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| − | [[Liver, Herpes Virus Infections]]
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| − | ====[[Feline Infectious Peritonitis]]====
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| − | ===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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| − |
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| − | ====Hepatic abscessation====
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| − | *with supportive hepatitis
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| − | *especially common in cattle and sheep
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| − | =====Causes=====
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| − | *bacteria involved
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| − | **''Fusobacterium necrophorum'' 80% +
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| − | **''Arcanobacterium pyogenes''
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| − | **''Streptococcus''
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| − | **''Staphylococcus''
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| − | **''Bacteroides''
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| − | *spread from umbilicus in young animals
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| − | **omphalophlebitis (navel ill)
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| − | **usually mixed bacteria
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| − | ***''Actinomyces pyogenes''
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| − | ***''Staphylococci'' (predominates)
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| − | *haematogenously from other pyaemic source
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| − | **eg metritis or mastitis
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| − | **bacteria invade ruminal wall and enter portal circulation to [[Liver - Anatomy & Physiology|liver]]
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| − | *from rumenitis caused by overfeeding with grain
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| − | **erosion of ruminal epithelium due to acidosis
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| − |
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| − | =====Clinical Signs=====
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| − | *subclinical
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| − | *detected at exploratory laparotomy or sluaghter
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| − | *weight loss (most important)
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| − | *decreased weight gain or milk yields
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| − | *sporadic fever and anorexia
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| − | NB: animals can appear in good health as long as abscesses do not rupture
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| − | =====Gross=====
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| − | *large
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| − | *pale greenish-yellow pus
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| − | *thick fibrous capsule
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| − | =====Sequelae=====
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| − | *variable
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| − | **resorption and healing
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| − | **abscess may extend into the heaptic vein
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| − | ***give rise to thrombosis in the caudal vena cava
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| − | ***possible pulmonary abscesses
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| − | ***endocarditis
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| − | **fibrous adhesion to adjacent viscera
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| − | ***if the abscess is near the surface
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| − | **epistaxis, sudden death
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| − | NB: in many cases, abscesses are incidental findings at slaughter and result in condemnation of the affected [[Liver - Anatomy & Physiology|livers]]
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| − |
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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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| − |
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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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| − |
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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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| − |
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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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| − |
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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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| − |
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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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| − |
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| − | =====''Nocardia species''=====
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| − | *dogs
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| − | *cause pyogranulomatous foci
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| | ===Parasitic=== | | ===Parasitic=== |