Abstract
Objectives
The aim of this study was to determine the incidence of and risk factors for both gastrointestinal (GI) incisional dehiscence and mortality in a large cohort of cats undergoing GI surgery. We hypothesized that cats with preoperative septic peritonitis (PSP), systemic inflammatory response syndrome (SIRS) or sepsis would have higher GI dehiscence and mortality rates than unaffected cats.
Methods
A medical records search identified cats with surgically created, full-thickness incisions into their stomach, small intestines or large intestines. Preoperative data, including signalment, clinical signs, comorbidities, surgical history, current medications, presenting physical examination findings, complete blood counts and serum biochemistry values, were collected. It was determined whether or not cats had PSP, SIRS or sepsis at admission. Intraoperative data, final diagnosis and postoperative variables such as vital parameters, bloodwork and (if applicable) the development of GI dehiscence or mortality were noted. Postoperative follow-up of at least 10 days was obtained in survivors.
Results
In total, 126 cats were included. One cat developed GI dehiscence following complete resection of a jejunal adenocarcinoma. Twenty-three cats (18.2%) died within 10 days of surgery. Cats with PSP (P = 0.0462) or that developed hypothermia 25–72 h postoperatively (P = 0.0055) had higher odds of mortality in multivariate analysis. Cats with PSP had 6.7-times higher odds of mortality than cats not diagnosed with PSP.
Conclusions and relevance
In cats receiving GI surgery, the incidence of GI incisional dehiscence was <1%. Cats with PSP had a higher likelihood of mortality. SIRS was a common finding in cats with septic peritonitis, but was not associated with mortality. Postoperative mortality during the home recovery period might be significant in cats. Future studies evaluating postoperative mortality in cats should consider extending the research period beyond the date of discharge.
Keywords
Introduction
Current veterinary literature suggests the rate of small intestinal incisional dehiscence in cats is nearly zero, and dehiscence of the large intestine is not much higher. In retrospective studies combining cats and dogs undergoing gastrointestinal (GI) surgery, cats represent the minority of the study population, and the GI dehiscence rates in cats are consistently reported to be zero.1–4 The exception, a study evaluating full-thickness GI biopsies in both species, reported a 2.3% dehiscence rate for cats. 5 Cat-specific studies focusing on small intestinal surgery are small (29–70 cats), but also report zero postoperative GI dehiscence.6–9 Small retrospective studies (including 11–38 cats) focused on large intestinal surgery for megacolon report either zero intestinal dehiscence or only single cases.10–12
While risk factors for dehiscence and mortality after GI surgery are well described in humans and dogs, information is almost non-existent in cats. Dehiscence rates in dogs undergoing small intestinal surgery range from 3.4% to 14%.3,4,13–17 Risk factors reported to be associated with GI dehiscence in dogs include preoperative septic peritonitis (PSP), low preoperative serum albumin, American Society of Anesthesiologists (ASA) status classification ⩾3, intraoperative hypotension, the presence of an intestinal foreign body and location (large intestine).3,16–18 Although risk factors for small intestinal incisional dehiscence have not been identified in cats, in a recent report band neutrophilia, a neutrophilic left shift, hypoalbuminemia and intra-abdominal fecal contamination were significantly associated with colonic incisional dehiscence in cats. 19
Sepsis, defined as systemic inflammatory response syndrome (SIRS) resulting from infection by bacteria, viruses, protozoa, fungi or helminths, is a frequent finding in very ill cats. 20 In a population of cats with a broad variety of systemic diseases, SIRS was detected in 16.2%, and, of that group, 19% had sepsis. 21 The mortality rate for sepsis is high, ranging from 33% to 39%.20–22 Both SIRS and sepsis may be under-recognized causes of death in cats undergoing GI surgery.
The authors believe the information available to the clinician to predict GI incisional dehiscence and mortality in cats after GI surgery is insufficient. The goals of this study were to determine the incidence of intestinal dehiscence and mortality in a large cohort of cats undergoing GI surgery, and to identify risk factors for dehiscence and mortality. The authors hypothesized that cats with PSP, SIRS or sepsis would have higher GI dehiscence and mortality rates than unaffected cats.
Materials and methods
Medical records from the Virginia-Maryland College of Veterinary Medicine were retrospectively evaluated via a combination of keyword search and fee code search for cats that had GI surgery between March 2002 and March 2020. Cats were included if they had surgically created, full-thickness incisions into any portion of their stomach, small intestines or large intestines. The exclusion criteria were incomplete or absent surgery reports, inability to determine length of hospitalization, intra-operative death, surgery for placement of a feeding tube only or postoperative follow-up of less than 10 days for survivors. The postoperative follow-up minimum period of 10 days corresponded with the earliest time that cats were evaluated for external suture removal. If a cat had multiple GI surgeries, each surgery was considered an independent event.
