Peritonitis - Cats and Dogs

Signalment

No breed predisposition.
No sex predilection.
No specific age distribution.

Description

Peritonitis is defined as the inflammation of the peritoneum, which can be septic or non-septic. The inflammatory process leads to vasodilation, cellular infiltration, pain and adhesion.

Septic peritonitis results from free bacteria in the peritoneal cavity, caused by perforation of the gastrointestnal tract due to foreign bodies, necrosis secondary to obstruction, intussusception, neoplasia, foreign bodies or dehiscence. Peritonitis as a result of wound dehiscence is most likely to occur 3-5 days post-operatively.

Non-septic, also known as chemical peritonitis, may be the result of leakage of bile, urine or pancreatic enzymes. However, non-septic peritonitis can cause septic peritonitis, for example cases where septic urine is present.

Diagnosis

Clinical Signs

Abdominal pain
Depressed
Vomiting
Tachycardia
Tachypnoea
Hypotension and shock
Hypothermia or hyperthermia

Laboratory Tests

Haematology

Neutrophilia ± left shift or neutropaenia
Haemoconcentration
Hypoproteinaemia

Biochemistry

Hypoglycaemia - possible sepsis
Increased lactate concentration
Azotaemia
Hypokalaemia
Metabolic acidosis

Diagnostic Imaging

Radiography

Abdominal radiography may reveal free gas in the abdomen. This is highly suggestive of peritonitis. The serosal details may be loss. If taken with the patient standing, a fluid line may be seen.
Thoracic radiograph should be assessed for signs of metastatic disease.

Ultrasonography

This is senstive for any free fluid in the abdomen.
Possible causes such as abscesses of organs or rupture of gallbladder can be identified.

Histopathology

Abdominal fluid can be collected for laboartory analysis via abdominocentesis. The fluid should be stained for intracellular bacteria and assessed for:
- amylase and lipase for pancreatitis
- bile for biliary leak
- creatinine for urine
- glucose (<2.8 mmol/l) and lactate (>5.5 mmol/l) for sepsis

Treatment

It is vital to identify cases which require emergency surgical intervention. Any of the following is a major indication:

positive for intracellular bacteria.
free gas visible in the abdominal radiograph.
presence of penetrating injuries in the abdomen.

Fluid therapy

Aggressive fluid therapy with crystalloid and colloid should be given on initial presentation to improve haemodynamic parameter.
Fluid therapy is also very important in the postoperative period. Both crystalloid and colloid should be continued until the the patient is normotensive. However, if hypotension continues, a vasopressor such as vasopressin should be considered.
Supplementaion of glucose and potassium may be needed.

Analgesia

Opiods should be given.

Antimicrobial

Broad spectrum antibiotics should be given, preferably following culture and sensitivity test.

Prognosis

Guarded. Peritonitis is a multifactorial disease and the consequence if fatal in most cases. A rapid diagnosis and treatment may improve the prognosis.

References

Ettinger, S.J. and Feldman, E. C. (2000) Textbook of Veterinary Internal Medicine Diseases of the Dog and Cat Volume 2 (Fifth Edition) W.B. Saunders Company.
Hall, E.J, Simpson, J.W. and Williams, D.A. (2005) BSAVA Manual of Canine and Feline Gastroenterology (2nd Edition) BSAVA
Nelson, R.W. and Couto, C.G. (2009) Small Animal Internal Medicine (Fourth Edition) Mosby Elsevier.

For further information on peritonitis see: [1] In Practice article