Clinical relevance of positive intraoperative bacterial culture in tibial plateau leveling osteotomy in dogs: a retrospective study

BACKGROUND

Tibial plateau leveling osteotomy (TPLO) belongs to the most frequently used surgical method for the treatment of cranial cruciate ligament rupture in dogs. Surgical site infection (SSI) is one of the possible postoperative complications. The aim of this study was to evaluate the diagnostic value of intraoperative bacterial culture as a tool for the detection of intraoperative bacterial contamination progressing to infection development in canine TPLO. Electronic patient records from dogs who underwent TPLO between January 2018 to December 2020 were retrospectively reviewed. Intraoperative bacterial culture results, used antimicrobial drugs and presence of SSI were recorded.

RESULTS

Ninety-eight dogs were included in the study. SSI rate was 10.2%. All dogs who developed SSI (n = 10) had negative intraoperative bacterial cultures. None of the dogs with positive intraoperative bacterial culture (n = 6) developed SSI. The most cultured bacteria causing SSI was Staphylococcus pseudintermedius (n = 4).

CONCLUSIONS

Intraoperative bacterial culture in dogs undergoing TPLO is not suitable as a predictor of surgical site infection.

Germaine LL, Hoffmann DE, Sung J. A retrospective evaluation of the effect of oclacitinib (Apoquel) administration on development of surgical site infection following clean orthopedic stifle surgery

The aim of this study was to determine the effect of oclacitinib (Apoquel) on development of surgical site infections in canines following clean orthopedic stifle surgery. Medical records of dogs undergoing unilateral, clean orthopedic stifle procedures were retrospectively examined for development of post-operative surgical site infections. Data collected for statistical analysis included age, sex, body weight, current medications, anesthesia and surgery times, white blood cell count, and neutrophil count. Surgical site infections were identified in 8.7% (34/390) of stifle procedures- 8.0% (29/364) in dogs not treated with oclacitinib and 19.2% (5/26) in dogs treated with oclacitinib (p = 0.053). There was a significant difference in development of surgical site infection in dogs with longer anesthesia times (p = 0.003) and higher body weights (p = 0.037). Dogs being treated with oclacitinib at the time of clean, orthopedic stifle surgery did not have a significantly higher incidence of surgical site infections. However, client education regarding risk of infection and increased patient monitoring post-operatively are recommended, especially in patients with increased body weight or longer anesthetic times.

Indications for the removal of implants after fracture healing: A comparison between human and veterinary medicine

Indications for implant removal after fracture healing are still under debate in both human and veterinary medicine. Although hardware removal is a common procedure, it should not be undertaken lightly. Intra and post-operative complications are common and a thorough evaluation of the risks and benefits should be performed. This review aimed to collect and summarise published data on the indications for implant removal in small animals, compare the collected data with human and equine medicine, and investigate the existence of guidelines for this purpose. There is no international consensual agreement for implant removal after fracture healing, neither in small animals nor in human orthopaedics. Decision-making processes are still controversial in some scenarios, thus clear evidence-based protocols for implant removal are needed.

Fracture Healing in 37 Dogs and Cats with Implant Failure after Surgery (2013-2018)

Implant failure is common in small animal orthopedics, but risk factors are rarely reported. Our objective was to determine whether abnormal fracture healing was associated with implant failure after fracture fixation in dogs and cats in a consecutive series of cases. Thirty-seven client-owned animals (thirty-two dogs, five cats) diagnosed with implant failure after fracture treatment from January 2013-September 2018 were studied. Medical and radiographic records were retrospectively reviewed to identify patients that underwent fracture fixation using open reduction and internal fixation with subsequent radiographic evidence of implant failure. Area moment of inertia (AMI), plate working length, and bone screw density were determined. Implant failure was found in 39 fractures in 37 animals, representing 23% of fracture cases during the study period. Cases of implant failure were at increased risk of delayed union, malunion, or non-union (p < 0.0001). The most common cause of implant failure was loosening (54%); the second most common was plate failure that included low AMI locking plates (28%). Major complications found in 22/39 fractures (56%) were associated with delayed union (p < 0.01). Surgical revision was performed in 49% of implant failure cases. Complications were most frequently identified after treatment of humeral fractures (26%). We conclude mechanical failure of implants increases the risk for delayed or abnormal fracture healing and often requires revision surgery. Implant AMI should be considered during preoperative planning. Locking plates are associated with implant failure if plate bending stiffness is not sufficient, based on findings from this case series.

