovine pestivirus aroung the time of insemination'''  ''Veterinary Record'', 133, 39-43.</ref>.  '''Foetal infection in the first trimester (50-100 days)''' may also result in '''death''', although expulsion of the foetus often does not occur until several months later. An additional effect of foetal infection before 120 days gestation is the birth of '''persistently infected (PI) calves'''.

'''Congenital defects''' can arise from transplacental infection '''between days 100 and 150'''. This is caused by an inappropriate inflammatory response mounted to BVDV by the immune system, which is undergoing the final phase of development at this stage<ref name="thfive"/>. Examples of common congenital abnormalities include defects of the thymus, ocular changes and cerebellar hypoplasia<ref name="thone"/>. Calves with cerebellar hypoplasia ataxic, reluctant to stand and may suffer tremors<ref name="thsix"/>, and ocular pathology often causes blindness and cataracts. Localisation of virus to the vascular endothelium gives vasculitis, leading to oedema, hypoxia and cellular degeneration. Weak, stunted calves may also be produced by BVDV infection in the second trimester.

'''Congenital defects''' can arise from transplacental infection '''between days 100 and 150'''. This is caused by an inappropriate inflammatory response mounted to BVDV by the immune system, which is undergoing the final phase of development at this stage<ref name="thfive"/>. Examples of common congenital abnormalities include defects of the thymus, ocular changes and cerebellar hypoplasia<ref name="thone"/>. Calves with cerebellar hypoplasia are ataxic, reluctant to stand and may suffer tremors<ref name="thsix"/>, and ocular pathology often causes blindness and cataracts. Localisation of virus to the vascular endothelium gives vasculitis, leading to oedema, hypoxia and cellular degeneration. Weak, stunted calves may also be produced by BVDV infection in the second trimester.

Infection in the '''third trimester trimester (over 180-200 days)''' elicits a response from the fully-developed immune system, giving rise to '''normal but seropositive calves'''.

Infection in the '''third trimester trimester (over 180-200 days)''' elicits a response from the fully-developed immune system, giving rise to '''normal but seropositive calves'''.

====Mucosal Disease====

====Mucosal Disease====

[[Image:Mucosal disease cartoon.jpg|right|thumb|150px|Cartoon depicting the development of mucosal disease (Courtesy Prof Joe Brownlie, RVC)]]

[[Image:Mucosal disease cartoon.jpg|right|thumb|200px|Cartoon depicting the development of mucosal disease (Courtesy Prof Joe Brownlie, RVC)]]

Mucosal disease is an invariably fatal condition of 6-18 month-old cattle<ref name="fofive">Brownlie, J (1990) '''Pathogenesis of mucosal disease and molecular aspects of bovine virus diarrhoea virus''' ''Veterinary Microbiology'', 23, 371-382.</ref>. Disease follows a course of several days to weeks and intially presents as pyrexia, depression and weakness. Anorexia leads to emaciation, and animals suffer watery, foul-smelling and sometimes bloody diarrhoea. Dehydration ensues. As suggested by the name, lesions are localised to mucosal surfaces. These include the oral mucosa, tongue, external nares, nasal cavities and conjunctiva<ref name="thone"/>, where large lesions  cause excessive salivation, lacrimation, and oculo-nasal discharge. The coronet and interdigital surface are also affected, causing the animal to become disinclined to walk and eventually recumbent.

Mucosal disease is an invariably fatal condition of 6-18 month-old cattle<ref name="fofive">Brownlie, J (1990) '''Pathogenesis of mucosal disease and molecular aspects of bovine virus diarrhoea virus''' ''Veterinary Microbiology'', 23, 371-382.</ref>. Disease follows a course of several days to weeks and intially presents as pyrexia, depression and weakness. Anorexia leads to emaciation, and animals suffer watery, foul-smelling and sometimes bloody diarrhoea. Dehydration ensues. As suggested by the name, lesions are localised to mucosal surfaces. These include the oral mucosa, tongue, external nares, nasal cavities and conjunctiva<ref name="thone"/>, where large lesions  cause excessive salivation, lacrimation, and oculo-nasal discharge. The coronet and interdigital surface are also affected, causing the animal to become disinclined to walk and eventually recumbent.