Preoperative data collected included patient signalment, clinical signs (including number of days affected), comorbidities, prior surgical history, current medications and presenting physical examination findings (temperature, heart rate, respiratory rate, body weight, body condition score, normal or abnormal mentation, presence/absence of abdominal mass/distention/discomfort). Preoperative complete blood count (CBC) and serum biochemistry values, when available, were obtained.
PSP was defined as at least one of the following: a positive bacterial culture from peritoneal fluid, the presence of intracellular bacteria noted on peritoneal fluid cytology in combination with surgical findings of peritonitis (purulent peritoneal fluid, malodorous peritoneal fluid and serosal inflammation) or identification of a non-iatrogenic perforation of the GI tract during surgery.
Whether or not each cat had SIRS or sepsis at the time of admission was documented based on the available information. SIRS was defined as the presence of ⩾2 of four predetermined criteria, which included a rectal temperature ⩾103.5°F (39.7°C) or <100°F (37.8°C), a heart rate of ⩾225 beats/min (bpm) or <140 bpm, a respiratory rate of ⩾40 breaths per min, a white blood cell (WBC) count of ⩾19,500 WBCs/μl, <5000 WBCs/μl or a band neutrophil fraction of ⩾5%.20,21 Changes to the leucon and the presence of a band neutrophil fraction were treated as a single criteria if more than one were present. Sepsis was diagnosed if a cat met the criteria for SIRS and had evidence of a bacterial infection (a positive bacterial culture from the peritoneal cavity, a visceral location not expected to have a native bacterial population or a cleaned wound or if the cat was diagnosed with PSP). 22
Anesthetic variables assessed included the patient’s ASA status (assessed prior to anesthesia by a trained veterinary technician, anesthesia resident, or veterinary anesthesiologist), time of day of anesthesia (during or outside of business hours), duration of anesthesia, presence of hypoxia (oxygen saturation <95% on pulse oximetry while receiving oxygen support), and both the duration and presence of hypothermia and hypotension while under anesthesia. Hypothermia was defined as a body temperature <98°F (36.7°C); hypotension was defined as a mean arterial pressure <60 mmHg (as determined by either direct or indirect blood pressure techniques).
The following surgical data were collected: duration of surgery; number, location and type of GI incisions made (-otomy vs -ectomy); apposition of surgery site with suture vs surgical staples; concurrent surgical procedures performed; and surgical findings (presence or absence of signs of PSP).
Based on the surgical findings and histopathology, the clinical diagnoses for each cat were organized into the following categories: obstructive (non-linear) GI foreign body (GIFB); linear GI foreign body (LFB); focal neoplasia (single location in the GI tract without distant metastasis); diffuse neoplasia (diffuse distribution or multiple locations in the GI tract and/or distant metastasis); biliary disease; trauma; megacolon; and miscellaneous. Cats were included in multiple categories if multiple disease processes were present.
Postoperative data collected included first postoperative CBC and serum biochemistry values when available. Vital parameters (temperature, heart rate, respiratory rate, blood pressure, body weight), fluid therapy and medications received during hospitalization were noted within specific time intervals after surgery (0–24 h, 25–72 h, >73 h postoperatively). Whether or not a patient received a blood product transfusion during the visit, the number of days of enteral nutrition after surgery and duration of hospitalization were noted.
Postoperative GI incisional dehiscence was defined as intracellular bacteria within peritoneal fluid in a cat combined with clinical deterioration, or dehiscence appreciated during subsequent surgery or necropsy. Cause of death was documented for each cat that died within 10 days of surgery. Cats that were euthanized and that died natural deaths were included in the same non-survivors group. If euthanasia was performed, the reason for euthanasia was documented, including whether or not euthanasia was elected due to prognostic vs financial reasons. Follow-up information was obtained for each patient to at least 10 days postoperatively through direct physical examinations or contact with referring veterinarians and/or owners.
