Objective: To describe and compare the patient population, treatment, and outcome in dogs with septic peritonitis from 2 time periods at the same institution.Design: Retrospective study.Setting: The Matthew J. Ryan Veterinary Hospital at the University of Pennsylvania.Animals: Dogs treated surgically for septic peritonitis between 1988–1993 and 1999–2003.Interventions: None.Measurements: Preoperative physical and clinicopathologic data, surgical findings, anesthetic parameters, treatment, and outcome.Main results: No significant difference in survival among dogs treated surgically for septic peritonitis between 1988 and 1993 (21/33 [64%]) and 1999–2003 (29/51 [57%]) was detected. The patient populations of the two time periods were similar. Changes in treatment between the study periods reflected availability of new antibiotics and synthetic colloids, as well as greater attention to pain management and ulcer prevention. Duration of hospitalization was not significantly different between the two time periods, but the daily cost adjusted to 2005 dollars was higher in 1999–2003. Potential prognostic indicators were compared between survivors and non‐survivors after combining the data from both time periods, and although several parameters reached statistical significance, of greatest clinical significance were the higher blood pressure and preoperative serum albumin in survivors.Conclusions: Although new treatments were added to the supportive care of dogs with septic peritonitis, survival did not change sufficiently to detect a significant difference between the time periods evaluated. Identifying reliable prognostic indicators for septic peritonitis remains a challenge, but hypotension and decreased preoperative serum albumin were associated with non‐survival in this group of dogs.

Four dogs were examined because of vomiting of 7 to 48 hours' duration. Gas-distended segments of intestine were identified radiographically in all dogs, but the affected portion of the intestinal tract could not always be identified as the colon. Volvulus of the colon was diagnosed during surgery in all 4 dogs. Gastrocolopexy was performed following derotation of the colon in 3 of the dogs. In 1 dog, a colectomy and an ileorectal anastomosis were performed. All 4 dogs survived. Volvulus of the colon should be considered as a cause of vomiting of short duration in dogs for which there is radiographic evidence of intestinal dilatation.

Deficiencies of PC and AT and hypercoagulability appear to be consistent features of naturally occurring canine sepsis and may be useful prognostic indicators in canine septic peritonitis.

In vitro hypercoagulability was commonly detected in dogs with naturally occurring EHBO. The traditional view of EHBO as a disease that causes hypocoagulability may need to be reconsidered.

For the patients in the present study, there was an increased odds of GDV in dogs with a history of splenectomy. Prophylactic gastropexy may be considered in dogs undergoing a splenectomy, particularly if other risk factors for GDV are present.