Surgical site infection after 769 Tibial Plateau Leveling Osteotomies

Objective

To report surgical site infections (SSI) after Tibial Plateau Leveling Osteotomy (TPLO), treatment course, associated risk factors, bacterial isolates and antimicrobial resistance.

Study design

Retrospective clinical cohort study.

Study population

Six hundred and twenty seven dogs and 769 TPLO procedures.

Methods

Data from electronic medical records of dogs undergoing TPLO between 2005 and 2015 at a single institution have been retrospectively reviewed. A generalized mixed logistic regression was used to determine possible risk factors. The Chi-Square test of independence was used to examine the relationship between the isolation of multidrug-resistant (MDR) bacteria and the development of major infections undergoing additional surgical treatment. To assess the correlation between number of SSI and number MDR isolate per year, Pearson's correlation coefficient was calculated.

Results

The overall complication rate was 19.3% (n = 149). SSI was most frequent with 8.5% (n = 65). Major SSI occurred in 6.8% (n = 52) TPLO (80.0% SSI). Staphylococcus (S.) pseudintermedius (n = 37) and S. aureus (n = 10) were most frequently isolated. Multidrug-resistant bacteria were identified in 2.7% (n = 21) TPLO (32.3% SSI) but were not associated with major SSI (p = 0.426). There was a strong positive correlation between number of MDR isolates per year and number of SSI per year [r ₍₉₎ = 0.79, p = 0.004]. Factors associated with SSI were previous TPLO in the contralateral stifle (p = 0.02, OR = 2.01, 95% CI = 1.11-3.64) and German Shepherd dogs (p = 0.035, OR = 4.41, 95% CI = 1.11-17.54). The use of non-locking implants was found to be protective (p = 0.02, OR = 0.179, 95% CI = 0.18-0.77).

Clinical significance

Infection with multidrug-resistant bacteria is an emerging problem in veterinary practice and treatment is challenging. The incidence of major SSI was found to be high but was not associated with the isolation of MDR bacteria.

Timing of and risk factors for deep surgical site infection requiring implant removal following canine tibial plateau leveling osteotomy

OBJECTIVE

To identify demographic risk factors for deep surgical site infection (SSI) requiring tibial plateau leveling osteotomy (TPLO) implant removal and time to implant removal.

ANIMALS

Four hundred and thirty-three dogs that underwent a TPLO (144 that developed a deep SSI and required implant removal, 289 that did not).

STUDY DESIGN

Retrospective case-control study.

METHODS

Records of dogs undergoing implant removal due to a deep SSI after TPLO between 2006 and 2018 at two referral centers were reviewed. These records were frequency-matched by date to dogs undergoing TPLO that did not require implant removal. Multivariable analyses tested associations between demographics and implant removal as well as timing of implant removal.

RESULTS

Deep SSI and implant removal occurred in 144 of 4813 (3.0%; 95% CI: 2.5, 3.5) dogs treated with TPLO. Implant removal was performed at a median of 279 days (range 49-2394 days) postoperatively. Male dogs (OR 1.8; 95% CI: 1.2, 2.7) and German Shepherd dogs (GSDs) (OR 7.4; 95% CI: 2.6, 20.5) were associated with plate removal. Earlier TPLO plate removal was associated with GSDs only (HR 2.4; 95% CI: 1.4, 4.1).

CONCLUSION

Implant removal due to SSI after TPLO was uncommon, although male dogs and GSDs seemed predisposed to this complication.

SIGNIFICANCE

These demographic risk factors can be used to educate owners regarding perioperative management.

Efficacy of postoperative antibiotic use after tibial plateau leveling osteotomy in dogs: A systematic review

OBJECTIVE

A systematic review of published data to determine whether postoperative antibiotic use after tibial plateau leveling osteotomy (TPLO) decreases infection rates.

STUDY DESIGN

Systematic review.

METHODS

A broad bibliographic search was performed in three online databases through March 2020 for publications on postoperative antibiotic use after TPLO in dogs. Search terms included dog, canine, TPLO, tibial plateau leveling osteotomy, infection, antibiotic, and antimicrobial. Articles that met inclusion criteria were evaluated for level of evidence (LoE) by a modified Oxford Level of Evidence (mOLE) and GRADE (Grading of Recommendations, Assessment, Development and Evaluation) classification and evaluation.

