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Category:Hepatitis, Bacterial (view source)

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|pagetitle =Hepatitis, Bacterial
 
|pagetitle =Hepatitis, Bacterial
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*bacteria can enter the [[Liver - Anatomy & Physiology|liver]] through a variety of routes
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**direct implantation
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***eg foreign body penetration from [[The Reticulum - Anatomy & Physiology|reticulum]]
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**direct extension from disease in adjacent tissues of supportive [[Peritoneal Cavity Inflammatory - Pathology|peritonitis]]
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**haematogenously
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***via the umbilical vein from an infected umbilicus
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***via the portal vein in the [[Alimentary - Anatomy & Physiology|alimentary tract]]
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***via the hepatic artery in bacteraemias and septicaemias
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***via the bile ducts
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*the [[Liver - Anatomy & Physiology|liver]] may show microscopic evidence of involvement in a large variety of systemic infections
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*these can be accompanied by jaundice
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*the changes in the [[Liver - Anatomy & Physiology|liver]] are diffuse with many small areas of necrosis surrounded by [[Neutrophils - WikiBlood|neutrophils]] and [[Lymphocytes - WikiBlood|lymphocytes]]
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**eg Salmonellosis or Listeriosis
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====[[Hepatic Abscessation]]====
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====Bacillary necrosis====
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*''Fusobacterium necrophorum''
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*calves and lambs
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*common in intensively reared beef cattle
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*occurs following an infected umbilicus in neonates and from rumenitis in adult cattle
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=====Gross=====
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*rounded pale multiple foci of coagulative necrosis throughout the [[Liver - Anatomy & Physiology|liver]]
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*unsoftened, greyish-yellow patches
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*ringed by a zone of hyperaemia
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*foci coalesce in severe cases
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*in adult animals, these lesions may have progressed to abscesses following lysis of the coagulated necrotic tissue and the formation of fibrous capsule around the damaged tissue
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*if animal survives, these lesions may soften develop into abscesses
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=====Microscopically=====
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*coagulative necrosis
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*possible evidence of migrating flukes
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*bacteria can be demonstrated in the periphery of the necrotic tissue, especially near its junction with viable tissue
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*there is a rim of neutrophilic cells
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====Infectious Necrotic Hepatitis (Black Disease)====
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*''Clostridium novyi'' type B
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*grazing animals
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**mainly sheep, also cattle (and reported sometimes in horses and goats)
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*organism is widely distributed within the soil and normally present in GIT and [[Liver - Anatomy & Physiology|liver]] of grazing animals on infected pastures
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**worldwide
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*it is ingested by the animal and spores are absorbed via the gut and travel to the [[Liver - Anatomy & Physiology|liver]] , where they lie dormant in [[Macrophages - WikiBlood|macrophages (Kupffer cells)]] - also found in [[Bone Marrow - Anatomy & Physiology|bone marrow]] and [[Spleen - Anatomy & Physiology|spleen]]
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*seasonal disease associated with Fasciola [[Liver - Anatomy & Physiology|liver]] flukes
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**migrating immature [[Liver - Anatomy & Physiology|liver]] flukes precipitate the disease
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**causes [[Liver - Anatomy & Physiology|liver]] damage which provides ideal anaerobic conditions for the activation and germination of spores
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*''C. novyi'' produces three exotoxins
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**alpha - a lethal toxin
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**beta - a lecithinase which is both haemolytic and necrotising
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**zeta - a haemolytic toxin
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*acute toxaemia produced by organism
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**affected animals are usually found dead because death is sudden due to the action of the powerful bacterial endotoxins
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**not all animals will become sick - only when organism starts producing toxin
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*post mortem changes occur rapidly
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=====Clinical=====
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*found dead/sudden death
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**well conditioned sheep 2-4 years old
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**lateral recumbency, few signs of struggle
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**vaccination history (against Clostridium)
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**no red urine or other bleeding
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*IF seen alive
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**severe depression
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**not eating
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**pyrexia
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**hypothermia
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**respiratory distress
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**muffled heart sounds
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=====Gross=====
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*rapid decomposition of carcass
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*extensive subcutaneous vessels engorged and haemorrhage causing dark colouration of the skin - hence the name ''''Black Disease'''' - and oedema
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*blood stained fibrinous fluid in abdomen, thorax, and pericardium which clots on exposure to air
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*tissues are autolysed
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*[[Liver - Anatomy & Physiology|liver]] swollen and congested
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*characteristic pale (greyish-yellow) foci (3cm diameter) of necrosis surrounded by a rim of haemorrhage where the bacteria have multiplied upon incision
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*evidence of [[Liver - Anatomy & Physiology|liver]] fluke
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*other organs show general signs of toxaemia
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NB: Distinguish Black Disease from Red Water!  The former will have several small areas of necrosis while the latter has one big lump
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=====Microscopically=====
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*coagulative necrosis
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*possible evidence of migrating flukes
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*demonstration of bacteria
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**in the necrotic tissue
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**especially near its junction with viable tissue
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**rim of neutrophilic cells
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=====Treatment=====
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*rarely possible
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*Penicillin or Oxytetracycline at very high doses
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=====Prevention=====
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*vaccination
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**normally lasts up to 6 months
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*[[Liver - Anatomy & Physiology|liver]] fluke control
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*remove dead carcasses from pasture
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====Bacillary Haemoglobinuria (Red Water)====
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*''Clostridium haemolyticum'' AKA ''Clostridium novyi'' Type D
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*cattle and sheep
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*highly fatal
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*similar pathogenesis to ''C. novyi''
