Incisional infections associated with ventral midline celiotomy in horses

A single-centre retrospective study of surgical site infection following equine colic surgery (2013‒2021)

BACKGROUND

Surgical site infection (SSI) is a significant cause of postoperative morbidity following equine laparotomy. Therefore, if risk factors for SSI can be identified, morbidity may consequently be reduced. The objectives of this study were to determine the prevalence of SSI in horses undergoing exploratory laparotomy at a single hospital over an 8-year period (2013‒2021), investigate the risk factors associated with SSI and report on the bacterial isolates identified.

METHODS

The medical records of horses that had an exploratory laparotomy performed at the teaching hospital due to colic were retrospectively reviewed. SSI was defined as any purulent or serous discharge from the laparotomy incision for more than 24 hours duration during hospitalisation. Pre-, intra- and postoperative risk factors for SSI were identified using multivariable logistic regression analysis.

RESULTS

A total of 143 horses met the criteria for inclusion in the study, of which 38 developed an SSI (26.6%, 95% confidence interval: 19.5-34.6%). Multivariable analysis revealed that the application of a postoperative abdominal bandage was significantly associated with a decreased likelihood of SSI (odds ratio = 0.29, p = 0.026).

LIMITATIONS

As this was a retrospective study performed at a single hospital, the findings may have limited generalisability.

CONCLUSIONS

The application of a postoperative abdominal bandage is protective against SSI in horses following exploratory laparotomy for colic.

Evaluation of a stent dressing and abdominal bandage on surgical site infection following emergency equine laparotomy: A randomised controlled trial

BACKGROUND

Surgical site infection (SSI) is a frequent complication following emergency equine laparotomy, negatively impacting equine welfare, increasing treatment costs and presenting a hospital biosecurity risk.

OBJECTIVES

To determine if a sutured-on stent dressing for incisional protection during anaesthetic recovery reduced SSI following emergency laparotomy.

STUDY DESIGN

Randomised controlled trial.

METHODS

Eligible horses were randomised to a sutured-on stent (intervention) or textile dressing (control) as the primary component of a 3-layer abdominal bandage placed for anaesthetic recovery. Horses were followed up to 90 days postoperatively. Data were analysed according to intention-to-treat principles. Time to SSI (primary outcome) for each group was analysed using a Cox proportional hazard model. Secondary outcomes (SSI and pyrexia during hospitalisation, days hospitalisation and incisional hernia formation at 90 days) were analysed using Chi-squared tests and a univariable logistic regression model (categorical data) or by comparing means between groups (continuous data).

RESULTS

Of 352 eligible horses enrolled (167 intervention group, 185 control group), SSI developed in 101 (28.7%) at a mean of 9.7 days (SD 4.6 days). Rate of SSI was not significantly different between groups unadjusted (hazard ratio [HR] 0.83, 95% CI 0.56-1.23, p = 0.4) or adjusted for variables significantly associated with rate of SSI (HR 0.88, 95% CI 0.59-1.30, p = 0.5). There were no significant differences in secondary outcomes between intervention and control groups.

MAIN LIMITATIONS

Single-centre study evaluating incisional protection from a primary dressing under a secondary adhesive and tertiary fabric abdominal bandage for anaesthetic recovery.

CONCLUSIONS

Use of a sutured-on stent compared with a textile adhesive dressing as the primary layer of an abdominal bandage for anaesthetic recovery did not reduce the rate of SSI. Further RCT are warranted to investigate efficacy of other interventions on reduction of SSI following emergency laparotomy in horses.

Prospective randomised comparison of different antimicrobial protocols for the prevention of surgical site infections in horses undergoing emergency exploratory celiotomy

BACKGROUND

Surgical site infection (SSI) is an important complication following emergency celiotomy in the horse. Judicious antimicrobial use is important for the prevention of antimicrobial resistance and the limitation of antimicrobial-associated complications. Previous studies in horses have found no association between SSI and perioperative antimicrobial duration, but the ideal duration of antimicrobial administration in horses undergoing exploratory celiotomy remains unclear.