RESULTS

Thirteen studies met the inclusion criteria. Effect of antibiotic use was the primary question in four studies. Among those, 50% (2/4) were assigned a mOLE of 1b and a GRADE of moderate, while the other 50% (2/4) were assigned a mOLE of 4b or 4c with a GRADE of low. The two studies with the highest LoE did not provide evidence of the benefit of antibiotic usage. Results of only one study provided evidence to support the use of postoperative antibiotics. The remaining nine studies provided evaluation of antibiotic use secondarily and were all assigned a low LoE. Among these, 78% (7/9) provided evidence to support the use of postoperative antibiotics.

CONCLUSION

We found little evidence to support the use of postoperative antibiotics to reduce the risk of surgical site infections in dogs after TPLO. The answer to this clinical question is complicated by the lack of prospective studies and inconsistent treatment protocols in the evaluated studies.

CLINICAL SIGNIFICANCE

The clinical impact of postoperative antibiotic administration on infection rates after TPLO is uncertain.

Calcium sulfate antibiotic-impregnated bead implantation for deep surgical site infection associated with orthopedic surgery in small animals

OBJECTIVE

To report the outcomes and complications associated with antibiotic-impregnated calcium sulfate beads for prevention and treatment of orthopedic-related surgical site infection (SSI) in companion animals.

STUDY DESIGN

Retrospective case series.

ANIMALS

Client-owned cats (n = 2) and dogs (n = 14).

METHODS

Medical records of 16 cases in which implantation of antibiotic-impregnated calcium sulfate beads was performed for the prevention or treatment of SSI were reviewed. Information collected included signalment, prior surgery, reason for bead placement, antibiotics used, bacterial culture results, and clinical outcomes.

RESULTS

Surgical site infection resolved in six of 10 animals treated therapeutically and did not occur in six of six animals treated prophylactically. Susceptibility of the causative bacteria to the antibiotic implanted was confirmed in five of six cases with resolved SSI treated therapeutically but in only one of four cases with unresolved SSI treated therapeutically. Complications directly related to bead placement were evident in only one case in which beads extruded from external skeletal fixator pin tracts 7 days after implantation. At final follow-up, 11 of 12 animals without SSI had satisfactory limb use and no clinical, cytologic, or radiographic evidence of infection.

CONCLUSION

Implantation was well tolerated. Resolution of SSI was inconsistent; however, when bacteria were susceptible to the antibiotic implanted, SSI resolved in all but one case.

CLINICAL SIGNIFICANCE

Antibiotic-impregnated calcium sulfate beads could be considered for prevention or treatment of orthopedic SSI in small animals. A prospective clinical study is required to obtain additional information, including the value of preoperative bacterial culture.

Investigation of Variables Associated with Surgical Site Infection following the Management of Canine Cranial Cruciate Ligament Rupture with a Lateral Fabellotibial Suture

OBJECTIVE

 This study investigated variables associated with surgical site infection (SSI) in dogs with cranial cruciate ligament rupture managed with stifle joint examination and lateral fabellotibial suture stabilization.

STUDY DESIGN

 A retrospective study of dogs that had stifle arthroscopy, stifle arthrotomy, or a combination of both, followed by lateral fabellotibial suture stabilization for cranial cruciate ligament rupture. All cases had a minimum follow-up of 90 days. Lameness grades were recorded preoperatively, and at 6-week and final follow-up.

RESULTS

 One hundred fifty procedures in 130 dogs met the inclusion criteria. Overall, SSI rate was 17.3% and removal of the lateral fabellotibial suture was performed in 53% of SSI. Multivariable analysis showed significant association between SSI and bodyweight (p = 0.013), and induction using propofol (p = 0.029). Multilevel ordinal logistic regression analysis showed a greater proportion of dogs had a higher lameness grade at 6-week (p = 0.021) and final follow-up (p = 0.002) assessments in the infected compared with non-infected dogs.

CONCLUSION

 Our study demonstrated a higher SSI incidence than previously reported in dogs undergoing a lateral fabellotibial suture for cranial cruciate ligament rupture. Bodyweight and induction with propofol were identified as significant risk factors for postoperative SSI. Owners could be advised of an increased SSI risk in larger dogs and consideration should be given to selection of induction agent. Dogs that develop an SSI have a worse lameness grade at 6-week and final follow-up.