Statistical analysis
Risk factors for postoperative GI incisional dehiscence were not analyzed (only one cat developed dehiscence). Clinical variables were analyzed to identify risk factors for mortality (outcome). Normal probability plots showed that numerical variables were skewed. Accordingly, numerical variables were summarized as median (range), while categorical variables were summarized as count and percentage. Bivariable associations between risk factors and mortality were assessed using the Wilcoxon rank sum test (continuous variables) and Fisher’s exact test (categorical variables). Significant variables on bivariable analysis were included in a multivariable logistic regression model and subjected to a stepwise variable reduction algorithm (P value to enter and P value to leave were both set to 0.05). To further investigate the association between the clinical diagnosis groups, PSP and SIRS, bivariable associations between the diagnoses and SIRS were assessed using Fisher’s exact test. Statistical significance was set to alpha = 0.05. All analyses were performed using SAS version 9.4.
Results
In total, 132 cats were identified as potential study candidates; of those, six were excluded owing to lack of sufficient follow-up. One hundred twenty-six cats met the inclusion criteria. Their age ranged from 1 to 19 years (median 9). Seventy-five cats were castrated males, one was an intact male, 49 were spayed females and one was an intact female. Breeds represented included domestic shorthair (n = 85), domestic longhair (n = 19) and six or less each of other breeds. Body weight ranged from 2 to 10.2 kg (median 4.4). Three cats had two surgeries each; the remainder had single surgical procedures.
Data were available at presentation to evaluate for SIRS in 103 cats. Of that group, 43 (41.7%) were identified as having SIRS (see Table S1 in the supplementary material). Within the SIRS-positive group, 21 (49%) cats had bacterial cultures performed; 11 (52.4%) of the cats with cultures were identified as having sepsis. PSP was diagnosed in 17 (13.5%) cats in the total population.
Cats were organized into clinical diagnoses. The most frequent indication for surgery was miscellaneous (n = 32 [25.4%]), followed by biliary disease (n = 24 [19%]), GIFB (n = 22 [17.5%]), diffuse neoplasia (n = 16 [12.7%]), focal neoplasia (n = 15 [11.9%]), megacolon (n = 14 [11.1%]), LFB (n = 7 [5.5%]) and trauma (n = 2 [1.6%]). Six (4.8%) cats were included in two categories simultaneously. Of the cats included in two categories simultaneously, two had both miscellaneous disease and diffuse neoplasia (1.6%), two had biliary disease and diffuse neoplasia (1.6%), one had biliary disease and focal neoplasia (0.8%) and one had miscellaneous disease and GIFB (0.8%).
Surgical findings and histopathology results varied. For cats with miscellaneous diagnoses, gross findings included iatrogenic duodenal perforation during endoscopy (n = 2), iatrogenic gastric perforation during endoscopy (n = 1), leakage of gastric contents at a percutaneous endoscopically placed gastrostomy tube site (n = 1), gastric stasis (n = 1) and pyloric stenosis (n = 1). The most frequent histopathologic finding was enteritis or colitis (n = 12), followed by no clinically significant findings (n = 5), feline infectious peritonitis (n = 3), duodenal ulceration (n = 2), duodenal polyp (n = 1), transmural jejunal necrosis (n = 1), colonic diverticulum with impaction (n = 1) and granulomatous peritonitis (n = 1). For cats with a diagnosis of feline infectious peritonitis, surgical intervention was performed to obtain GI biopsies.
Within the biliary surgery group, gross findings included iatrogenic bile duct ligation (n = 1) and extrahepatic biliary obstruction (n = 1). Suppurative cholangiohepatitis (n = 11) was the most frequent histopathologic diagnosis, followed by single cases of suppurative cholecystitis, suppurative cholecystitis with choledocholith formation, ulcerative cholecystitis, lymphoplasmacytic cholangiohepatitis and cholecystitis, lymphoplasmacytic cholangiohepatitis with hepatic cholangiocarcinoma and congenital hepatic fibrosis, biliary adenocarcinoma not directly involving the intestines and hemorrhagic cholecystitis. Three cats had neoplastic disease of the intestine causing focal biliary obstruction.
Within the diffuse neoplasia group, the most frequent histopathologic finding was small cell lymphoma (n = 10), followed by large cell lymphoma (n = 2), undifferentiated lymphoma (n = 2), adenocarcinoma (n = 2), histiocytic lymphoma (n = 1), undifferentiated sarcoma (n = 1) and granular round cell sarcoma (n = 1). Within the focal neoplasia group, undifferentiated lymphoma predominated (n = 4), followed by small cell lymphoma (n = 2), adenocarcinoma (n = 2) and one each of epitheliotropic lymphoma, leiomyoma, leiomyosarcoma, mast cell tumor and poorly differentiated spindle cell tumor.