OBJECTIVE

To compare SSI and describe post-operative complications, survival, duration and cost of hospitalisation in horses receiving one of two antimicrobial protocols following clean or select clean-contaminated emergency exploratory celiotomy.

STUDY DESIGN

Prospective randomised clinical study.

METHODS

Adult horses undergoing clean or selected clean-contaminated emergency celiotomy at The University of Georgia Teaching Hospital (2013-2019) were prospectively enrolled and randomised to protocol A (pre- and intra-operative antimicrobials only, n = 39) or protocol B (antimicrobials continued for 72 h of post-operative administration, n = 37). Incisional closure and protection were standardised. The prevalence of SSI was compared between protocols for horses surviving beyond day five of hospitalisation and additional clinical outcomes were described.

RESULTS

Horses in protocol A had an increased prevalence of SSI during hospitalisation compared with protocol B (6/37 [16%] vs. 0/35 [0%]; p = 0.03). The difference was of borderline significance at 4 weeks post-operatively (7/32 [22%] vs. 1/31 [3%]; p = 0.05).

MAIN LIMITATIONS

Planned enrolment was not met, providing only enough data for a small study. Numbers were limited by inclusion criteria as well as difficulties regarding owner consent and surgeon-determined enrolment. In light of the low statistical power of the study, results should be used to direct further research, and caution must be taken in applying them to clinical practice.

CONCLUSIONS

The difference in hospitalised SSI between groups and the low prevalence of SSI, particularly in the 72-h post-operative group, supports the need for continued research to determine optimal antimicrobial duration and protocols to reduce SSI in horses undergoing exploratory celiotomy.

Ultrasonographic findings of fluid accumulation and hyperechogenic spots suggestive of surgical site infection following laparotomy for colic in horses

BACKGROUND

The aim of this study was to compare ultrasonographic findings of the ventral midline incision after exploratory laparotomy for colic in horses with and without surgical site infection (SSI).

METHODS

Ultrasonographic examination of the surgical wound was performed on postoperative day 5 (D5) and day 10 (D10) to assess the presence of fluid accumulation, suture sinus formation, hyperechogenic spots and fistulous path. Clinical evaluation of the wound was used to classify horses with and without SSI. The accuracy, sensitivity, specificity and positive and negative predictive values of the ultrasonographic findings were then calculated. Multivariable logistic regression analyses were performed with SSI as a dependent variable and age, sex, breed and ultrasonographic findings as independent variables after univariate and collinearity analyses.

RESULTS

Twenty-nine of the 84 horses examined had an SSI. Detection of fluid accumulation and hyperechogenic spots increased the odds for SSI at D5 (odds ratio [OR]: 4.99, 95% confidence interval [CI]: 1.53-16.33, p = 0.008; OR: 10.78, 95% CI: 1.75-26.59, p = 0.01, respectively) and D10 (OR: 11.51, 95% CI: 2.39-55.47, p = 0.002; OR: 12.34, 95% CI: 3.45-44.15, p < 0.001, respectively).

LIMITATION

Ultrasonographic images were taken only on the longitudinal section.

CONCLUSION

Ultrasonographic examination is helpful in evaluating the surgical incision after laparotomy, with the detection of fluid accumulation and hyperechogenic spots surrounding the sutures being strongly related to SSI.

Ex vivo evaluation of a novel suture loop method for equine intestinal biopsies

OBJECTIVE

To compare a novel suture loop method for intestinal biopsies (SLB) with a two-layer, hand-sutured biopsy (HSB) technique in equine small and large intestines.

STUDY DESIGN

Experimental, randomized, ex vivo study.

ANIMALS

Eight healthy adult horses.

METHODS

The duodenum, aboral jejunum, and ventral and dorsal large colon were harvested after euthanasia and divided into three sections each. The sections were randomized to SLB, HSB, or control (C, no biopsy) groups. Tissue samples were excised after placement of a suture loop formed by a 4S Roeder knot and oversewn with a Cushing pattern using barbed suture (SLB), or a simple continuous pattern oversewn with a Cushing pattern (HSB). Intraluminal diameter was assessed with contrast radiographs; bursting pressure and wall tension were determined using a solid-state sensor after instillation of fluid. Tissue samples were evaluated by a board-certified pathologist.