Subclinical bacteriuria and surgical site infections in dogs with cranial cruciate ligament disease

OBJECTIVE

To determine the prevalence of subclinical bacteriuria (SBU) in dogs with cranial cruciate ligament (CCL) disease, the clinical variables and clinicopathologic data associated with SBU, and the incidence of surgical site infections (SSI) in dogs with and without SBU.

STUDY DESIGN

Prospective, clinical cohort study.

ANIMALS

One hundred fifty-five dogs with CCL disease.

METHODS

Dogs had a urinalysis, sediment examination, and aerobic urine culture performed. Age, breed, sex, body weight, body condition score, clinical history, and physical examination findings were recorded. Dogs with SBU were not treated for bacteriuria or with postoperative antibiotics. Standard perioperative antimicrobials were provided for all dogs. Dogs that received nonsteroidal anti-inflammatory drugs were not excluded. Dogs that underwent an osteotomy were followed for at least 1 year to determine incidence of SSI. Outcomes and variables associated with SBU were assessed.

RESULTS

In 155 dogs with CCL disease, the prevalence of SBU was 6.5%, and SBU occurred exclusively in female dogs (11.4%). The incidence of SSI was 22.3% (25/112). Two of six dogs with SBU and 23/106 dogs without SBU developed SSI. Organisms isolated from SSI were different from those isolated from urine.

CONCLUSION

The prevalence of SBU in dogs with CCL disease was similar to that in other studies in which SBU was evaluated in various populations of dogs.

CLINICAL SIGNIFICANCE

Screening for and treatment of SBU may not be beneficial prior to tibial osteotomy for CCL disease. Additional studies are required to determine whether dogs with SBU have a greater risk of SSI.

Contributing factors to surgical site infection after tibial plateau leveling osteotomy: A follow-up retrospective study

OBJECTIVE

To identify factors associated with surgical site infection (SSI) after tibial plateau leveling osteotomy (TPLO).

STUDY DESIGN

Retrospective case series.

ANIMALS

Dogs (n = 541) that underwent TPLO (n = 659).

METHODS

Medical records of dogs that underwent TPLO from 2011-2018 were reviewed. Data collected included perioperative and postoperative antimicrobial administration, stifle inspection, duration of surgery and anesthesia, comorbidities, and development of SSI including timing, microbiological investigation, and implant removal. Referring veterinarians were contacted for all dogs without a recorded return visit. Risk factors for SSI were assessed by using a multivariable logistic regression model built by using a stepwise approach.

RESULTS

Surgical site infection was documented in 71 of 659 (11%) TPLO, with methicillin-resistant Staphylococcus pseudintermedius accounting for 20 of 71 (28%) infections. Protective factors against SSI included administration of postoperative antimicrobials (odds ratio [OR] 0.263; 95% CI = 0.157, 0.442) and timing of preoperative antimicrobial administration. Preoperative antimicrobial timing was protective against SSI when it was administered more than 60 minutes before the first incision compared with administration within 30 minutes (OR 0.275; 95% CI = 0.112, 0.676) or within 60 minutes (OR 0.419; 95% CI = 0.189, 0.929) of the first incision.

CONCLUSION

Early administration of perioperative antimicrobials and postoperative antimicrobial administration were protective against SSI after TPLO.

CLINICAL SIGNIFICANCE

Antimicrobials can influence the risk of SSI after TPLO. Perioperative and postoperative antimicrobial administration timing should be considered to reduce SSI.

In vitro elution of amikacin and Dispersin B from a polymer hydrogel

OBJECTIVE

To characterize the in vitro elution of amikacin and Dispersin B (β-N-acetylglucosaminidase) in a degradable hydrogel.

STUDY DESIGN

In vitro, prospective study.

METHODS

Amikacin (group A; 40 mg/mL), Dispersin B (group D; 70 μg/mL), or combined amikacin and Dispersin B (group AD; 40 mg/mL and 70 μg/mL, respectively) were added to a hydrogel. Ten aliquots per group were incubated in phosphate-buffered saline that was exchanged at 1, 4, 8, 12, and 24 hours and then once daily for 10 days. Eluted amikacin and Dispersin B were quantitated by using an amikacin reagent kit and a Dispersin B enzyme-linked immunosorbent assay kit, respectively. Time point drug concentrations were compared between groups by using repeated-measures analysis of variance, and total drug elution was compared by using an area under the curve calculation.