===Pathology===

===Pathology===

In cases of mild, acute BVD, lesions are rarely seen. When disease is more severe, the lymph nodes may appear swollen, there may be erosions and ulcerations of the gastrointestinal tract tract and serosal surfaces of the viscera may show petechial and ecchymotic hemorrhages<ref name="forty"/>.

In cases of mild, acute BVD, lesions are rarely seen. When disease is more severe, the lymph nodes may appear swollen, there may be erosions and ulcerations of the gastrointestinal tract tract and serosal surfaces of the viscera may show petechial and ecchymotic hemorrhages<ref name="forty"/>.

The pathology associated with mucosal disease is much more striking<ref name="thone"/>. Oral, lingual and buccal erosions are observed, and buccal lesions often coalesce to form larger areas of necrosis and sloughed epithelium. Oesophageal lesions present similarly. The gastrointestinal tract often shows characteristic pathology, but post-mortem examination must be performed soon after death so that these are not masked by autolytic changes. In the rumen, ulceration is less common but, with congestion and oedema, may be seen along the pillars, and papillae can be reduced in size. Several discoid erosions of around 5mm in diameter appear in the abomasum, with hyperaemia of the surrounding mucosa and petechiation of the submucosa, particularly at the pylorus. Abomasal erosions occasionally enlarge and ulcerate. Oval erosions can be seen along the antimesenteric surface of the small intestine, overlying the lymphatic tissue of the Peyer's patches and measuring 2-5 centimetres in length. The erosions become larger and more numerous towards the terminal ileum, and the exposed surfaces varies in appearance. In more chronic lesions, food is seen to adhere to the underlying submucosa, and in acute disease the exposed surface is acutely congested and often haemorrhages into the gut lumen. In the large intestine, the mucosal folds may be thickened, giving the organ a striped appearance inwardly. Petechiation and erosions are occasionally seen along the folds, and the large intestinal contents are watery, dark and foul-smelling.

The pathology associated with mucosal disease is much more striking<ref name="thone"/>. Oral, lingual and buccal erosions are observed, and buccal lesions often coalesce to form larger areas of necrosis and sloughed epithelium. Oesophageal lesions present similarly. The gastrointestinal tract often shows characteristic pathology, but post-mortem examination must be performed soon after death so that these are not masked by autolytic changes. In the rumen, ulceration is less common but, with congestion and oedema, may be seen along the pillars, and papillae can be reduced in size. Several discoid erosions of around 5mm in diameter appear in the abomasum, with hyperaemia of the surrounding mucosa and petechiation of the submucosa, particularly at the pylorus. Abomasal erosions occasionally enlarge and ulcerate. Oval erosions can be seen along the antimesenteric surface of the small intestine, overlying the lymphatic tissue of the Peyer's patches and measuring 2-5 centimetres in length. The erosions become larger and more numerous towards the terminal ileum, and the exposed surfaces varies in appearance. In more chronic lesions, food is seen to adhere to the underlying submucosa, and in acute disease the exposed surface is acutely congested and often haemorrhages into the gut lumen. In the large intestine, the mucosal folds may be thickened, giving the organ a striped appearance inwardly. Petechiation and erosions are occasionally seen along the folds, and the large intestinal contents are watery, dark and foul-smelling.

==Treatment and Control==

==Treatment and Control==

{{Joe Brownlie

{{Joe Brownlie

|date = July 8, 2011}}

|date = July 8, 2011}}

[[Category:Pestiviruses]][[Category:Cattle Viruses]][[Category:Alimentary Diseases - Cattle]][[Category:Reproductive Diseases - Cattle]]

[[Category:Pestiviruses]][[Category:Cattle Viruses]][[Category:Alimentary Diseases - Cattle]][[Category:Reproductive Diseases - Cattle]]

[[Category:Oral_Cavity_-_Erosive_&_Ulcerative_Pathology]]

[[Category:Oral_Cavity_-_Erosive_&_Ulcerative_Pathology]]

[[Category:Enteritis,_Ulcerative]][[Category:Enteritis,_Viral]] [[Category:Joe Brownlie reviewed]]

[[Category:Enteritis,_Ulcerative]][[Category:Enteritis,_Viral]] [[Category:Joe Brownlie reviewed]]