Difference between revisions of "Category:Enteritis, Fibrinous/Haemorrhagic"

Pathology

• The mucosa eroded to produce lesions of darkish-red submucosa covered in dry, crumbly fibrin.
• Is usually caused by severe damage due to secondary bacterial infection following an earlier milder insult.
• Tends to be more severe in the lower small intestine and upper large intestine.
  • Many severe infections tend to get worse further down the gut.
    • Catarrhal change may be seen in the upper small intestine and fibrinous change in the lower small intestines.
  • In the lower aprt of the bowel, where the inflammation is more severe, disease is more anaerobic.
    • Lesions are caused by anaerobic organisms- convert mild diseases into more serious disease.

Salmonellosis

Swine Dysentery

• Swine dysentery gives rise to fibrinous/ haemorrhagic enteritis.
• A quite common and important disease.
• The disease is caused by Brachyspira hyodysenteriae.
  • Is not seen in gnotobiotic animals - other enteric pathogens such as Fusobacterium or Bacteroides may therefore also be required in order to produce disease.
• The disease is NOT systemic.
  • Localised to the large intestine- in particular, the spiral colon.
• Swine dysentery is spread by the faeco-oral route, and is carried by pigs and rodents.

Clinical

• Affects post weaning pigs at approximately 4 months of age.
• White scour becomes a liquid dirty red / brown scour with a foul smell.
  • Contains poorly digested focal shreds of mucosa and fibrin strands.
    • Mucoid covered faeces.
• There are three outcomes to infection; the animal may:
  • Die
  • There is a morbidity up to 90% in the herd, with up to 50% mortality.
  • Recover
  • Become chronically infected.
• Symptoms are due to loss of absorption in colon.
  • The colon is normally a key site of absorption for water and electrolytes in the pig.

Pathology

• The serosa of the spiral colon may appear shiny from the outside.
  • Is turgid and oedematous.
  • In severe cases, haemorrhage may be seen.
• The small intestine NOT affected.
• Fibrinous deposits are seen on the mucosa as the disease progresses.
  • The mucosa underneath is eroded to expose blood vessels in lamina propria.
    • Accounts for the bleeding.
• Animals often recover, but have a low feed conversion ratio for sometime.

Diagnosis

• Silver stains show organisms in the epithelium of the mucosa.
• Also by immunofluorescence or electron microscopy.

Parvovirus Enteritis

• Parvovirus enteritis is also know as feline infectious enteritis or feline panleucopenia
• Since a vaccine is available, this disease is now uncommon.
• Over the last 10/15 years this has been seen primarily in the cat, but it is now also seen in the dog.

Clinical

• Manifests mainly in cats under 6 months old.
• Common in groups of unvaccinated cats.
  • Produces big outbreaks, with vomiting and pyrexia.
• Severe vomiting and diarrhoea occur.
  • diarrhoea is thin, watery and foul-smelling, and may also be blood-tinged.
    • Animals usually die despite treatment- die from dehydration.
• Animals suffer from fever.
• Pancytopaenia also occures.
  • White blood cell count drops very low so as to become almost non-existent.
    • Drops to 1/ml from 10000/ml.
  • Animals may therefore also die from other infections.

Pathology

Gross

• Virus targets crypt cells and lymphoid areas.
  • Causes villus atrophy.
• In the cat, the intestine is thickened, turgid and swollen.
  • Has a pale, dull and mottled appearance.
  • The contents are rather dry - this gets worse lower down the gut.
• Areas of depression in the mucosa can be seen in the upper small bowel.
  • Due to necrosis of tissue overlying Peyers patch.
• Lower down in the gut, enteritis is apparent.
  • Cat- fibrinous.
  • Dog- haemorrhagic.
    • Blood in lumen.
  • Inflammation sometimes doesn't appear very severe.
• There may be very few lesions
  • Histology is usually required for diagnosis.
• A radiomimetic virus.
  • Affects all rapidly dividing cells and destroys them.
    • E.g. epithelium in the base of the crypts of small intestine are killed.

