The dog or cat with septic peritonitis may display evidence of sepsis, severe sepsis, septic shock, and frequently, multiple
organ dysfunction. Septic peritonitis is a rapidly progressive clinical syndrome with an array of underlying etiologies. Early
recognition accompanied by rapid medical stabilization, early surgical intervention, and diligent postoperative care is crucial
to optimize the likelihood of a positive outcome.
Etiology and Presenting Complaints in Small Animals with Septic Peritonitis:
Septic peritonitis most commonly results from disruption of the gastrointestinal tract, however, ruptured uterus or prostatic
abscess, penetrating injury, urinary tract disruption, bile leakage, hepatic or splenic abscesses, and sepsis can all result
in this immediately life-threatening condition. Common presenting complaints include vomiting, lethargy, anorexia, diarrhea,
Septic peritonitis should also be on the list of differential diagnoses for any patient that has recently undergone
Diagnosis of Septic Peritonitis
Physical examination findings are centered on acute abdominal pain, dehydration, fever, and shock (likely a combination of
hypovolemic and septic/distributive).
Cytologic evaluation of abdominal fluid samples has been the diagnostic test of choice for the acute diagnosis of septic
peritonitis in dogs and cats. Cytologic evaluation alone is considered to be 57-87% accurate in making the diagnosis. Samples
can be collected via abdominocentesis, four quadrant abdominocentesis, paracentesis with a peritoneal lavage catheter, and
diagnostic peritoneal lavage (DPL). DPL is recognized to be superior to other methods for the acute diagnosis of significant
intraperitoneal disease or injury.5 Samples collected by DPL should be centrifuged prior to evaluation in order to concentrate the cellular material for analysis.
Samples collected for cytologic and biochemical evaluation should also be saved for aerobic and anaerobic culture. Early gram-stain
procedures will help direct empirical antibiotic therapy while culture is pending.
A recent study evaluated the utility of blood glucose gradients between the abdominal fluid and the blood in an effort to
find a highly sensitive and specific mechanism for the rapid diagnosis of septic peritonitis. Biochemical tests such as glucose
determination must be performed on samples acquired directly from the peritoneum rather than from DPL samples. The authors
concluded that a gradient of >20mg/dL between the blood and the abdominal fluid (the abdominal fluid will be less than the
blood) was 100% sensitive and specific in dogs for the diagnosis of septic peritonitis. In cats, the same gradient was 86%
sensitive and 100% specific for the diagnosis of septic peritonitis. This study should be interpreted with some caution due
to small sample size and decreased sample heterogeneity. Of particular concern was the fact that the low glucose in the abdominal
fluid samples may have been a reflection of the increased cellularity of the septic samples compared to the non-septic samples,
rather than the presence of bacteria.
Suggestive historical and physical examination findings supported by cytologic and biochemical evidence should prompt surgical
intervention as soon as patient stability is achieved. Aggressive fluid therapy (isotonic crystalloid and colloid therapy)
and early antibiotic therapy are cornerstones of stabilization. Normalization of blood pressure, blood glucose, and other
physiologic abnormalities should be attempted prior to anesthetic induction.