Impact of appropriate empirical antimicrobial therapy on outcome of dogs with septic peritonitis

Diagnostic utility of the total nucleated cell count for differentiation of septic and sterile peritoneal effusions in dogs

BACKGROUND

Rapid and accurate diagnosis of septic peritonitis is critical for initiating appropriate medical and surgical management.

OBJECTIVES

The aim of this study was to determine the diagnostic utility of the total nucleated cell count (TNCC), absolute neutrophil count, neutrophil percentage, and total protein (TP) to distinguish septic versus non-septic peritoneal effusions in dogs.

METHODS

Electronic medical records were retrospectively searched for peritoneal fluid samples from 2008 to 2018 and classified as septic or non-septic based on bacterial culture and/or cytology results. Receiver operator characteristic curves (ROCs) were used to describe the overall diagnostic utility of each test, with optimal cutpoints analyzed to dichotomize continuous variables. Positive and negative likelihood ratios were calculated at these cutpoints.

RESULTS

A total of 166 unique samples, including 87 septic and 79 non-septic peritoneal effusions, were included. There were no significant differences in dog sex, age, or days hospitalized between groups. Septic effusions had significantly higher TP, TNCC, absolute neutrophil count, and neutrophil percentage compared with non-septic effusions. The area under the curve of the ROC curves was TNCC (0.80), absolute neutrophil count (0.80), neutrophil percentage (0.64), and TP (0.63). For TNCC and absolute neutrophil count, optimal cutoffs were 17.13 × 103  cells/μL and 19.88 × 103  cells/μL, resulting in positive and negative likelihood ratios of 2.39 and 0.28 and 2.85 and 0.28, respectively.

CONCLUSIONS

Total nucleated cell counts and absolute neutrophil counts aid in the differentiation of septic and non-septic peritoneal effusions with similar diagnostic utility but are not sufficiently sensitive or specific to use without concurrent microscopic evaluation.

Association of the origin of contamination and species of microorganisms with short-term survival in dogs with septic peritonitis

OBJECTIVE

To assess the association between anatomical location of contamination and mortality in dogs with gastrointestinal and biliary origin of septic peritonitis.

METHODS

Medical records at two private referral hospitals between 2003 and 2020 were retrospectively reviewed. Cases were included if the origin of contamination was confirmed intraoperatively within the gastrointestinal or biliary tract. Cases were excluded if the dog died or was euthanized intraoperatively or where the data regarding the origin of contamination were not available. The association of anatomical origin with survival was assessed specifying the locations as stomach, small intestine, large intestine and biliary tract. The gastrointestinal tract origin was further subdivided into pylorus, nonpylorus, duodenum, jejunum, ileum, caecum and colon.

RESULTS

The overall survival rate was 75.9% (n = 44/58). There were no significant differences in survival among different anatomical origins of contaminations before or after subdivision (P = 0.349 and 0.832, respectively). Also, there was no association between isolated microorganism species in microbiological culture and the anatomical origin (P = 0.951) and the microorganism species was not associated with survival (P = 0.674).

CONCLUSIONS

There was no association between anatomical location of leakage, microorganism species and survival although further studies are warranted to analyse the relationships between anatomical leakage site and microorganism species as well as microorganism species and mortality.

Outcome in 38 dogs surgically treated for hepatic abscessation

OBJECTIVE

To report outcomes following surgical treatment of hepatic abscessation in dogs.

STUDY DESIGN

Retrospective.

ANIMALS

Thirty-eight dogs.

METHODS

Records from 6 institutions were evaluated for dogs undergoing surgical treatment for hepatic abscessation between 2010 and 2020. Signalment, clinical signs, medical therapy, surgical treatment, and postoperative outcome was obtained from medical records. Long-term outcome was recorded when possible. Median survival time was assessed using the Kaplan-Meier product-limit method.

RESULTS

Peritoneal effusion was documented in 32/38 dogs preoperatively, with septic peritonitis confirmed in 21/23 samples. Liver lobectomy was the most common surgery (27 dogs). A single organism was cultured in 24/35 dogs, most commonly Escherichia coli. Hepatic neoplasia was identified in 11/36 dogs. Dogs were hospitalized for a median of 5 days (range, 3-17) with complications recorded in 21 dogs (regurgitation, aspiration pneumonia, and pancreatitis most commonly). Two dogs died intraoperatively, and 6 dogs died prior to discharge. Median survival time for dogs surviving to discharge was 638 days. Of these, 19 were lost to follow up a median of 301 (range, 3-1418) days postoperatively and 11 died a median of 291 (range, 7-1292) days postoperatively. No abscess recurrence was noted.

CONCLUSION

Septic peritonitis was a common sequela to hepatic abscessation. Perioperative complications were recorded in approximately one-third of dogs. In dogs surviving the postoperative period, long-term prognosis was good.

CLINICAL SIGNIFICANCE

Dogs treated surgically for hepatic abscessation have a high risk of perioperative complications but favorable long-term prognosis and apparent low risk of recurrence.

Effect of antimicrobial administration on fecal microbiota of critically ill dogs: dynamics of antimicrobial resistance over time

Background

Multidrug resistance in companion animals poses significant risks to animal and human health. Prolonged antimicrobial drug (AMD) treatment in animals is a potential source of selection pressure for antimicrobial resistance (AMR) including in the gastrointestinal microbiota. We performed a prospective study of dogs treated for septic peritonitis, pyometra, or bacterial pneumonia and collected repeated fecal samples over 60 days. Bacterial cultures and direct molecular analyses of fecal samples were performed including targeted resistance gene profiling.