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*beta toxin produced
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**causes hepatic necrosis and intravascular haemolysis
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*C. haemolyticum found in soil, poorly drained/wet pastures
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*spores found routinely in [[Liver - Anatomy & Physiology|liver]] and GIT and faeces of grazing animals in affected pastures
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*need disease in [[Liver - Anatomy & Physiology|liver]] casing anaerobic conditions to allow bacterial growth and toxin production
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*normally associated with [[Liver - Anatomy & Physiology|Liver]] Fluke damage
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*disease occurs in some areas and some farms - distribution is poorly understood
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=====Clinical Signs=====
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*found dead/sudden death
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**lateral recumbency
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**bloat
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**little signs of struggle
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**blood in nostrils, mouth, [[Rectum - Anatomy & Physiology|rectum]], [[Female Reprodcutive Tract -The Vagina/Vestibule - Anatomy & Physiology|vagina]]
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*IF seen alive
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**depressed, reluctant to move, pyrexia, respiratory distress
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**red urine (haemoglobinuria) but not consistent
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**pale mucous membranes/jaundice
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**bloody froth in nostrils
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=====Gross=====
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*post mortem is confirmatory finding
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*rapid decomposition of carcass
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**organs decomposed
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*subcutaneous hameorrhages, odema, emphysema
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*blood stained abdominal and thoracic fluid, large quantity and pericardium
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*animal is severely anaemic
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*may be jaundiced
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*red urine in [[Urinary Bladder - Anatomy & Physiology|bladder]], therefore haemoglobin in urine
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*[[Urinary System - Anatomy & Physiology#Upper Urinary System|kidneys]] speckled with haemoglobin
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*blood in lungs/trachea
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*ischaemic hepatic infarct
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**usually a single large necrotic focus in the [[Liver - Anatomy & Physiology|liver]]
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**area of necrosis, sometimes partially liquefied centre, irregular outline with a hyperaemic edge
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=====Microscopically=====
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*presence of Clostridia post mortem must be interpreted with great caution as they are common post mortem invaders
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*FAT for organism
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*identification of toxins
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**need this for diagnosis
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=====Treatment=====
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*unlikely
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*very high doses of penicillin or oxytetracycline
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*blood transfusion
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=====Prevention=====
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*vaccination lasts up to 6 months
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*[[Liver - Anatomy & Physiology|liver]] fluke control
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*remove infected carcasses from pasture
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NB: Distinguish Red Water from Black Disease!  The former will have bleeding out of any orifice while the latter does not
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====Tyzzer's disease====
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*''Bacillus piliformis''
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*affects
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**mostly laboratory rodents
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**possibly foals 1-4 weeks of age
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**young immune-compromised pups and kittens
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*initial intestinal lesions can be hard to find at post mortem examination
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[image from smythes' ppt] wheat sheaf
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====Leptospirosis====
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*''Leptospirosis icterohaemorrhagica'' - a septicaemic disease which affects the [[Liver - Anatomy & Physiology|liver]]
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*puppies
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*Leptospirosis is an important spirochaetal group of diseases causing disease in animals and humans (zoonotic)
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*Transmission
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**via urine of affected animals
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**organisms can remain viable for weeks in damp conditions
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*method of action
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**cause anaemia via intravascular haemolysis
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=====Clinical=====
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*fever
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*dehydration
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*haemorrhaging from the mucous membranes of the body
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=====Diagnosis=====
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*dark field microscopy on fresh urine is best
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=====Gross=====
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*widespread hameorrhages
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*icterus
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*pale foci in the [[Liver - Anatomy & Physiology|liver]] (not always a constant finding)
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*subcapsular and cortical renal haemorrhages
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=====Microscopically=====
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*foci of necrosis
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*dissociation of hepatocytes form each other (similar to post mortem change)
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*substantial haemosiderin in the Kuppfer cells (from the haemolysis)
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*need to use a silver stain or immunofluorescence to demonstrate the organisms in tissues
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====Salmonellosis====
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*''Salmonella dublin''
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*calves
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=====Clinical=====
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*fever
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*dehydration
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*[[Diarrhoea|diarrhoea]]
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=====Gross=====
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*severe, often haemorrhagic, inflammation in the [[Ileum - Anatomy & Physiology|ileum]]
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*'''paratyphoid nodules''' - pale foci of necrosis in the [[Liver - Anatomy & Physiology|liver]]
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=====Microscopically=====
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*foci of hepatocytic necrosis
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*mixed mononuclear inflammatory cell infiltrate
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NB: small foci of hepatocytic necrosis are often found as incidental lesions at post mortem examination
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====Other bacteria causing liver lesions====
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=====''Mycobacterium tuberculosis''=====
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*in all species
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*causes granulomas
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=====''Actinobacillus equuli''=====
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*foals
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*bacteria from the septicaemia localise in the [[Liver - Anatomy & Physiology|liver]] and other tissues, including the [[Urinary System - Anatomy & Physiology#Upper Urinary System|kidney]]
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=====''Nocardia species''=====
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*dogs
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*cause pyogranulomatous foci
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[[Category:Liver_-_Inflammatory_Pathology]]
 
[[Category:Liver_-_Inflammatory_Pathology]]
Bara
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