RESULTS

Tissue samples were full thickness with similar depth and quality (p > .3). Changes in intraluminal diameter did not differ between methods (p > .16). The bursting pressures were higher for controls than biopsied sections (p < .009) but were not different between biopsy methods (p = .998). Bursting wall tension was higher for controls (p < .02) and was similar for both biopsy methods (p = .852).

CONCLUSION

The SLB was equivalent to HSB in strength and effect on intraluminal diameter. The HSB samples were larger and more likely to contain mucosa/villi for histologic diagnosis.

CLINICAL SIGNIFICANCE

The SLB method can be adapted for laparoscopic surgery to obtain both small and large intestinal biopsies. Further investigation is needed before clinical use.

Retrospective evaluation of the effects of a single intraoperative dose of dexamethasone in horses undergoing exploratory laparotomy for small intestinal lesions (2008-2019): 240 cases

OBJECTIVE

To determine the effect of a single intraoperative dose of dexamethasone on the risk of postoperative reflux (POR) in horses undergoing small intestinal surgery and to investigate its association with incisional complications and short-term survival.

DESIGN

Retrospective cohort study over an 11-year period (2008-2019).

SETTING

UK-based private referral center.

ANIMALS

Two hundred and forty client-owned horses >6 months of age undergoing exploratory laparotomy for treatment of a small intestinal lesion.

INTERVENTIONS

Ninety-seven horses received a single intraoperative dose of dexamethasone (0.1 mg/kg, IV).

MEASUREMENTS AND MAIN RESULTS

Of 97 horses that received dexamethasone, 52 (53.6%) required small intestinal resection. Of 143 horses that did not receive dexamethasone, small intestinal resection was performed in 78 (54.5%). A total of 70 horses (29%) developed POR. There was no difference in the risk of POR between horses that received dexamethasone (25/97; 26%) and those that did not (45/143; 31%, P = 0.34). Risk factors associated with the development of POR included small intestinal resection (odds ratio [OR]: 4.55, 95% confidence interval [CI]: 2.27-9.11, P < 0.001), a PCV >40% 24 hours postoperatively (OR: 4.11, 95% CI: 2-8.45, P < 0.001), and a WBC count >10 × 109/L on admission (OR: 3.29, 95% CI: 1.47-7.41, P = 0.004). Dexamethasone was not associated with the odds of POR. Horses undergoing repeat laparotomy had a higher risk of incisional infection (OR: 8.07, 95% CI: 1.98-32.81, P = 0.004). Dexamethasone administration was not associated with incisional infection. The development of POR was negatively associated with short-term survival (OR: 0.07, 95% CI: 0.03-0.17, P ≤ 0.001). Dexamethasone administration was not retained in the final multivariable model for survival.

CONCLUSIONS

Intraoperative dexamethasone was not associated with the development of POR in this study population, nor did it have an effect on postoperative survival or incisional infection in horses undergoing surgical management of small intestinal disease.

Comparison of incisional bursting strength of a bidirectional absorbable knotless suture material versus a standard continuous absorbable suture material for closure of the equine linea alba

OBJECTIVE

To evaluate the use of bidirectional knotless barbed suture material for closure of the equine linea alba.

STUDY DESIGN

Laboratory study.

ANIMAL OR SAMPLE POPULATION

Adult light horse cadavers (n = 24).

METHODS

A 25 cm incision was made through the linea alba, and a 200 L polyurethane bladder was positioned within the abdomen. The linea alba was closed either using USP2/EP5 bidirectional polydioxanone barbed suture or USP2/EP5 standard polydioxanone suture in a simple continuous pattern. Closure time was recorded for each suture type. The bladder was air-insufflated at 40 L/min, and the pressure at body wall failure recorded. The length of suture used for wound closure and wound failure modes were recorded. Suture length, closure time, bursting pressure, and failure modes were compared using Welch-Aspin t-tests.