Results

Resistant Escherichia coli increased after 1 week of treatment (D1:21.4% vs. D7:67.9% P < 0.001) and returned to baseline proportions by D60 (D7:67.9% vs D60:42.9%, P = 0.04). Dogs with septic peritonitis were hospitalized significantly longer than those with pneumonia or pyometra. Based on genetic analysis, Simpson’s diversity index significantly decreased after 1 week of treatment (D1 to D7, P = 0.008), followed by a gradual increase to day 60 (D1 and D60, P = 0.4). Detection of CTX-M was associated with phenotypic resistance to third-generation cephalosporins in E. coli (OR 12.1, 3.3–68.0, P < 0.001). Lincosamide and macrolide-resistance genes were more frequently recovered on days 14 and 28 compared to day 1 (P = 0.002 and P = 0.004 respectively).

Conclusion

AMR was associated with prescribed drugs but also developed against AMDs not administered during the study. Companion animals may be reservoirs of zoonotic multidrug resistant pathogens, suggesting that veterinary AMD stewardship and surveillance efforts should be prioritized.

Graphical abstract

Supplementary Information

The online version contains supplementary material available at 10.1186/s42523-022-00178-9.

Serial analysis of blood biomarker concentrations in dogs with pneumonia, septic peritonitis, and pyometra

BACKGROUND

Prolonged antimicrobial drug (AMD) treatment is associated with antimicrobial resistance development. Biomarker measurement may aid treatment decision-making.

OBJECTIVES

Investigate temporal changes in blood biomarker concentrations in dogs undergoing treatment for pulmonary and intra-abdominal infections; compare time to biomarker concentration normalization with duration of clinician-directed AMD treatment.

ANIMALS

Forty-two client-owned dogs with pneumonia (n = 22), septic peritonitis (n = 10), or pyometra (n = 10).

METHODS

Plasma concentrations of C-reactive protein (CRP), serum amyloid A (SAA), haptoglobin, procalcitonin, nucleosomes, cell-free DNA (cfDNA), high-mobility group box-1 (HMGB1), CC-motif chemokine ligand-2 (CCL2), CXC-motif chemokine ligand-8 (CXCL8), and keratinocyte chemoattractant-like (KC-Like) were quantitated in samples collected on days 1, 3, 7, 14, 28, and 60. Treatment was directed by clinicians blinded to biomarker concentrations.

RESULTS

Concentrations of CCL2, CRP, and KC-Like were maximal on D1, concentrations of SAA, cfDNA, HMGB1, and nucleosomes were maximal on D3 and haptoglobin concentrations were maximal on D7. These maximal concentrations were significantly different from those on D60. Concentrations of CRP and SAA decreased by 80% from peak and into respective reference intervals before AMDs were discontinued. For CRP, the median (interquartile range [IQR]) times to 20% peak and normal were 7 (6-9) and 7 (6-12) days, respectively, and for SAA they were 4 (4, 5) and 6 (5-8) days, respectively, compared to a median (IQR) duration of AMD prescribing of 16 (12-23) days (all P < .0001).

CONCLUSIONS AND CLINICAL IMPORTANCE

Biomarker concentrations normalized within 7 to 14 days. Serial measurements of CRP and SAA might aid identification of disease resolution and could help guide AMD prescription decision-making.

Clinical features, outcome, and illness severity scoring in 32 dogs with urosepsis (2017-2018)

OBJECTIVE

To describe the clinical features, outcome, and utility of illness severity scoring in dogs diagnosed with urosepsis.

DESIGN

Retrospective study (2017-2018).

SETTING

University teaching hospital.

ANIMALS

Thirty-two dogs diagnosed with urosepsis secondary to pyometra, prostatitis, or pyelonephritis.

INTERVENTIONS

 None.

MEASUREMENTS AND MAIN RESULTS

Urosepsis was identified in 32 dogs, consisting of 9 of 32 (28.1%) with pyometra, 7 of 32 (21.8%) with prostatitis, and 16 of 32 (50%) with pyelonephritis. In total, 28 (87.5%) dogs survived to discharge, with the following group-specific survival rates: pyometra, 9 of 9 (100%); prostatitis, 5 of 7 (71.4%); and pyelonephritis, 14 of 16 (87.5%). Positive bacterial cultures were obtained in 27 of 32 (84.1%) dogs. The most commonly implicated pathogens were Escherichia coli (14/37 [37.8%]), Klebsiella pneumoniae (8/37 [21.6%]), and Staphylococcus pseudintermedius (6/37 [16.2%]). Multiple organ dysfunction syndrome (MODS) was identified in 21 of 32 dogs (65.6%). Although the presence of MODS was not different between survivors and nonsurvivors (P = 0.6), nonsurvivors had more dysfunctional organs (P = 0.04). Nonsurvivors also had higher Acute Patient Physiology and Laboratory Evaluation (APPLE_FAST ) scores compared to survivors (P = 0.01).

CONCLUSIONS

Survival of dogs with urosepsis was good and may be higher than for other sources of sepsis. Compared to survivors, nonsurvivors had more dysfunctional organs and higher illness severity scores, which may be helpful in the assessment and management of dogs with urosepsis.

