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Cavity & Gingiva - Pathology (view source)

Revision as of 19:23, 29 October 2008

2,340 bytes removed ,  19:23, 29 October 2008
→‎[[Flaviviridae#Bovine Viral Diarrhoea Virus|Bovine Viral Diarrhoea / Mucosal disease]]
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==Erosive & Ulcerative Pathology==
 
==Erosive & Ulcerative Pathology==
 
*"True ulcer" occurs when connective tissue under epithelium is exposed i.e. stratum germinativum is breached and then lesion takes much longer to heal.
 
*"True ulcer" occurs when connective tissue under epithelium is exposed i.e. stratum germinativum is breached and then lesion takes much longer to heal.
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===[[Flaviviridae#Bovine Viral Diarrhoea Virus|Bovine Viral Diarrhoea / Mucosal disease]]===
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===[[Bovine Virus Diarrhoea Virus]]===
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[[Image:BVD-MD.gif|right|thumb|125px|<small><center>Small erosions of MDV/BVDV - vesicles are microscopic (Courtesy of Alun Williams (RVC))</center></small>]]
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*'''Mucosal Disease''': erosive condition produces small multiple, cleanly punched out lesion in mouth
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[[Image:Bvd2.gif|right|thumb|125px|<small><center>Coalescing lesions of BVDV (Courtesy of Alun Williams (RVC))</center></small>]]
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*Erosive condition produces small multiple, cleanly punched out lesion in mouth.
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*A major concern is that it can be confused with FMD (especially as it often occurs with clinical signs of salivation and depression).
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*Two manifestations of disease with different severity, given different names but same condition and causal agent.
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#Mucosal Disease (MD)
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#Bovine Virus Diarrhoea (BVD).
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====Pathogenesis====
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*Caused by number of strains of [[Flaviviridae#Pestiviruses|Pestiviruses]] that are all closely related but produce two distinct syndromes.
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*Two biotypes of virus cytopathic and non-cytopathic.
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=====1. Bovine Viral Diarrhoea=====
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*Often may sweep through a whole colony of young stock causing profuse diarrhoea (perhaps febrile) for a few days and then recover.
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*Due to primary exposure to cytopathic strain of virus.
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=====2. Mucosal Disease=====
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*Presents as severe disease with lesions in mouth, profuse watery diarrhoea and '''always eventually results in death'''.
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*It is the end result of an animal becoming infected in utero with non-cytopathic strain of virus. (cow may not show any signs). 
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*The foetus is tolerant of the virus and becomes persistently infected (if infected before 2nd month gestation).
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*It is believed that later mutational events in the persistent non-cytopathic virus or subsequent infection with a cytopathic strain lead to establishment of a pathogenic infection. The animal thus develops severe disease and dies as it makes no immune response to cytopathic virus. It is found to be infected by two closely related strains of virus, one cytopathic and the other non-cytopathic.
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*A dam infected by a cytopathic strain may produce a deformed foetus.
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*[[Cerebellar hypoplasia]], [[micro-opthalmia]] and other ocular abnormalities are common abnormalities.
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====Pathology====
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*Erosive lesions '''size of 5p''' piece develop in mouth, almost circular not ragged.  Multiple.  May coalesce and look more like FMD. 
   
*Neutrophils invade the ulcer and if bacterial colonisation occurs, further excavation follows. Either:
 
*Neutrophils invade the ulcer and if bacterial colonisation occurs, further excavation follows. Either:
 
::#This lesion develops a granular base and becomes diphtheritic.  
 
::#This lesion develops a granular base and becomes diphtheritic.  
 
::#If bacterial colonisation does not take place, healing occurs within fourteen days.  
 
::#If bacterial colonisation does not take place, healing occurs within fourteen days.  
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*Seen in most parts of mouth (or maybe on muzzle) e.g. dental pad, [[Cheeks - Anatomy & Physiology|cheeks]], sides of [[Oral Cavity - Tongue - Anatomy & Physiology|tongue]].
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*Seen in most parts of mouth (or maybe on muzzle) e.g. dental pad, [[Cheeks - Anatomy & Physiology|cheeks]], sides of [[Oral Cavity - Tongue - Anatomy & Physiology|tongue]]
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*Lesions extend throughout gut with particularly big ulcers in small intestine over [[Peyer's Patches - Anatomy & Physiology|Peyers patches]]. Necrosis occurs in lymph nodes and [[Spleen - Anatomy & Physiology|spleen]].
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*Lesions extend throughout gut with particularly big ulcers in small intestine over [[Peyer's Patches - Anatomy & Physiology|Peyers patches]]. Necrosis occurs in lymph nodes and [[Spleen - Anatomy & Physiology|spleen]]
    
====<span id="BVDHistology">Histology</span>====
 
====<span id="BVDHistology">Histology</span>====
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*No vesicular stage, [[prickle cell]]s die off from surface resulting in layer of necrotic debris over epithelial layer.
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*No vesicular stage, prickle cells die off from surface resulting in layer of necrotic debris over epithelial layer
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*Infection penetrates inward through stratum germinativum.
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*Infection penetrates inward through stratum germinativum.
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*Epithelium does not recover as animal does not recover.
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*Epithelium does not recover as animal does not recover
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====Definitive diagnosis====
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*Viral antigen in blood 3-8 days post infection
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**(N.B Tolerant state exists when considering serology.)
      
===[[Malignant Catarrhal Fever]]===
 
===[[Malignant Catarrhal Fever]]===
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