RESULTS

The incisional bursting pressure was comparable between the two groups (p > .05). Less suture material (p < .01) was required with the barbed suture than the standard suture. Closure time was less for the barbed suture than the standard suture (p < .01). Suture failure was the main failure mode in both groups (83% cases).

CONCLUSIONS

Closure of the equine linea alba using bidirectional barbed suture material reduced the amount of foreign material in the wound and decreased closure time without compromising incisional strength.

CLINICAL RELEVANCE

Bidirectional barbed suture material could be considered as an alternative to standard suture materials for closure of the equine line alba.

Colic Surgery: Recent Updates

The following article provides an overview of the last 5 years of research and innovation within the field of equine colic surgery, focusing on new techniques, new or recently described lesions, prevention of lesion recurrence or postoperative complications, and updates in prognoses. Early surgical intervention is an important factor in horse survival.

Abdominal Sonographic Evaluation: In the Field, at the Hospital, and After Surgery

Abdominal sonography is currently a routine procedure in the evaluation of colic in the horse. This imaging technique is used in both the assessment of the horse presented in the emergency setting with acute colic and the assessment of the horse presented for chronic or recurrent colic in the nonemergency setting. Sonography for colic evaluation is used by specialists in different disciplines and by general practitioners in the ambulatory and hospital settings. In this review, we will focus on indications and clinical interpretation of findings as well as recent developments in abdominal sonography.

A multicenter retrospective case-cohort study on the prevalence of incisional morbidities in late pregnant mares following exploratory celiotomy (2014-2019): 579 cases

OBJECTIVE

To report the prevalence and risk factors for incisional morbidities in late pregnant and nonpregnant/early pregnant control mares following colic surgery.

DESIGN

Multicenter, retrospective, cohort study from January 2014 to December 2019.

SETTING

Two university teaching hospitals and 1 private referral center.

ANIMALS

Five hundred and seventy-nine fillies and mares ≥2 years old that underwent celiotomy. Pregnant mares (n = 54) were >240 days in gestation from the last known breeding date and were compared to control females (n = 525) undergoing colic surgery.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

Morbidity rates were not different between mare groups with 56% of pregnant mares and 51% of control mares reporting at least 1 morbidity. Incisional swelling was the most common reported complication in both groups. Incisional swelling was associated with shorter hospital stays (odds ratio [OR], 0.18; P < 0.01), and drainage was associated with a longer hospital stay (OR, 1.27; P ≤ 0.01) and with use of an abdominal bandage (OR, 4.4; P < 0.01). Herniation was associated with hypercapnia under anesthesia (OR, 1.1; P = 0.048), previous abdominal surgery (OR, 8.3; P = 0.003), and with use of an abdominal bandage (OR, 56; P = 0.006). Body wall dehiscence was associated with longer hospital stay (OR, 1.2; P < 0.01). Nonsurvival was higher in pregnant mares (13%) compared to control mares (5%; P = 0.02).

CONCLUSIONS

The prevalence of incisional morbidities did not differ between pregnant and control mares undergoing colic surgery. Several factors were associated with incisional morbidities, including the duration of surgery and anesthesia, anesthetic variables, abdominal bandage use, previous ventral abdominal incision, and longer duration of hospitalization.

Comparison of the zip skin closure system with conventional suture for skin closure of ventral midline incisions in horses

OBJECTIVE

To compare the application and healing of the zip skin closure system (ZSCS) with sutured closure by use of a split-scar model of ventral midline incisions in horses in a prospective, randomized experimental study.

ANIMALS

8 adult horses.

PROCEDURES

All horses underwent an exploratory ventral midline celiotomy with a standardized 30-cm skin incision. Each horse was randomized to have either the cranial 15 cm closed with suture and caudal 15 cm with the ZSCS or vice versa (split-scar model). Skin closure time was recorded and compared. Photography and skin biopsies were taken preoperatively and 14 days postoperatively. Cosmetic appearance was assessed by use of a proposed equine celiotomy incision score. Healing at 14 days was assessed by histopathology.

