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