Classification of Septic Shock Phenotypes Based on the Presence of Hypotension and Hyperlactatemia in Cats

Background: Three different phenotypes of septic shock based on changes in blood pressure and lactate are recognized in people. Dysoxic shock, representing the combination of fluid-refractory hypotension and hyperlactatemia, is characterized by greater disease severity and mortality compared to cryptic shock (hyperlactatemia alone) and vasoplegic shock (hypotension with normal blood lactate). Little is known about septic shock and specifically its phenotypes in cats. Objective: To analyze the characteristics and prognostic implications of three septic shock phenotypes in cats with sepsis. Methods: Cats with septic shock were prospectively included. Septic shock was defined by the presence of hypotension (mean blood pressure <60 mmHg) requiring vasopressor support and/or persistent hyperlactatemia (>4 mmol/L) and classified in three subgroups: dysoxic shock, vasoplegic shock and cryptic shock. Clinical and clinicopathological variables including APPLE_fast and APPLE_full scores, occurrence of multi-organ dysfunction syndrome (MODS; presence of at least two dysfunctional organs simultaneously) and outcome were compared among subgroups. Cats with sepsis showing normal blood pressure and lactate concentrations hospitalized during the study period were included as uncomplicated sepsis, and compared to cats with septic shock for selected variables. Length of hospital stay and mortality were evaluated in the whole study population. Odds ratios for mortality were calculated using logistic regression analysis. Significance was set at P < 0.05. Results: The study enrolled 48 cats with uncomplicated sepsis and 37 cats with septic shock (dysoxic shock n = 17; vasoplegic shock n = 11; cryptic shock n = 7). Cats with dysoxic shock had significantly higher APPLE_fast and APPLE_full scores compared to vasoplegic and cryptic shock. Mortality rates were not significantly different among cryptic (57%), dysoxic (65%) and vasoplegic shock (91%), while MODS occurrence was significantly lower in cats with cryptic shock (57%) compared to patients affected by dysoxic (94%) and vasoplegic (100%) shock. Cats with septic shock had higher frequency of MODS and greater mortality rate than cats with uncomplicated sepsis. Conclusion: Despite similar in-hospital mortality, cats with dysoxic and vasoplegic shock are characterized by having higher occurrence of multi- organ dysfunction compared to cats affected by cryptic shock. Results from this study suggest novel means of identifying high-risk subgroups of septic cats.

A feasibility study investigating the utility of a point-of-care rapid immunoassay for detecting septic peritoneal effusion in dogs

OBJECTIVE

To determine the sensitivity (SN), specificity (SP), positive predictive value (PPV), negative predictive value (NPV), and accuracy of a point-of-care urine bacterial rapid immunoassay (RIA) for a diagnosis of septic peritonitis, compared to more traditional diagnostic tools, such as cytology and bacterial culture.

DESIGN

Prospective, cross-sectional feasibility study conducted from October 2016 to June 2017.

SETTING

Four locations within a private practice referral hospital.

ANIMALS

Sixty-four dogs with peritoneal effusion of any etiology were enrolled. Four dogs were excluded due to absent RIA or bacterial culture results. Two additional dogs were excluded because of an inability to definitively classify them as having septic peritonitis.

INTERVENTIONS

Abdominocentesis was performed to obtain peritoneal effusion samples for aerobic and anaerobic bacterial culture, cytology, and RIA. Cytological slides were evaluated by a clinical pathologist following enrollment.

MEASUREMENTS AND MAIN RESULTS

Fifty-eight dogs were included in the study, 8 of which were classified as having septic peritonitis. Compared to final diagnosis of septic peritonitis, RIA had a low PPV (36.8%) but good NPV (97.4%) and was 77.5% accurate. SN of RIA (87.5%) to diagnose septic peritonitis was similar to cytology (85.7%) and bacterial culture (87.5%); however, SP was lower (76%, 100%, and 98%, respectively). Cytology had the best overall predictive values and accuracy for diagnosing septic peritonitis (PPV 100%, NPV 97.9%, and accuracy 98%) compared to RIA and bacterial culture.

CONCLUSIONS

RIA testing was similarly sensitive in identifying septic peritonitis compared to cytology and bacterial culture but was not very specific or accurate. As a stand-alone test, RIA commonly had false-positive test results, making it unreliable in identifying septic peritonitis. Cytology was the most accurate diagnostic test and had no false-positive results. Further investigation with a larger sample size and prevalence of septic peritonitis may prove beneficial.

Evaluation of short-term risk factors associated with dehiscence and death following full-thickness incisions of the large intestine in cats: 84 cases (1993-2015)

OBJECTIVE

To evaluate short-term risk factors associated with dehiscence and death in cats undergoing full-thickness large intestinal incisions.

ANIMALS

84 client-owned cats that had undergone full-thickness large intestinal incisions and for which information regarding outcome through postoperative day 7 was available.

PROCEDURES

Medical records from 4 veterinary teaching hospitals were reviewed. For cats that met the inclusion criteria, signalment, history, laboratory test results, surgical and medical procedures, perioperative complications, and outcome were analyzed. A Fisher exact or Wilcoxon rank sum test was used to identify individual variables associated with dehiscence of intestinal incisions or patient nonsurvival to hospital discharge or both.

RESULTS

84 cats met the inclusion criteria. The overall dehiscence and survival to hospital discharge rates were 8.3% (7/84 cats) and 94% (79/84 cats), respectively. Factors associated with dehiscence and nonsurvival to hospital discharge included presence of band neutrophils, performance of partial colectomy with colonic resection and anastomosis, administration of blood products, postoperative cardiopulmonary arrest, and incisional inflammation or infection. Factors associated with nonsurvival to hospital discharge only included low serum globulin concentration, repair of colonic trauma or dehiscence, and postoperative colonic dehiscence. Factors associated with dehiscence only included hypoalbuminemia, renal dysfunction, administration of blood products or > 2 classes of antimicrobials, and intra-abdominal fecal contamination.

