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Recurrence of septic peritonitis in dogs | VETgirl Veterinary CE Podcasts

Do you treat patients with septic peritonitis in your clinic? If you do, do you agonize over them for the first few days after surgery, worried that they will require a second surgery due to recurrence (Is this dog going to perf!)? Have you thought about what factors might put these patients at risk for recurrence?

In today’s VETgirl online veterinary continuing education podcast, we review the recurrence of septic peritonitis in dogs. Septic peritonitis occurs most commonly in our veterinary patients due to gastrointestinal sources, but can also occur secondary to leakage of infected contents of the biliary system, urogenital system, or infected masses or abscesses elsewhere in the abdomen. Prognosis for these patients is guarded, with mortality rates ranging from 20-46%. For cases that have a recurrence of peritonitis following a first surgery, many of us might worry that their prognosis is even worse, or that certain factors, such as hypoproteinemia, put them at increased risk.

So Barfield et al out of the Royal Veterinary College, Tufts Veterinary and Michigan State University wanted to investigate the outcome in dogs with recurrent secondary septic peritonitis (RSSP), defined as “persistent or recurrent septic peritonitis following adequate surgical source control for secondary bacterial peritonitis.” (Secondary peritonitis has an identifiable source of intraperitoneal infection). They also wanted to look at risk factors for RSSP. So they looked for cases of RSSP retrospectively and identified 41 dogs total, based on positive culture from the peritoneal effusion, cytological identification of intracellular bacteria from peritoneal effusion, or visible evidence of continued leakage at re-laparotomy or during open abdomen management. In this study, the median age was 5.0 years (range: 0.7-12) with no difference between survivors and non-survivors. The median time between the first and second surgeries was 3 days (range 1-7), with no difference between survivors and non-survivors (p=0.46). Causes of RSSP included gastrointestinal foreign body (which perforated or dehisced post-op) in 26 dogs (63.4%), GI neoplasia in 3 dogs (7.3%), gastric or duodenal ulceration in 3 dogs (7.3%), biliary tract leakage in 2 dogs (4.9%), and in 1 dog each: penetrating foreign body, hernia strangulation, intussusception, mesenteric volvulus, infection of the linea alba incision, prostatic abscess and trauma.

In this study, they found that dogs with RSSP due to gastrointestinal foreign bodies had a 50% mortality rate (13/26), and dogs without foreign bodies had a 66% mortality rate (10/15); however, there was no statistical difference between these groups (p=0.24). Most of the cases of RSSP had contamination from GI sources (37 dogs; 90.3%), while the rest had rarer sources such as biliary (2 dogs; 4.9%), prostate (1 dog, 2.4%) and surgical incision (1 dog, 2.4%). There was no difference in survival between patients managed with a closed (15/34) or open (3/7) abdomen (p=0.64). The median albumin concentration at initial presentation was 1.81 g/dL in survivors and 1.92 g/dL in non-survivors, with no difference between the groups (p=0.068). Cultures, when performed, most commonly grew E. coli (65.8%, 25/38 dogs). In this study, 8/18 dogs treated with appropriate antibiotics survived, and 7/16 treated with inappropriate antibiotics survived (no difference, p=0.59). Overall, 18/41 dogs (43.9%) survived to discharge; the remaining 23 either died or were euthanized.

So, what can we take away from this VETgirl podcast? While this study found a high mortality rate for dogs with RSSP (56.1%), it is similar to reports in the veterinary literature for dogs with septic peritonitis (29-46%), suggesting that canine patients requiring a second surgery do not have a worse prognosis. The timing of the second surgery was an interesting point in this paper, with most patients requiring a second surgery within a median of 3 days. The authors speculate that patients requiring a second surgery within 48 hours are more likely to have had technical failure or inadequate source control compared to patients outside of the 48 hour time frame. Unfortunately, in this study, the most common cause of RSSP in these patients was GI leakage secondary to foreign body ingestion, either from perforation of the foreign body or dehiscence after surgery… definitely something to warn pet owners about the next time you’re going in for a “simple” foreign body surgery.

Interestingly, while we often worry about low albumin being an issue for tissue healing and a risk factor for dehiscence, this study did not find that to be the case, as there was no difference in albumin concentrations between survivors and non-survivors. Also, implementation of appropriate antibiotics versus inappropriate antibiotics based on culture results didn’t affect outcome in these patients (That said, let’s still be judicious with our antibiotic therapy and base it appropriately on Gram stain or source of infection). Barfield et al hypothesized that source control with copious lavage at surgery may have helped in these patients, but they also couldn’t determine if antibiotics were changed based on culture results; this was likely a limitation of this being a retrospective study.

The most interesting finding in this study was that patients with RSSP have a fairly similar prognosis to patients who require a single surgery for septic peritonitis, so don’t condemn them! It would have been interesting to see more discussion regarding management of these cases (e.g., closed abdomen, closed abdomen with surgical drain, open abdomen) with details on daily monitoring and how samples were obtained for cytology and culture. However, given the retrospective nature of the study, it may be a better topic for a prospective project. So, to conclude, this study suggests that the survival rate for dogs with recurrent septic peritonitis is similar to that of dogs requiring a single surgery. Age, time to RSSP, open or closed abdominal management, antimicrobial appropriateness and albumin concentrations were not associated with outcome.

Abbreviations:
RSSP: recurrent secondary septic peritonitis

References:
1. Barfield DM, Tivers MS, Holahan M et al. Retrospective evaluation of recurrent secondary septic peritonitis in dogs (2000-2011): 41 cases. J Vet Emerg Crit Care 2015; early online release.

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