Risk factors for surgical site infection associated with clean surgical procedures in dogs

Mechanobiology of bacterial biofilms: Implications for orthopedic infection

Postoperative bacterial infections are prevalent complications in both human and veterinary orthopedic surgery, particularly when a biofilm develops. These infections often result in delayed healing, early revision, permanent functional loss, and, in severe cases, amputation. The diagnosis and treatment pose significant challenges, and bacterial biofilm further amplifies the therapeutic difficulty as it confers protection against the host immune system and against antibiotics which are usually administered as a first-line therapeutic option. However, the inappropriate use of antibiotics has led to the emergence of numerous multidrug-resistant organisms, which largely compromise the already imperfect treatment efficiency. In this context, the study of bacterial biofilm formation allows to better target antibiotic use and to evaluate alternative therapeutic strategies. Exploration of the roles played by mechanical factors on biofilm development is of particular interest, especially because cartilage and bone tissues are reactive environments that are subjected to mechanical load. This review delves into the current landscape of biofilm mechanobiology, exploring the role of mechanical factors on biofilm development through a multiscale prism starting from bacterial microscopic scale to reach biofilm mesoscopic size and finally the macroscopic scale of the fracture site or bone-implant interface.

A Prospective, Blinded, Open-Label Clinical Trial to Assess the Ability of Fluorescent Light Energy to Enhance Wound Healing after Mastectomy in Female Dogs

Mammary gland tumors represent the most frequently diagnosed malignant neoplasm in intact female dogs, and surgical removal represents the current gold standard treatment. To promote wound healing and prevent possible bacterial contamination, perioperative antimicrobials are commonly used in clinical practice, even though there are no publications establishing guidelines for the use of such drugs in canine mastectomy. The aim of the present study was to evaluate the ameliorative effect of fluorescent light energy on the quality of the healing process after mastectomy surgery in female dogs, in the absence of perioperative antimicrobial administration. Nine female dogs received a multiple-gland mastectomy due to gland tumors and received FLE application immediately after surgery and then five days after. The surgical incisions were evaluated by a blind investigator over time using the Modified Hollander Cosmesis and Modified Draize Wound Healing Score systems. Statistical analysis revealed a significant ameliorative effect of FLE in the control of step-off borders, contour irregularities, and excessive distortion. In addition, erythema, edema, and serous discharge were lower for those wounds managed with FLE. These results underscore the advantageous impact of FLE on the healing of post-mastectomy wounds in female dogs, offering the dual benefits of reducing potential infection risks and lessening the home care burden for pet owners.

Antimicrobial prophylaxis in companion animal surgery: A scoping review for European Network for Optimization of Antimicrobial Therapy (ENOVAT) guidelines

Surgical antimicrobial prophylaxis (SAP) is widely used to reduce the risk of surgical site infections (SSI), but there is uncertainty as to what the proportion of SSI reduction is. Therefore, it is difficult for surgeons to properly weigh the costs, risks and benefits for individual patients when deciding on the use of SAP, making it challenging to promote antimicrobial stewardship in primary practice settings. The objective of this study was to map the veterinary evidence focused on assessing the effect of SAP on SSI development and in order to identify surgical procedures with some research evidence and possible knowledge gaps. In October 2021 and December 2022, Scopus, CAB Abstracts, Web of Science Core Collection, Embase and MEDLINE were systematically searched. Double blinded screening of records was performed to identify studies in companion animals that reported on the use of SAP and SSI rates. Comparative data were available from 34 out of 39123 records screened including: eight randomised controlled trials (RCT), 23 cohort studies (seven prospective and 16 retrospective) and three retrospective case series representing 12476 dogs and cats in total. Extracted data described peri- or post-operative SAP in nine, and 25 studies, respectively. In the eight RCTs evaluating SAP in companion animals, surgical procedure coverage was skewed towards orthopaedic stifle surgeries in referral settings and there was large variation in SAP protocols, SSI definitions and follow-up periods. More standardized data collection and agreement of SSI definitions is needed to build stronger evidence for optimized patient care.

Complications and influence of cutaneous closure technique on subdermal plexus flaps in 97 dogs (2006-2022)

OBJECTIVE

To determine the incidence and severity of complications for subdermal plexus flaps in dogs and compare the complications when using sutures or staples for cutaneous closure of subdermal plexus flaps.

STUDY DESIGN

Retrospective monocentric study.

SAMPLE POPULATION

Ninety-seven client-owned dogs.

METHODS

Dogs that underwent wound reconstruction using subdermal plexus flaps were retrospectively identified. Type of flap, cutaneous closure technique, complications and level of complication associated with their use were recorded. Follow-up was considered adequate if it was more than 10 days postoperatively or until a complication occurred.

RESULTS

Complications were seen in 52 dogs (53.6%), of which 13/18 (72.2%) of dogs had cutaneous closure with skin staples versus 39/79 (49.3%) with skin sutures. The location of the mass/wound on the head and use of an advancement flap was associated with lower incidence of complications (p < .001; p = .018 respectively). Location of the mass/wound on the proximal pelvic limb was associated with a low level of complications (p = .01) on univariable analysis only. On multivariable analysis, only an increased bodyweight was associated with an increased incidence of complications (p = .029).