CONCLUSIONS AND CLINICAL RELEVANCE

Results indicated that intestinal dehiscence and mortality rates associated with large intestinal incisions in cats may be higher than previously proposed, although the risk of either outcome was still low. Factors suggestive of systemic illness were associated with colonic dehiscence or death, and focused prospective studies of risk factors are warranted.

Evaluation of short-term outcomes and potential risk factors for death and intestinal dehiscence following full-thickness large intestinal incisions in dogs

OBJECTIVE

To determine complication rates for dogs in which full-thickness large intestinal incisions were performed, assess potential risk factors for death during hospitalization and for intestinal dehiscence following these surgeries, and report short-term mortality rates for these patients.

ANIMALS

90 dogs.

PROCEDURES

Medical records of 4 veterinary referral hospitals were reviewed to identify dogs that underwent large intestinal surgery requiring full-thickness incisions. Signalment, history, clinicopathologic data, medical treatments, surgical procedures, complications, and outcomes were recorded. Descriptive statistics were calculated; data were analyzed for association with survival to discharge (with logistic regression analysis) and postoperative intestinal dehiscence (with Fisher exact or Wilcoxon rank sum tests).

RESULTS

Overall 7-day postoperative intestinal dehiscence and mortality rates were 9 of 90 (10%) and 15 of 90 (17%). Dogs with preoperative anorexia, hypoglycemia, or neutrophils with toxic changes and those that received preoperative antimicrobial treatment had greater odds of death than did dogs without these findings. Preexisting colon trauma or dehiscence, preexisting peritonitis, administration of blood products, administration of > 2 classes of antimicrobials, positive microbial culture results for a surgical sample, and open abdominal management of peritonitis after surgery were associated with development of intestinal dehiscence. Five of 9 dogs with intestinal dehiscence died or were euthanized.

CONCLUSIONS AND CLINICAL RELEVANCE

Factors associated with failure to survive to discharge were considered suggestive of sepsis. Results suggested the dehiscence rate for full-thickness large intestinal incisions may not be as high as previously reported, but several factors may influence this outcome and larger, longer-term studies are needed to confirm these findings.

A Review of Normal Intestinal Healing, Intestinal Anastomosis, and the Pathophysiology and Treatment of Intestinal Dehiscence in Foreign Body Obstructions in Dogs

Small intestinal anastomoses are commonly performed in veterinary medicine following resection of diseased or devitalized intestinal tissue. Traditionally, suture has been employed to anastomose intestinal ends. However, use of intestinal staplers has become increasingly popular due to the ability to produce a rapid anastomosis with purported superior healing properties. Under normal conditions, intestinal healing occurs in three phases: inflammatory, proliferative, and maturation. Dehiscence, a devastating consequence of intestinal anastomosis surgery, most often occurs during the inflammatory phase of healing where the biomechanical strength of the anastomosis is almost entirely dependent on the anastomotic technique (suture or staple line). The resulting septic peritonitis is associated with a staggering morbidity rate upwards of 85% secondary to the severe systemic aberrations and financial burden induced by septic peritonitis and requirement of a second surgery, respectively. Intraoperative and postoperative consideration of the multifactorial nature of dehiscence is required for successful patient management to mitigate recurrence. Moreover, intensive postoperative critical care management is necessitated and includes antibiotic and fluid therapy, vasopressor or colloidal support, and monitoring of the patient's fluid balance and cardiovascular status. An understanding of anastomotic techniques and their relation to intestinal healing will facilitate intraoperative decision-making and may minimize the occurrence of postoperative dehiscence.

Adiponectin as a sepsis biomarker in dogs: Diagnostic and prognostic value

BACKGROUND

Adiponectin (ADPN) is an adipocytokine with insulin-sensitizing, vascular-protective, and anti-inflammatory properties for which concentration changes occur in response to inflammation. Little is known about the regulation of ADPN and the impact of this adipocytokine in septic dogs.

OBJECTIVE

We aimed to assess the diagnostic and prognostic value of ADPN vs other traditional acute-phase proteins (APPs), such as albumin (ALB), haptoglobin (HPT), fibrinogen (FBG), ferritin (FRT), and C-reactive protein (CRP) in dogs with naturally acquired sepsis.

METHODS

This prospective observational study included 20 dogs with sepsis, 27 with low-grade systemic inflammation (LGSI), and 18 clinically healthy dogs as controls. For method analyses, plasma samples were obtained from all dogs on admission and then every 24-48 hours until discharge or death in the septic group.

RESULTS

Septic dogs had lower ADPN (2.4 ± 0.46 vs 4.5 ± 0.41mg/L, P < .001) dand ALB (17 ± 1 vs 22 ± 0.8g/L, P = .002), and tended to have higher CRP (87 ± 4.8 vs 73 ± 4.1mg/L, P < .079) concentrations than dogs with LGSI on admission. Only ADPN and ALB were able to successfully discriminate animals with LGSI from those presenting with sepsis with areas under the curve (AUCs) for the receiver operating characteristic (ROC) curves of 0.811 and 0.789, respectively. In the septic group, ADPN concentration did not differ between survivors and non-survivors, either on admission or at discharge or death.