RESULTS

Amikacin alone, Dispersin B alone, and amikacin and Dispersin B combined together underwent rapid elution in the first 24 hours, followed by a gradual decrease over 10 days. The concentration of Dispersin B eluted in group D was higher at 1 day and lower from day 5 to day 10 compared with that in group AD. The concentration of amikacin eluted in group A was higher at 1, 4, and 8 hours and on day 10 and lower on day 1 compared with that in group AD. The total elution of amikacin was greater from group AD compared with that from group A (P = .02).

CONCLUSION

Combining amikacin and Dispersin B had an affect on the total elution of amikacin but not Dispersin B.

CLINICAL SIGNIFICANCE

The combination of amikacin and Dispersin B in a degradable hydrogel could allow local treatment of complex infections without the requirement for multiple invasive procedures.

Influence of administration of antimicrobial medications after tibial plateau leveling osteotomy on surgical site infections: A retrospective study of 308 dogs

OBJECTIVE

To determine the influence of prophylactic administration of oral antimicrobial medications after tibial plateau leveling osteotomy (TPLO) on surgical site infections (SSI) and antimicrobial-resistant infections.

STUDY DESIGN

Retrospective study.

SAMPLE POPULATION

Dogs treated with unilateral TPLO (n = 308) between January 2013 and December 2015.

METHODS

Medical records were reviewed for signalment, surgically treated limb, duration of surgery and anesthesia, postoperative administration of antimicrobial medications, antibiotic agent, surgeon, and development of SSI. Statistical analyses included descriptive statistics, simple linear regression, analysis of variance, Fisher's protected least significant difference, and χ² testing.

RESULTS

Data were collected from records of 31 dogs that did not receive antimicrobial medications and 277 dogs that did receive oral antimicrobial medications for 14 days after TPLO. Superficial incisional SSI was detected in two of 31 dogs that did not receive antimicrobial medications and in 48 of 277 dogs that did receive antimicrobial medications (P = .1194). Deep incisional SSI occurred in two of 31 dogs that did not receive antimicrobial medications and in 27 of 277 dogs that did receive antimicrobial medications (P = .5513). Antibiotic-resistant deep incisional SSI occurred in two of 31 dogs that did not receive antimicrobial medications and in 18 of 277 dogs that did receive antimicrobial medications (P = .9920). Body weight correlated with deep incisional SSI and resistant infections. Prolonged duration of surgery and anesthesia were associated with superficial incisional SSI, deep incisional SSI, and antibiotic resistance. Surgeons influenced deep incisional SSI.

CONCLUSION

Previously reported predisposing factors for infection were confirmed, but postoperative administration of antimicrobial medications was not protective against SSI nor did it predispose to antibiotic resistance in our clinical setting.

CLINICAL SIGNIFICANCE

This study does not provide evidence to support administration of prophylactic oral antimicrobial medications after unilateral TPLO.

Use of an amikacin-infused collagen sponge concurrent with implant removal for treatment of tibial plateau leveling osteotomy surgical site infection in 31 cases

OBJECTIVE

To report the use and long-term outcome of dogs with surgical site infection (SSI) after tibial plateau leveling osteotomy (TPO), treated with an amikacin-infused collagen sponge and implant removal.

STUDY DESIGN

Retrospective study.

ANIMALS

Thirty-one client-owned dogs.

METHODS

Medical records were reviewed for dogs with SSI after a TPLO that were treated with surgical implant removal and concurrent implantation of an amikacin-infused collagen sponge. Relevant clinical and surgical data were recorded. The TPLO implants were routinely removed; the surgical site was swabbed for culture. The sponge was aseptically infused with amikacin prior to implantation. Postprocedure examinations consisted of visual inspection of the incision by the surgeon and lameness scoring.

RESULTS

Thirty-one dogs met all inclusion criteria. Median follow-up time was 687 days. Short-term examination after implant removal and sponge implantation revealed uneventful incisional healing in 24 dogs. Six (19.4%) dogs exhibited inflamed incision sites a median of 4 days (range, 3-9) postoperatively that resolved without additional treatment. One (3.2%) dog required empirical antibiotic treatment 7 days postoperatively but was lost to long-term follow-up. Long-term follow-up examination revealed no clinical evidence of SSI recurrence and no lameness in the remaining 30 cases.