CONCLUSIONS

Increased weight may be associated with an increased risk of complications with subdermal plexus flaps. No risk factor was found to be associated with the severity of complications.

CLINICAL SIGNIFICANCE

Overall incidence of complications for subdermal plexus flaps in dogs in this study was 53.6%. The number of dogs included in the study was not sufficient to assess if the skin closure technique affects the incidence of complications.

Evaluation of a client questionnaire at diagnosing surgical site infections in an active surveillance system

OBJECTIVE

To report sensitivity, specificity, predictive values and accuracy of a client questionnaire at diagnosing surgical site infections (SSIs) and describe the impact of active surveillance on SSI detection.

STUDY DESIGN

Prospective, cohort study.

ANIMALS

Dogs and cats undergoing soft tissue or orthopedic surgery over a 12-month period at a referral hospital.

METHODS

Clients were emailed a questionnaire 30 days postoperatively, or 90 days where an implant was used. Three algorithms were developed to diagnose SSIs using one or both of two criteria: (1) presence of any wound healing problems; (2) wound dehiscence or antibiotic prescription, and either purulent discharge or two or more clinical signs (redness, pain, heat, swelling, discharge). Algorithmic diagnoses were compared to gold standard diagnoses made by veterinarians.

RESULTS

Of 754 surgical procedures, 309 responses were completed with 173 corresponding gold standard diagnoses. The most accurate algorithm determined "SSI" or "No SSI" from 90.2% of responses with 95.5% (92.4-98.6) accuracy, 82.6% (77-88.3) sensitivity, 97.7% (95.5-100) specificity, 86.4% (81.2-91.5) positive predictive value, and 97% (94.5-99.6) negative predictive value. "No SSI" was diagnosed in responses not meeting criterion 1, and "SSI" in responses meeting criteria 1 and 2. "Inconclusive" responses, comprising 9.8% of responses, met criterion 1 but not 2. Overall SSI rate was 62/754 (8.2%) and 12/62 (19.4%) SSIs were detected by active surveillance only.

CONCLUSION

Use of this client questionnaire accurately diagnosed SSIs; active surveillance increased SSI detection.

CLINICAL SIGNIFICANCE

Surveillance of SSIs should be active and can be simplified by using a client questionnaire and algorithmic diagnoses, allowing automated distribution, data collection and analysis.

Retrospective comparison of modified percutaneous cystolithotomy (PCCLm) and traditional open cystotomy (OC) in dogs: 218 cases (2010-2019)

OBJECTIVE

To compare short- and long-term clinical variables between dogs undergoing a modified percutaneous cystolithotomy (PCCLm) and open cystotomy (OC) and evaluate for risk factors associated with complications and outcomes within the groups.

STUDY DESIGN

Retrospective study.

ANIMALS

A total of 218 dogs.

METHODS

Records were reviewed for dogs that underwent PCCLm or OC between January 2010 and December 2019. Signalment; history and diagnostic findings; procedural, anesthetic, and hospitalized care data; complications; urolith recurrence; and follow-up were recorded. Logistic regression analysis was used to evaluate effects of clinical variables on outcomes within PCCLm and OC groups and to identify significant categorical variables between PCCLm and OC groups. Two sample t-tests were used to identify significant numerical variables between PCCLm and OC groups.

RESULTS

A total of 60.1% (131/218) of dogs underwent the PCCLm procedure and 39.9% (87/218) of dogs underwent the OC procedure. Anesthesia time (p < .001) was significantly longer in the OC group. No significant difference in incomplete urolith removal was noted between groups. Although surgical site infection and inflammation rates were not significantly different between OC and PCCLm groups, incisional infections were significantly associated with complications occurring during PCCLm (p = .027). Significantly reduced postoperative lower urinary tract signs (p = .022) were noted in the PCCLm group.

CONCLUSION

The PCCLm may result in reduced lower urinary tract signs postoperatively compared to OC, but other clear advantages of the PCCLm were not identified in this study.

CLINICAL SIGNIFICANCE

PCCLm procedures are an effective alternative to OC for urolith removal in dogs.

Retrospective evaluation of surgical site infection after open splenectomies with and without perioperative prophylactic antibiotic coverage

OBJECTIVES

Perioperative prophylactic antibiotics (PPA) are widely used in veterinary medicine to prevent surgical site infections (SSI). Current guidelines advocate the use in clean procedures only if surgeries exceed 90 minutes, or in patients with an ASA score ≥3. Procedure specific recommendations are currently lacking. The following study aimed to analyze the protective effect of PPA in dogs undergoing open splenectomy.

METHODS

The electronic database of our institution was searched for dogs that underwent splenectomy between 10/2017 and 01/2023. Data collection included age at presentation, breed, weight, reason for splenectomy, diagnosis, ASA class, PPA regime, surgery time, anesthesia time, lowest blood oxygen concentration during anesthesia, lowest body temperature, and lowest blood pressure during surgery as well as duration of hospitalization. Dogs were included if a follow-up of 30 days after surgery was available, or if death occurred within this timeframe.