CONCLUSIONS

Although plasma ADPN can be used as a reliable negative APP in dogs with sepsis, further studies are warranted to confirm the usefulness of this biomarker in terms of disease progression and recovery.

Influence of a cell salvage washing system and leukocyte reduction filtration on bacterial contamination of canine whole blood ex vivo

OBJECTIVE

To determine the ability of cell salvage washing and leukoreduction filtration to remove bacterial contamination from canine whole blood.

STUDY DESIGN

Ex vivo nested cohort study.

SAMPLE POPULATION

Commercially purchased fresh canine whole blood (n = 33 units).

METHODS

Commercially obtained canine whole blood was inoculated with known concentrations of one of three species of bacteria, Escherichia coli (ATCC 25922), Staphylococcus pseudintermedius (quality control strain; Texas A&M University), or Pseudomonas aeruginosa (ATCC 27853). Negative controls were inoculated with sterile saline. The inoculated blood was processed through a cell salvage system and filtered through a series of two leukocyte reduction filters. Samples were aseptically collected at five points during processing (inoculum, prewash, postwash, post-first filtration, and post-second filtration) for bacterial enumeration.

RESULTS

Bacterial concentrations were reduced by 85.2%, 91.5%, and 93.9% for E coli, S pseudintermedius, and P aeruginosa, respectively, after washing (P < .0001), and bacterial concentrations were reduced by 99.9%, 100%, and 100%, respectively, after the first filtration (P < .0001). After the second filtration, none of the three species of bacteria could be isolated (100% reduction). No bacterial growth was obtained from negative controls throughout the study. The type of bacteria (P = .29) did not allow prediction of bacterial reduction.

CONCLUSION

Cell salvage washing combined with leukoreduction filtration eliminated bacterial contamination of whole dog blood (P < .0001).

CLINICAL SIGNIFICANCE

Cell salvage washing and leukoreduction filtration could be applied to intraoperative autotransfusion in clinical animals, especially those treated for trauma or hemorrhage with concurrent bacterial contamination.

Identification of risk factors for recurrent secondary septic peritonitis following initial surgical treatment of secondary septic peritonitis in dogs

OBJECTIVES

To report the incidence of and risk factors for development of recurrent secondary septic peritonitis (RSSP) in dogs. To report the outcome of dogs treated surgically for RSSP.

DESIGN

Retrospective study.

SETTING

University teaching hospital.

ANIMALS

One hundred forty-nine client-owned dogs treated surgically for secondary septic peritonitis (SSP).

INTERVENTIONS

None.

MEASUREMENTS AND RESULTS

The medical records database was searched for dogs that underwent surgery to treat SSP. Of 149 dogs that met the inclusion criteria, 15 (10.1%) dogs developed RSSP following surgery and 134 (89.9%) did not. Dogs with RSSP had significantly lower albumin prior to the first surgery to treat secondary septic peritonitis (SPsx1) (median 18 g/L [1.8 g/dL] vs 22 g/L [2.2 g/dL], P = 0.005) and significantly higher PCV prior to SPsx1 (median 52% vs 45%, P = 0.028). Dogs with septic peritonitis of gastrointestinal (GI) origin were significantly more likely to develop recurrent peritonitis than those with sepsis from a non-GI source (odds ratio [OR], 4.4, 95% CI: 0.95-20, P = 0.041). Of dogs with sepsis of GI origin, those with sepsis due to a foreign body were significantly more likely to develop RSSP than those with GI sepsis from a non-foreign body cause (OR, 7.2, 95% CI: 1.6-43, P = 0.0018). Of the 15 dogs in the RSSP group, 8 were euthanized without further treatment. Relaparotomy was performed in the remaining 7 cases; 3 of these (42.9%) survived.

CONCLUSIONS

There was a 10.1% rate of RSSP following SPsx1. Preoperative albumin was significantly lower and preoperative PCV was significantly higher in dogs that developed recurrence. Dogs with GI sepsis were at increased risk of recurrence and, among dogs with GI sepsis, the presence of a foreign body was an additional risk factor for recurrence.

The diagnostic and prognostic value of paraoxonase-1 and butyrylcholinesterase activities compared with acute-phase proteins in septic dogs and stratified by the acute patient physiologic and laboratory evaluation score

BACKGROUND

Sepsis is a complex syndrome that involves an increased oxidative stress status and dysregulation of cholinergic neurotransmission. Paraoxonase-1 (PON-1) and butyrylcholinesterase (BChE) activities have been identified as significant biomarkers to monitor such disorders in human septic patients.

OBJECTIVE

We aimed to determine the diagnostic and prognostic value of PON-1 and BChE vs other traditional acute-phase proteins such as albumin (ALB) and C-reactive protein (CRP) in septic dogs.

METHODS

This prospective observational study included 20 dogs with a diagnosis of sepsis, 27 with low-grade systemic inflammation (LGSI), and 10 healthy dogs that served as controls. Plasma samples were obtained from all dogs for analysis on admission, and then every 24-48 hours until discharge or death in the septic group.

RESULTS

Dogs with sepsis had lower PON-1 activity compared with dogs in the LGSI group (1.1 ± 0.10 vs 1.6 ± 0.08 U/mL, P = .002), but no differences in BChE activity were detected between the groups. PON-1, ALB, and CRP could successfully discriminate healthy animals from those with sepsis looking at the area under the curve (AUC) of the receiver operator characteristics curves (ROCs), which were 0.828, 0.903 and 1.000, respectively. Finally, although no differences were found among the groups for PON-1 or BChE activity, the nonsurvivor septic dogs had higher CRP (P = .002), lower ALB (P = .025) levels, and tended to have lower PON-1 (P = .082) activities than the survivors at patient death or discharge.

