Peritonitis

See also:

Peritonitis in Dogs and Cats

Description

Peritonitis refers to inflammation of the peritoneal cavity and it may occur in any of the domestic species. Peritonitis represents a considerable therapeutic challenge in any species and frequently carries a very poor prognosis.

Classification

Peritonitis may be classified in a number of ways depedning on its cause, the nature of the inflammatory exudate formed, the extent of the disease and the chronicity with which it develops.

The inflammation may affect the entire peritoneal cavity (generalised or diffuse) or it may affect just one part of the cavity (localised). The formation of fibrous adhesions in chronic peritonitis may isolate the inflammation in one particular area of the cavity.

Different pathological processes result in the formation of different type of inflammatory exudate depending on the degree to which the peritoneal vasculatur is damaged and on the types of leucocyte which migrate to the site of the inflammation. The following types of peritonitis are recognised based on the nature of the exudate:

• Sero-fibrinous e.g. Glasser’s disease (Haemophilus parasuis) in pigs
• Fibrinopurulent e.g. after gut rupture, systemic infection (pasteurellosis in sheep)
• Purulent e.g. Rhodococcus equi in foals
• Haemorrhagic e.g. splenic rupture
• Granulomatous e.g. Nocardia in dogs

Peritonitis may occur acutely or it may be a chronic process that has reached an advanced stage before it is diagnosed. In cases of acute peritonitis, there is likely to be increased amounts of fluid in the peritoneal cavity and roughening of serosal surface of the abdominal organs and parietal peritoneum due to the presence of fibrin. Cases of chronic peritonitis often involve fibrous adhesions between any of the abdominal organs and the omentum, mesentery or peritoneum.

Causes of peritonitis

• Usually secondary to other abdominal pathology but may be primary
• Septic or non-septic

Chemical

Image of bile stained peritonitis in a cat from Cornell Veterinary Medicine

e.g.:

• Bile
• Urine
• Pancreatic enzymes (acute pancreatic necrosis)
• Barium if allowed to leak into peritoneal cavity (causes potentially fatal haemorrhagic peritonitis)
• Surgical glove powder (granulomatous peritonitis)
• Chyle (mild granulomatous serositis)

Bacterial

Tuberculous peritonitis with phagocytosis of lymphocytes (Sourced from Bristol Biomed with permission)

e.g.:

• Penetrating wound
• Gut rupture
• Surgery
• Inflammatory focus e.g. abscess, bacteraemia
• Umbilicus
• Gangrenous intestine or uterus prior to rupture

Viral

Image of FIP by Cornell Veterinary Medicine

e.g.

• Feline infectious peritonitis - in “wet” (effusive) form, sero-fibrinous fluid with high protein (Ig content), tags of fibrin attach to peritoneum and organs

Parasites

e.g.

• Strongyle migration in horses
• Fasciola hepatica - lesions around liver
• See Peritoneal Cavity Parasitic

Sequelae to peritonitis

• Hypermotility initially → hypomotility
  • Ileus - reduces distribution of exudates by intestinal motility
  • Fibrinous adhesions may develop
• Impaired CV function and acid-base imbalance
  • Due to sequestration of fluid and protein in exudate, hypomotile gut, bacterial exo/endotoxins absorbed directly from peritoneal cavity and causing vascular permeability, loss of intestinal absorption
• May resolve, become chronic-active or lead to adhesions.

In dogs

• Fibrinohaemorrhagic peritonitis in infectious canine hepatitis
• Septic peritonitis caused by various agents, often Escherichia coli and anaerobic bacteria through perforation of the gut, rupture of urinary bladder or an abscess
• Putrid peritonitis in uterine rupture with pyometra or septic metritis
• Nocardia infection reults in profuse pink/red fluid due to blood and chronic inflammatory cells
• Granulomatous peritonitis caused by fungi, Nocardia and Actinomyces

In cats

• Putrid peritonitis in uterine rupture due to pyometra or fetal putrefaction
• Peritonitis due to penetrating wounds
• Septic peritonitis due to anaerobes in cat bite abscesses
• Serous peritonitis in cats with feline infectious peritonitis especially in the wet form but exudate occurs also in the dry form
  • Viscous, clear, pale to deep yellow fluid, may contain strands of fibrin

In horses

Image of acute fibrinous peritonitis in a horse from Cornell Veterinary Medicine

• Diffuse acute peritonitis often fatal
• Mostly caused by rupture of stomach or intestine
• In foals purulent peritonitis may be caused by Rhodococcus equi or fibrinous peritonitis by Actinobacillus equuli
• Haemorrhage as a consequence of castration may result in acute non-septic
• Secondary to verminous lesions

In cattle

• Perforation of an abdominal organ, usually reticulum or [[uterus, results in acute diffuse fibrinopurulent peritonitis or local acute and chronic, with adhesions
• Traumatic reticuloperitonitis (hardware disease) may evolve into reticulopericarditis
• Local chronic peritonitis, abscesses containing usually Actinomyces pyogenes
• Fibrinopurulent peritonitis through umbilical infection in calves
• Fibrinous peritonitis in calves with septicaemic colibacillosis
• Serofibrinous peritonitis in sporadic bovine encephalomyelitis
• Diffuse fibrinohaemorrhagic peritonitis in clostridial haemoglobinuria
• Localised peritonitis in clostridial enterotoxaemia (Clostridium perfringens types B and C and braxy)

In sheep

• Fibrinopurulent peritonitis in postpartum septic metritis
• Serofibrinous peritonitis in diseases caused by Mycoplasma
• In penetration of intestines by larvae of Oesophagostomum columbianum

In goats

• Acute fibrinous peritonintis caused by Mycoplasma mycoides

In pigs

• Diffuse fibrinopurulent peritonitis in infections by Actinomyces pyogenes, Escherichia coli or other organisms
• Serofibrinous peritonitis in Glasser’s disease Haemophilus parasuis or Mycoplasma or septicaemias caused by Streptococcus suis type 2
• Acute gelatinous haemorrhagic peritonitis in Anthrax

References

Image of acute fibrinous peritonitis from Cornell Veterinary Medicine