Histological

• The crypt lining cells undergo complete necrosis, but very little inflammation occurs.
  • Collapse of villous architecture.
• May be fibrinous exudates on surface of mucosa.
• The submucosa and lamina propria are not affected and are left intact.
  • Many neutrophils in the lamina propria.
• Cyst-like structures are seen in the deepest parts of the glands of the intestinal mucosa, if the animal survives for more than a few days.
  • Flattened epithelial cells line these cystic glands.
    • Are enterocytes trying to repair the damage.
    • However, animals usually die from dehydration or secondary infection before the mucosa recovers.
• Inclusion bodies may be seen, but these are very hard to find.
• May get lymphocyte invasion of mucosa.
• Lymph nodes appear pale and oedematous, and almost aplastic.
• Bone marrow appears pale and fatty looking and is depleted of cells.

Canine Disease

• Until 1978 Parvovirus enteriris was totally unknown in dogs.
• First seen in dogs in Australia.
  • Apeared very similar but perhaps slightly worse than the disease seen in the cat.
  • A new and distinct disease, but the virus is very closely related to the feline virus.
    • Viral DNA is 98% homologous to the feline virus.
  • The canine virus does NOT cause disease in cats.
• Clinical
  • Causes enteritis in young dogs over 6 weeks old.
  • Causes myocarditis in puppies.
  • Mainly affects the small intestine.
• Vaccines are very effective, but the virus is hardy and survives in the environment.
• Diagnosis:
  • Look for viral antigen in the faeces by the red cell agglutination test.
  • Immunoflurescence.
  • ELISA.
  • Serology.

Bacterial septicaemia and enteritis

• Some severe acute septicaemias cause very severe acute haemorrhagic enteritis with bleeding into the alimentary tract.
• Death is usually rapid.
• Fairly easy to diagnose
  • small intestine is full of dark, tarry, partly clotted blood (like black currant jelly).
• Associated with severe systemic disease, e.g.
  • Anthrax in cattle (Bacillus anthracis).
  • Leptospirosis in dogs.
    • Especially L. icterohaemorrhagiae.
• Do not confuse with warfarin poisoning.
  • Also gives blood in stomach and intestine BUT there are no signs of inflammatory disease.

Lamb Dysentery (Enterotoxaemia with Blood)

• Clostridium perfringens causes very severe acute haemorrhagic enteritis.
  • Usually affects young farm animals
    • May also be seen in pets.
• Type B Clostridium perfringens infection of lambs leads to lamb dysentery.

Clinical

• Lamb dysentery is usually seen in lambs under 2 weeks of age.
  • Related to being kept in a cold, dirty environment, with build-up of infection during the lambing season.
• Lambs may produce bloodstained diarrhoea before death, but they often die before this effect is apparent.
• Diagnosed by culturing contents of gut.

Pathology

Gross

• The gut is blown and distended with foamy ,bloody contents.
• Sometimes ulceration with perforation and fibrinousperitonitis is seen.
• Focal or diffuse congestion and haemorrhages.

Histological

• Coagulative necrosis of villi.
• Oedema.
• Haemorrhage.
• Influx of inflammatory cells in the lamina propria and submucosa.

Similar Conditions

• Piglets show similar disease caused by Clostridium perfringens type C (and sometimes type B)
  • May look similar to a volvulus but with no twist present.
• In adult sheep Clostridium perfringens type B infection causes Struck.
  • Enterotoxigenic gastritis.
  • Acute sudden death with haemorrhagic enteritis
  • Haemorrhagic enteritis is not as severe as in lambs, and tends to be more patchy.

Colitis X

• Affects the horse.
• Sudden onset with haemorrhages throughout body (shock) and sometimes acute foul smelling diarhoea.
• colon is acutely haemorhagic and oedematous with mucosal necrosis.
• Associated with Clostridium perfringens.
• Possibly an enterotoxaemia.