CONCLUSION

Septic dogs showed lower plasma PON-1 and higher BChE activities, but only PON-1 activity correlated with disease severity. Further studies are warranted to describe the usefulness of these new biomarkers of sepsis progression and recovery in dogs.

Prognostic indicators in cats with septic peritonitis (2002-2015): 83 cases

OBJECTIVE

To identify physical exam findings, clinicopathological parameters, time to surgery, empirical antimicrobial use, and culture results that could be associated with outcome in cats with septic peritonitis (SP).

DESIGN

Retrospective cohort study of cats from 2002 to 2015.

SETTING

Four university teaching hospitals.

ANIMALS

Eighty-three cats diagnosed with SP by cytology or culture.

INTERVENTIONS

None MEASUREMENTS AND MAIN RESULTS: Fifty-eight cats survived to discharge (69.9%); 1 cat was euthanized in surgery; 20 were euthanized postoperatively; 4 cats suffered cardiac arrest after surgery. The most common etiology of SP was secondary SP due to gastrointestinal perforation (49.4%), followed by primary SP (22.3%). Mean blood glucose concentration was significantly different between survivors and nonsurvivors (P = 0.006). Cats that received appropriate empirical antibiotic therapy were 4.4 times more likely to survive than cats that did not receive appropriate antibiotics (P = 0.018).

CONCLUSIONS

As previously documented, SP secondary to gastrointestinal leakage was the most common etiology. In this population, cats with a higher blood glucose concentration on presentation had a worse prognosis. Cats that received appropriate empirical antimicrobial therapy were more likely to survive.

Effect of peritoneal lavage on bacterial isolates in 40 dogs with confirmed septic peritonitis

OBJECTIVE

To evaluate bacterial isolates, antimicrobial drug susceptibility, and change in resistance among pre- and post-lavage culture samples in dogs with septic peritonitis.

DESIGN

Prospective observational study.

SETTING

Private practice referral hospital.

ANIMALS

Forty client-owned dogs with confirmed septic peritonitis requiring surgical intervention.

INTERVENTIONS

All dogs had perioperative abdominal lavage following source control with 200 to 300 mL/kg 0.9% sterile saline. Pre- and post-lavage aerobic and anaerobic culture samples were evaluated.

MEASUREMENTS AND MAIN RESULTS

Thirty-five of 40 dogs (87.5%) survived to hospital discharge. The likelihood of an aerobic organism to have multidrug resistance (resistance to 3 or more antimicrobial classes) post-lavage was a third of that pre-lavage (odds ratio [OR] 0.34, 95% CI [0.17-0.68], P = 0.01). Thirty-nine of 40 dogs (97.5%) received appropriate empiric antimicrobial therapy based on pre- and post-lavage culture results, of which 5 (12.8%) did not survive to discharge. The single dog with inappropriate antimicrobial therapy survived to discharge. The most frequent isolates detected included Escherichia coli, Clostridium perfringens, and Enterococcus faecalis. The same organism based on species was isolated in pre- and post-lavage cultures in 32 dogs, accounting for 59 anaerobic and aerobic isolates. There was a new bacterial isolate detected in 20 dogs, accounting for 46 isolates and an overall total decrease of 14 isolates between pre- and post-lavage culture (P = 0.09).

CONCLUSIONS

This study suggests that there is a significant decrease in the likelihood of isolating a multidrug resistant organism following peritoneal lavage, and aerobic and anaerobic culture results have the potential to change following peritoneal lavage, although this cannot be confirmed without further studies. Overall survival rates were higher than previously reported in the literature for septic peritonitis.

Acute mesenteric ischemia-like syndrome associated with suspected Spirocerca lupi aberrant migration in dogs

OBJECTIVE

To describe acute mesenteric infarction due to suspected Spirocerca lupi aberrant migration in 5 dogs.

CASE SERIES SUMMARY

All dogs were large breed, none of which exhibited typical clinical signs associated with spirocercosis. All dogs were eventually diagnosed with septic peritonitis. On exploratory laparotomy, thickening of the jejunal arteries, surrounding mesojejunum, and segmental necrosis were identified. Similar thickening and hematoma formation were found in other regions of the mesentery. In 4 of the cases, the necrotic segment was located in the distal jejunum. Histology revealed thrombotic mesenteric vessels with intralesional S. lupi nematode larvae. Resection and anastomosis of the necrosed section was performed and all but 1 dog survived and were discharged within 1-6 days.

NEW OR UNIQUE INFORMATION PROVIDED

Spirocerca lupi is a potential cause of mesenteric infarction in endemic areas when no other obvious etiology is identified.

Retrospective evaluation of 24 cases of gastrostomy tube usage in dogs with septic peritonitis (2009-2016)

OBJECTIVE

To describe the postoperative use of gastrostomy tubes (GT) in dogs with septic peritonitis. A secondary objective was to identify factors associated with GT placement and use that may be related to outcome.

DESIGN

Retrospective study.

SETTING

University teaching hospital.