Gastrointestinal incision locations included the stomach (n = 37 [29.4%]), small intestine (n = 109 [86.5%]) and large intestine (n = 30 [23.8%]). The number of incisions ranged from one to seven (median 1). Of the procedures, 88 were -otomies and 46 were -ectomies. Eight (6.3%) cats had -otomies and -ectomies performed simultaneously. Twenty-six (20.6%) cats had feeding tubes (gastrostomy or esophagostomy tubes) placed at the time of surgery in addition to another GI incision. Biliary surgery types included duodenotomy (n = 15), cholecystoduodenostomy (n = eight) and choledochoduodenostomy (n = 2). Seven cats had concurrent cholecystectomies.
One cat (0.8%) developed postoperative intestinal incisional dehiscence. This cat, who did not have PSP, had a jejunal adenocarcinoma completely resected and was euthanized owing to clinical deterioration 3 days postoperatively after intracellular bacteria were identified within its peritoneal effusion.
Twenty-three (18.2%) cats died or were euthanized within 10 days of surgery. Of those, nine died spontaneously and 14 were euthanized. Date of death ranged from the day of surgery to 9 days (median 3) postoperatively. Eighteen cats died while hospitalized and five died following hospital discharge. Reasons for death or euthanasia included owner wishes after receiving histopathology results (n = 4), persistent hypoxia following extubation (n = 3), cardiopulmonary arrest (n = 3), unresponsive hypotension (n = 2), lack of clinical improvement (n = 2), anemia unresponsive to transfusions (n = 1) and sudden death while hospitalized (n = 1). Of the cats that died of cardiopulmonary arrest, the cause of the arrest was not apparent for any cat. One cat was euthanized at the owner’s request while hospitalized when it simultaneously developed respiratory distress and hematochezia. There was no evidence of financial motivation for any euthanasia; patient prognosis was cited as the primary factor. Another cat died after hospitalization following the sudden onset of an inability to move its pelvic limbs. An additional cat presented to its primary medical practitioner febrile, with free abdominal fluid; an exploratory celiotomy revealed grossly purulent peritoneal fluid, abscessed jejunal lymph nodes and an intact enterotomy site. The cat died following attempted jejunal lymph node biopsy.
Statistically significant bivariable associations with mortality are reported in Tables 1 and 2. Bivariable associations that did not meet statistical significance are reported in Tables S2 and S3 in the supplementary material. SIRS and sepsis at the time of hospital admission were not found to be significant predictors of mortality (P = 0.3128 and P = 0.1486, respectively). Selected significant variables are further organized by disease category in Table 3 and Table S4 in the supplementary material.
Preoperative, intraoperative and postoperative significant bivariable associations between mortality within 10 days of surgery and numerical variables in cats undergoing gastrointestinal surgery
Cat mortality includes cats that were euthanized and cats that died as a result of underlying disease. P value significance set at >0.05
Concurrent surgical procedures not involving incisions into the gastrointestinal tract
Percentage of band neutrophils when compared with the total leukocyte count, on the first postoperative complete blood count
ALP = alkaline phosphatase; ASA = American Society of Anesthesiologists
Preoperative, intraoperative and postoperative bivariable associations between mortality within 10 days of surgery and categorical variables in cats undergoing gastrointestinal surgery
Data are n (%) unless otherwise stated. Cat mortality in this table includes cats that were euthanized and cats that died as a result of underlying disease. P value significance set at >0.05
Concurrent surgical procedures not involving incisions into the gastrointestinal tract
PSP = preoperative septic peritonitis; GIFB = gastrointestinal foreign body
Selected bivariable numerical variables for cats undergoing gastrointestinal surgery organized by disease category
Data are median (range), total
ALP = alkaline phosphatase; GIFB = gastrointestinal foreign body; LFB = linear gastrointestinal foreign body
Significant bivariable associations with mortality were further processed through multivariate analysis. Sixty-eight cats had all significant variables recorded and were included in the multivariate analysis. Two variables met statistical significance as predictors of non-survival during the multivariate analysis: PSP (P = 0.0462) and cats that were normothermic but developed hypothermia 25–72 h postoperatively (P = 0.0055). Cats with PSP had 6.7-times higher odds of mortality than cats that were not diagnosed with PSP (95% confidence interval [CI] 1.0–43.4). Cats that had hypothermia 25–72 h postoperatively had 35.3-times higher odds of mortality than cats that were euthermic or hyperthermic (95% CI 2.8–3.8). Cats that had hypothermia 25–72 h postoperatively had 35.3-times higher odds of mortality than cats that were euthermic or hyperthermic (CI 2.8–437.8).