RESULTS

Skin closure times were faster with the ZSCS compared to sutured incisions. At 14 days postoperatively, the cosmetic appearance (equine celiotomy incision scores) for ZSCS incisions were better than sutured closure and histologic healing scores were not different between methods of closure. Subcuticular sutures were associated with deep dermal inflammation and necrosis independent of epidermal closure methods.

CLINICAL RELEVANCE

While limitations to the utility of the ZSCS are recognized, the potential benefits of expedient closure, good cosmetic outcome, and satisfactory healing make this method viable for closure of linear wounds or incisions in horses.

Recovery after General Anaesthesia in Adult Horses: A Structured Summary of the Literature

Simple Summary

Recovery is the most dangerous phase of general anaesthesia in horses. Numerous publications have reported about this phase, but structured reviews that try to reduce the risk of bias of narrative reviews/expert opinions, focussing on the topic are missing. Therefore, the aim of the present article was to publish the first structured review as a summary of the literature focussing on the recovery phase after general anaesthesia in horses. The objective was to summarise the available literature, taking into account the scientific evidence of the individual studies. A structured approach was followed with two experts in the field independently deciding on article inclusion and its level of scientific evidence. A total number of 444 articles, sorted by topics and classified based on their levels of evidence, were finally included into the present summary. The most important findings were summarised and discussed. The present structured review can be used as a compilation of the publications that, to date, focus on the recovery phase after general anaesthesia in adult horses. This type of review tries to minimise the risk of bias inherent to narrative reviews/expert opinions.

Abstract

Recovery remains the most dangerous phase of general anaesthesia in horses. The objective of this publication was to perform a structured literature review including levels of evidence (LoE) of each study with the keywords “recovery anaesthesia horse”, entered at once, in the search browsers PubMed and Web of Science. The two authors independently evaluated each candidate article. A final list with 444 articles was obtained on 5 April 2021, classified as: 41 “narrative reviews/expert opinions”, 16 “retrospective outcome studies”, 5 “surveys”, 59 “premedication/sedation and induction drugs”, 27 “maintenance with inhalant agents”, 55 “maintenance with total intravenous anaesthesia (TIVA)”, 3 “TIVA versus inhalants”, 56 “maintenance with partial intravenous anaesthesia (PIVA)”, 27 “other drugs used during maintenance”, 18 “drugs before/during recovery”, 18 “recovery systems”, 21 “respiratory system in recovery”, 41 “other factors”, 51 “case series/reports” and 6 “systems to score recoveries”. Of them, 167 were LoE 1, 36 LoE 2, 33 LoE 3, 110 LoE 4, 90 LoE 5 and 8 could not be classified based on the available abstract. This review can be used as an up-to-date compilation of the literature about recovery after general anaesthesia in adult horses that tried to minimise the bias inherent to narrative reviews.

Complications associated with closure of the linea alba using a combination of interrupted vertical mattress and simple interrupted sutures in equine laparotomies

OBJECTIVES

(1) Evaluate the occurrence and variables associated with incisional morbidities (IMs) after ventral median laparotomy when using interrupted vertical mattress sutures (IVMS) and (2) determine the occurrence of abdominal bandage-associated complications in horses.

METHODS

Occurrence of IM and bandage-associated complications were determined after single laparotomies (SL group; n=546 horses) and repeat laparotomies (RL group: multiple laparotomies within four weeks; n=30 horses) in horses that survived ≥7 days postoperatively. Univariate analysis and multivariate logistic regression were performed to evaluate variables associated with IM.

RESULTS

The IM rate was 9.52 per cent in the SL group and 33.33 per cent in the RL group. The actual infection rate was 5.31 per cent in the SL group and 26.67 per cent in the RL group. Overall, long-term clinically relevant wound complications was 1.68 per cent. After multivariate analysis, increased anaesthesia duration was associated with IM and performing an enterotomy and postoperative intravenous lidocaine administration were associated with incisional infection in the SL group; no parameter remained significant in the RL group. Bandage-related complications were recorded in 2.95 per cent of the cases.

CONCLUSIONS

These results suggest that the use of IVMS for closure of the linea alba is another viable option for closure and that an abdominal bandage does not appear to cause significant complications.