ANIMALS

Twenty-four dogs diagnosed with septic peritonitis with GT placement at the time of exploratory laparotomy.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

Eighteen dogs (75%) survived to discharge. Eighteen dogs (75%) had a gastrointestinal source of septic peritonitis. Complications were reported in 12/24 (50%) patients. Four dogs (16.6%) had non-GT-related complications such as vomiting, regurgitation, or increased gastric residual volume. GT-related complications occurred in 8/24 (33.3%) dogs, the majority of which (6/8 [75%]) were minor and did not necessitate removal of the GT. Two dogs had major complications that required removal of the GT. Significant differences between survivors and nonsurvivors were found between the length of time after placement of the GT to when they began eating and outcome (discharge versus death versus euthanasia) (P = 0.03), and GT dwell time (length of time the GT was in place) and outcome (P = 0.006). Clinically relevant correlations were found between the time after placement of the GT until feeding and time after placement until voluntarily eating (P = 0.0349), time after placement of the GT until voluntarily eating and length of hospitalization (P = 0.0391), and time after placement of the GT until feeding and length of hospitalization (P = 0.036).

CONCLUSIONS

GTs can be placed during exploratory laparotomy in dogs with septic peritonitis. They facilitate early enteral nutrition and are associated with few clinically significant complications. Prospective studies are needed to determine the optimal postoperative feeding plan and the effects of early enteral nutrition on serum albumin concentration in this patient population.

Canine platelets express functional Toll-like receptor-4: lipopolysaccharide-triggered platelet activation is dependent on adenosine diphosphate and thromboxane A2 in dogs

BACKGROUND

Functional Toll-like receptor 4 (TLR4) has been characterized in human and murine platelets indicating that platelets play a role in inflammation and hemostasis during sepsis. It is unclear whether canine platelets could express functional TLR4 by responding to its ligand, lipopolysaccharide (LPS). We sought to determine if dogs express functional TLR4 and if LPS-induced platelet activation requires co-stimulation with ADP or thromboxane A₂ (TxA₂). Canine platelets were unstimulated (resting) or activated with thrombin or ADP prior to flow cytometric or microscopic analyses for TLR4 expression. We treated resting or ADP-primed platelets with LPS in the absence or presence of acetylsalicylic acid (ASA) and inhibited TLR4 with function blocking antibody or LPS from Rhodobacter sphaeroides (LPS-RS).

RESULTS

We discovered that dog platelets have variable TLR4 expression, which was upregulated following thrombin or ADP activation. LPS augmented P-selectin expression and thromboxane B₂ secretion in ADP-primed platelets via TLR4. Inhibition of cyclooxygenase by ASA attenuated LPS-mediated P-selectin expression demonstrating that TLR4 signaling in platelets is partially dependent on TxA₂ pathway.

CONCLUSION

Expression of functional TLR4 on canine platelets may contribute to hypercoagulability in clinical septic dogs. Cyclooxygenase and TxA₂ pathways in TLR4-mediated platelet activation may present novel therapeutic targets in dogs with sepsis.

Biomarker Guided Diagnosis of Septic Peritonitis in Dogs

Septic peritonitis (SP) is common in dogs and is associated with high mortality. Early recognition is essential to maximizing survival and may be aided by biomarker measurement. The present study aimed to evaluate the ability of biomarkers to discriminate septic peritonitis from non-septic ascites (NSA). Eighteen dogs with SP and 19 age-matched controls with NSA were enrolled. Contemporaneous blood and peritoneal effusion samples were obtained. Concentrations of cell-free DNA (cfDNA), cytokines, glucose, lactate, N-terminal pro-C-type natriuretic peptide (NT-proCNP), nucleosomes, and procalcitonin (PCT) were measured using commercial reagents and assays. Paired biomarker concentrations were compared with the Wilcoxon matched-pairs signed rank test, and biomarker concentrations between groups were compared with the Mann-Whitney U-test. P-values were adjusted for multiple comparisons using the Bonferroni correction. Receiver operating characteristic curves were generated to assess the ability of the above biomarkers to discriminate SP from NSA. Dogs with SP had significantly greater blood CCL2 concentrations than dogs with NSA (P = 0.032). Dogs with SP had significantly greater effusion CCL2, IL-6, IL-10, and lactate concentrations than dogs with NSA (P ≤ 0.0121). Blood-effusion concentration gradients of CCL2, glucose, IL-6, IL-10, and lactate were significantly different in dogs with SP compared to dogs with NSA (P ≤ 0.0165). Effusion lactate concentration had the highest AUROC value (0.866, 95% CI 0.751–0.980, P = 0.0001), although other biomarkers performed similarly. An effusion lactate concentration of 4.2 mmol/L was 72.2% (95% CI 46.5–90.3%) sensitive and 84.2% (95% CI 60.4–96.6%) specific for the diagnosis of SP.

Antibiotic use in critical illness

OBJECTIVE

To provide a review on the current use of antimicrobials with a discussion on the pharmacokinetic and pharmacodynamic profiles of antimicrobials in critically ill patients, the challenges of drug resistance, the use of diagnostic testing to direct therapy, and the selection of the most likely efficacious antimicrobial protocol.

ETIOLOGY

Patients in the intensive care unit often possess profound pathophysiologic changes that can complicate antimicrobial therapy. Although many antimicrobials have known pharmacodynamic profiles, critical illness can cause wide variations in their pharmacokinetics. The two principal factors affecting pharmacokinetics are volume of distribution and drug clearance. Understanding the interplay between critical illness, drug pharmacokinetics, and antimicrobial characteristics (ie, time-dependent vs concentration-dependent) may improve antimicrobial efficacy and patient outcome.