The association between the clinical diagnosis groups, PSP and SIRS was investigated. Cats with LFB were less likely than cats with other diagnoses to fulfill the criteria for SIRS (P = 0.0201), with an incidence of 14.3%. Cats with PSP were more likely to fulfill the criteria for SIRS (P = 0.0390), with an incidence of 69.2%.
Discussion
In this population, the rate of dehiscence of GI incisions in cats was exceedingly low (0.8%) but not absent. Likewise, patient mortality was higher than expected at 18.2%. PSP was associated with decreased patient survival, but preoperative SIRS or sepsis were not.
GI incisional dehiscence in cats seems to be uncommon compared with other companion animal species. Previous studies evaluating GI dehiscence in cats have either focused on a single disease process, or were small groups.4,9 The increased diversity and larger population of cats in this report has reinforced previous literature findings that cats have low GI dehiscence rates. It is also possible that late GI dehiscence may have been more frequent in previous reports than was identified, but was not noted owing to the retrospective nature of the research.
The overall mortality rate in this population was higher than in previous reports of GI surgery in cats. This could be due to a common tendency to report patients’ postoperative survival as successful discharge from the hospital, rather than including the home recovery period. Interestingly, in this population, following the cats after discharge revealed inconsistent mortality timing among the clinical diagnosis groups. For example, the biliary surgery group was most likely to experience mortality within 1 day of surgery, whereas cats with neoplasia and miscellaneous diagnoses experienced the most mortality 5 days after surgery, one day after our median hospitalization time (of 4 days). This finding is consistent with a recent report describing mortality rates for surgical resection of large cell GI lymphoma in cats, where the in-hospital mortality rate was 10%, but an additional 12% of cats died following discharge. 23 While direct comparison of mortality between disease groups was not performed statistically in this population, the trends represented are worthy of further investigation with larger sample sizes. We suggest that observational clinical studies of cats that examine postoperative complications or mortality as an outcome should include the home recovery period in addition to hospitalization time.
Many variables identified as significant risk factors for mortality by bivariable analysis are explainable by concurrent confounding variables. Hypoproteinemia, total bilirubinemia, band neutrophilia, bradycardia and hypothermia have all been previously documented to be associated with septic peritonitis or severe sepsis.20,22,24–26 Therefore, it is reasonable to speculate that the increased patient mortality associated with each of these variables in this population could be due to related processes.
Elevated alkaline phosphatase (ALP) has not previously been associated with either septic peritonitis or sepsis in cats. Serum ALP has multiple sources in the cat, including the liver, intestines, kidney and bone. The elevated ALP concentrations in some study cats may be consistent with hepatobiliary disease; however, we did not find that cats with biliary disease had higher mortality rates than other groups. Several studies have documented the contributions of intestine ALP isoenzymes to serum ALP concentrations.27,28 Furthermore, cats with enteropathies have been shown to have elevated serum ALP. 29 It is possible that in some cats undergoing GI surgery, elevated ALP could be an indicator of enteropathy severity, which could predispose them to developing systemic disease or surgical complications.
It is interesting to note that cats with iatrogenic complications (such as GI perforation during endoscopy) did well clinically. This could be due to rapid identification of the complications at the time of the procedures and subsequent swift surgical treatment. All cats in this study that had GI perforations secondary to endoscopic procedures were surgically treated under the same anesthetic period. While the numbers of cats represented are small, the reported findings support rapid intervention to maximize the chances of a good clinical outcome if a GI perforation is suspected during a procedure.
Unlike objective variables, patient treatments and evaluations are based on clinicians’ subjective assessments, and are at risk of confirmation bias. This tendency may be the underlying cause of the associations between mortality and certain treatments, such as fluid therapy, blood transfusions and postoperative blood pressure monitoring. It is plausible that, if these treatments and monitoring were provided to all cats, the statistics for these variables would be altered.