RESULTS

A total of 112 dogs were included. Of these, 46 dogs received PPA, and 66 did not. Most dogs were classified ASA 3 or higher (PPA 87%, non-PPA 80.3%). One SSI (1.5% SSI rate) occurred in the non-PPA group (overall SSI rate 0.9%). Due to the low SSI rate, statistical analysis of risk factors for SSI development was not possible.

CONCLUSION

The described infection rate of 1.5% without PPA indicates, that splenectomy does not qualify as high-risk surgery for SSI, even in patients with ASA class 3 or higher.

CLINICAL RELEVANCE

As splenectomies are frequently performed, the findings of the current study could have a major impact on the overall antimicrobial burden in routine veterinary practice.

Independent risk factor for surgical site infection after orthopedic surgery

No significant progress has been made in the study of orthopedic surgical site infection (SSI) after different orthopedic surgery, and the analysis and prevention of risk factors for orthopedic SSI urgently need to be solved. A total of 154 patients underwent orthopedic surgery from April 2018 to December 2020. General information such as gender, age, marriage, diagnosis, surgical site, and anesthesia method was recorded. Statistical methods included Pearson chi-square test, univariate and multivariate logistic regression analyses, and receiver operating characteristic (ROC) curves. Based on Pearson's chi-square test, sex (P = .005), age (P = .027), marriage (P = .000), diagnosis (P = .034), and surgical site (P = .000) were significantly associated with SSI after orthopedic surgery. However, in the multiple linear regression analysis, only the surgical site (P = .035) was significantly associated with SSI after orthopedic surgery. In terms of multivariate logistic regression level, surgical site (odds ratio [OR] = 1.568, P = .039) was significantly associated with SSI. ROC curves were constructed to determine the effect of the surgical site on SSI after different orthopedic surgery (area under the curve [AUC] = 0.577, 95% CI = 0.487-0.0.666). In summary, the surgical site is an independent risk factor for SSI after orthopedic surgery, and "trauma" is more likely to develop SSI than spine, arthrosis, and others.

Indocyanine-based near-infrared lymphography for real-time detection of lymphatics in a cat with multiple mast cell tumours

Case summary

An 11-year-old female domestic shorthair cat was presented with cutaneous mast cell tumours (MCTs) localised at the right temporal region, the left buccal region and on the third digit of the right thoracic limb. Staging was negative and locoregional lymph nodes appeared normal, based on clinical findings. During surgery, real-time indocyanine green (ICG)-based lymphography was performed to detect the cutaneous draining pattern of all the primary MCTs. ICG was injected intracutaneously in four quadrants around each tumour, and a clear lymphogram was visible shortly after injection. Using near-infrared lymphography (NIR-L) for guidance, all lymphadenectomies were performed in 12 mins or less, with a maximal incision length of 3.5 cm. The smallest resected node was 0.9 cm in diameter. All MCTs were classified as low-grade cutaneous MCT. All four ICG-positive lymph nodes were considered premetastatic or metastatic. The only ICG-negative resected node was also negative for tumour cells. No complications related to NIR-L were recorded.

Relevance and novel information

This is the first description of NIR-L in a cat with MCT. Application was straightforward and ICG enrichment only occurred in the metastatic nodes, suggesting correct identification of lymphatic draining patterns. Of note, as previously described in dogs, we did detect nodal metastasis, despite low-grade primary tumours. The clinical relevance should be evaluated in future studies.

Outcome of caudal superficial epigastric axial pattern flaps in dogs and cats: 70 cases (2007-2020)

OBJECTIVES

To describe the outcome and complications associated with the use of caudal superficial epigastric axial pattern flaps in dogs and cats.

MATERIAL AND METHODS

Multicentre retrospective review and descriptive study of clinical records of dogs and cats having undergone caudal superficial epigastric axial pattern flaps between 2007 and 2020. Data retrieved included signalment, aetiology of surgical defect, tumour type, presence/absence of clean surgical margins, presence/absence of post-operative wound infection, use of peri- and post-operative antibiotics, duration of anaesthesia, duration of surgery, presence and duration of hypothermia, presence and duration of hypotension, presence/absence of post-operative surgical drain and length of caudal superficial epigastric axial pattern flap. The incidence of complications and outcomes were documented.

RESULTS

Seventy cases met the inclusion criteria; 51 dogs and 19 cats. In dogs, 67% of cases developed complications (59% minor, 8% major) and 33% had uneventful wound healing. In cats, 53% of cases developed complications, (47% minor, 5% major) and 47% had uneventful wound healing. In dogs, the percentage of cases experiencing dehiscence, necrosis, seroma, oedema and post-operative infection was 31%, 29%, 26%, 26% and 16% respectively. In cats, this was 26%, 16%, 11%, 0% and 5% respectively. A good overall outcome was seen in 77% of dogs and 79% of cats. A poor overall outcome was seen in 4% of dogs and 0% of cats.

CLINICAL SIGNIFICANCE

Caudal superficial epigastric axial pattern flaps are traditionally thought more robust than other flaps, yet complication rates remain high, despite a high overall success rate.