DIAGNOSIS

Utilizing bacterial culture and susceptibility can aid in identifying drug resistant infections, selecting the most appropriate antimicrobials, and hindering the future development of drug resistance.

THERAPY

Having a basic knowledge of antimicrobial function and how to use diagnostics to direct therapeutic treatment is paramount in managing this patient population. Diagnostic testing is not always available at the time of initiation of antimicrobial therapy, so empiric selections are often necessary. These empiric choices should be made based on the location of the infection and the most likely infecting bacteria.

PROGNOSIS

Studies have demonstrated the importance of moving away from a "one dose fits all" approach to antimicrobial therapy. Instead there has been a move toward an individualized approach that takes into consideration the pharmacokinetic and pharmacodynamic variabilities that can occur in critically ill patients.

Comparison of Initial and Postlavage Bacterial Culture Results of Septic Peritonitis in Dogs and Cats

Septic peritonitis is a common, life-threatening condition encountered in dogs and cats. Efficacy of peritoneal lavage has not been proven in veterinary studies. Our objective was to evaluate differences in bacterial identity and susceptibility in samples obtained pre- and postlavage in animals who underwent laparotomy for treatment of septic peritonitis and to assess the effect of empirical antimicrobial selection on survival. Culture samples were collected from the peritoneal surface pre- and postlavage from dogs and cats treated surgically for septic peritonitis. Culture results were compared for each patient with regard to bacterial isolates and bacterial susceptibility profiles. Survival to discharge was evaluated.

Microbial growth occurred in at least one culture in 88.6% of patients. There was no significant difference in bacterial isolates or susceptibility profiles pre- versus postlavage. Positive culture pre- or postlavage and appropriate antimicrobial selection did not significantly affect survival. For individual animals, culture results differed between pre- and postlavage samples, although no definitive effect of peritoneal lavage was seen for the population as a whole. Antimicrobials most commonly effective against isolates were Cefotaxime, Ceftazidime, and Imipenem. If prompt surgical source control is employed, antibiotic choice may not affect clinical outcome.

Lipopolysaccharide-induced neutrophil extracellular trap formation in canine neutrophils is dependent on histone H3 citrullination by peptidylarginine deiminase

Neutrophils release neutrophil extracellular traps (NETs), which are extracellular chromatin decorated with histones and antimicrobial proteins. Although known for antimicrobial properties, overzealous production of NETs (NETosis) may lead to cytotoxicity and multiple organ failure in sepsis. Pathogen-induced NETosis has been extensively studied in mice but its importance in dogs remains largely unknown. This study sought to characterize in vitro NETosis induced by E.coli LPS, including assessing the role of peptidylarginine deiminase (PAD) in canine NETosis. Neutrophils (1×10⁶ cells/ml) from healthy dogs were isolated and treated with 100μg/ml LPS, 100nM phorbol 12-myristate 13-acetate (PMA), or buffer for either 90 or 180min. NETs were assessed using fluorescence microscopy of living neutrophils and immunofluorescent microscopy. Supernatant and cellular debris were purified and cell-free DNA was quantified by spectrophotometry. The role of PAD was assessed by treating LPS- and PMA-activated neutrophils with 50, 100 or 200μM of the PAD inhibitor, Cl-amidine. In vitro NETosis was characterized by co-localization of cell-free DNA, citrullinated histone H3, and myeloperoxidase. LPS stimulation resulted in intracellular citrullination of histone H3. Compared to PMA chemically-induced NETosis, LPS resulted in smaller NETs with less extracellular citrullinated histone H3. Cl-amidine decreased citrullination of histones and NET production in either LPS- or PMA-stimulated neutrophils demonstrating that neutrophil PAD is essential for these cellular processes.

The role of antimicrobials in the treatment of sepsis and critical illness-related bacterial infections: examination of the evidence

OBJECTIVE

To appraise the evidence behind the Surviving Sepsis Campaign Guidelines on antimicrobial therapy in sepsis and evaluate relevant literature in small animal veterinary critical care.

DATA SOURCE

Electronic searches using MEDLINE and EMBASE databases.

HUMAN DATA SYNTHESIS

Current recommendations are to administer appropriate antimicrobials within 1 hour of a diagnosis of severe sepsis or septic shock. Evidence is supportive of this recommendation in septic shock but the evidence is less compelling in milder forms of critical illness-related infections. It is unclear when the administration of appropriate antimicrobials is most beneficial and when it should be considered essential. Evidence supports shorter courses of antimicrobial therapy for many infections seen in the critical care unit with the biomarkers procalcitonin and C-reactive protein helpful in guiding the duration of therapy.

VETERINARY DATA SYNTHESIS

Current evidence is lacking to support the use of early and aggressive use of antimicrobials in all patients with critical illness-related bacterial infections. Two studies failed to demonstrate improved survival in patients with pulmonary or abdominal infections administered appropriate vs inappropriate empirical antimicrobials. One study failed to show an improved survival when dogs with abdominal infections were administered antimicrobials within 1 hour vs 6 hours of diagnosis of infection. Information regarding ideal duration of antimicrobial therapy and use of biomarkers to guide therapy is currently lacking.

CONCLUSION

Clinicians should aim to administer early and appropriate antimicrobials; however, the impact this will have on patient outcome remains uncertain. The ability to administer early and appropriate antimicrobials may be considered a measure of the quality of medical practice rather than a prognostic indicator.