The presence of PSP and the development of hypothermia more than a day after surgery were the only variables significantly associated with mortality in multivariate analysis. Septic peritonitis, which leads to systemic derangements in addition to local disease, has previously been documented to have high mortality in cats.26,30 Septic peritonitis is also a common underlying condition in cats with SIRS and sepsis.20,21,24 In this report, cats with septic peritonitis were more likely to have SIRS than cats without. However, despite its common presence in cats with septic peritonitis, preoperative SIRS was not associated with survival; this finding matched previous reports. 30
The overall prevalence of sepsis, an expected sequela of septic peritonitis, was low. Sepsis is notoriously difficult to identify in clinical patients, especially in a retrospective population. The diagnosis relies on the simultaneous presence of SIRS and either overt infectious disease (such as septic peritonitis) or confirmation of infection through positive bacterial cultures.20–22 The decision to take cultures of a surgical site is heavily clinician dependent. Additionally, bacterial cultures can be compromised by collection technique, concurrent antibiotic therapy, culture media selected, fastidious organisms and sample handing following collection.31–33 Hypothermia, such as was found in a subset of this study’s population, is a very common sequela of sepsis in cats, especially as they enter hypodynamic shock.20,22,24 Undiagnosed sepsis or other severe systemic disease could be responsible for the significantly increased mortality in cats that became hypothermic several days after surgery.
There were several important study limitations. As cats that died or were euthanized intraoperatively were excluded, this study cannot draw conclusions about intraoperative mortality. Not all clinicopathologic variables, especially postoperative variables, were available for each patient. As in any clinical study, reporting of an outcome measure depends on clinicians’ ability to diagnose and record it. Failure to recognize GI incisional dehiscence could underestimate the actual dehiscence rate. Sample size, while larger than previously published studies, is still relatively small compared with similar literature for humans; this limitation resulted in large CIs for the reported odds ratios. The long duration of the study period may mask changes to client perceptions of treatable disease, in addition to critical care advancements that could influence overall prognosis. The single location for data collection at a tertiary referral center may limit the generalizability of findings to study populations at other hospitals. Finally, as with all retrospective data, variables that are significantly correlated to mortality cannot be concluded to have a causal relationship.
Conclusions
In 126 cats receiving GI surgery, the incidence of GI incisional dehiscence was <1%. Cats with PSP had a higher likelihood of mortality. SIRS was common in cats with septic peritonitis, but not associated with mortality. Postoperative mortality during the home recovery period might be significant in cats. Future studies evaluating postoperative mortality in cats should consider extending the research period beyond the date of discharge.
Supplemental Material
Table S1
Distribution of variables evaluated for systemic inflammatory response syndrome at admission in 103 cats undergoing gastrointestinal surgery
Supplemental Material
Table S2
Preoperative, intraoperative and postoperative bivariable associations between mortality within 10 days of surgery and numerical variables that did not meet significance in cats undergoing gastrointestinal surgery
Supplemental Material
Table S3
Preoperative, intraoperative and postoperative bivariable associations between mortality within 10 days of surgery and categorical variables that did not meet significance in cats undergoing gastrointestinal surgery
Supplemental Material
Table S4
Selected bivariable categorical variables for cats undergoing gastrointestinal surgery organized by disease category
Footnotes
Acknowledgements
The authors would like to thank Stephen Werre BVM, MS, PhD for providing the statistics for this report.
Supplementary material
The following files are available online:
Table S1: Distribution of variables evaluated for systemic inflammatory response syndrome at admission in 103 cats undergoing gastrointestinal surgery.
Table S2: Preoperative, intraoperative and postoperative bivariable associations between mortality within 10 days of surgery and numerical variables that did not meet significance in cats undergoing gastrointestinal surgery.
Table S3: Preoperative, intraoperative and postoperative bivariable associations between mortality within 10 days of surgery and categorical variables that did not meet significance in cats undergoing gastrointestinal surgery.
Table S4: Selected bivariable categorical variables for cats undergoing gastrointestinal surgery organized by disease category.
Conflict of interest
The authors declare no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.
Funding
The authors received no financial support for the research, authorship, and/or publication of this article.
Ethical approval
This work involved the use of non-experimental animals only (including owned or unowned animals and data from prospective or retrospective studies). Established internationally recognized high standards (‘best practice’) of individual veterinary clinical patient care were followed. Ethical approval from a committee was therefore not specifically required for publication in JFMS.
Informed consent
Informed consent (either verbal or written) was obtained from the owner or legal guardian of all animal(s) described in this work (either experimental or non-experimental animals) for the procedure(s) undertaken (either prospective or retrospective studies). No animals or humans are identifiable in this publication, and therefore additional informed consent for publication was not required.
References
Supplementary Material
Please find the following supplemental material available below.
For Open Access articles published under a Creative Commons License, all supplemental material carries the same license as the article it is associated with.
For non-Open Access articles published, all supplemental material carries a non-exclusive license, and permission requests for re-use of supplemental material or any part of supplemental material shall be sent directly to the copyright owner as specified in the copyright notice associated with the article.