CONCLUSION

Surgical implant removal and implantation of an absorbable collagen sponge infused with amikacin alone was an effective treatment for postoperative TPLO SSI.

CLINICAL SIGNIFICANCE

This procedure had a 96.8% long-term resolution of SSI. It should be considered as a treatment option for TPLO SSI.

Impact of postoperative antibiotics on rates of infection and implant removal after tibial tuberosity advancement in 1,768 canine stifles

OBJECTIVE

To report infection rate, implant removal rate, and postoperative antibiotic therapy after tibial tuberosity advancement (TTA) in dogs.

STUDY DESIGN

Retrospective study.

ANIMALS

One thousand seven hundred sixty-eight stifles in 1,732 dogs.

METHODS

Medical records (January 2007-December 2011) of dogs treated with a TTA were reviewed. Cases were included if at least 1 year of postoperative follow-up was available and no additional procedures were performed on the stifle. Date of surgery, date of culture, culture and susceptibility results, postoperative antimicrobials used, and any implant removals were recorded. Use of postoperative antibiotics and implant removal were evaluated statistically for effect on infection occurrence and resolution.

RESULTS

Postoperative infections were diagnosed in 82 of 1,768 (4.6%) stifles. Implants were removed from 32 (39%) stifles, with plate and screw removal only in 23 (71.9%) stifles. The rate of infection did not differ between dogs with or without postoperative antibiotic therapy. However, dogs receiving postoperative antibiotic therapy were at risk for developing an oxacillin-resistant infection (P = .001). Oxacillin-resistant infections were associated with a requirement for implant removal to achieve resolution compared with other types of bacterial infections (P < .05).

CONCLUSION

No benefit was detected with the use of postoperative antibiotics after TTA in this population. Implant removal was infrequent, and the requirement for cage removal was not commonly required for infection resolution.

CLINICAL SIGNIFICANCE

This study does not provide evidence to support postoperative antibiotic therapy after TTA. Postoperative infection can be treated in most dogs without removal of the TTA cage.

Manual polishing of 3D printed metals produced by laser powder bed fusion reduces biofilm formation

Certain 3D printed metals and surface finishes may be better suited for canine patient specific orthopedic implants on the basis of minimizing potential bacterial biofilm growth. Thirty disks each of titanium alloy, stainless steel, and cobalt chromium alloy were 3D printed via laser powder bed fusion. Fifteen disks of each metal were subsequently polished. After incubation with a robust biofilm-forming methicillin-resistant Staphylococcus pseudintermedius isolate, disks were rinsed and sonicated to collect biofilm bacteria. Serial dilutions were plated on blood agar, and colony forming units were counted log (ln) transformed for analysis of variance. Interference microscopy quantified surface roughness for comparison to biofilm growth. Scanning electron microscopy on both pre- and post-sonicated disks confirmed biofilm presence and subsequent removal, and visualized surface features on cleaned disks. Significantly more bacteria grew on rough versus polished metal preparations (p < 0.0001). Titanium alloy had more bacterial biofilm growth compared to cobalt chromium alloy (p = 0.0001) and stainless steel (p < 0.0001). There were no significant growth differences between cobalt chromium alloy and stainless steel (p = 0.4737). Relationships between biofilm growth and surface roughness varied: positive with the rough preparations and negative with the smooth. Polished preparations had increased variance in surface roughness compared to rough preparations, and within disk variance predominated over between disk variance for all preparations with the exception of rough cobalt chromium alloy and rough stainless steel. Using scanning electron microscopy, bacterial biofilms tended to form in crevices. Overall, manual polishing of 3D printed surfaces significantly reduced biofilm growth, with preparation-specific relationships between surface roughness and biofilm growth. These results suggest that metallic implants produced by laser powder bed fusion should be polished. Further research will elucidate the optimal surface roughness per preparation to reduce potential biofilm formation and implant associated infection.

Protocol changes to reduce implant-associated infection rate after tibial plateau leveling osteotomy: 703 dogs, 811 TPLO (2006-2014)

OBJECTIVE

To determine the influence of a stricter aseptic protocol on implant-associated infection (IAI) rates after tibial plateau leveling osteotomy (TPLO).

STUDY DESIGN

Retrospective cohort study.

SAMPLE POPULATION

Seven hundred three dogs (811 TPLO).

METHODS

Medical records (2006-2014) of dogs with TPLO with a ≥18-month follow-up were reviewed. An established TPLO protocol was altered to include an iodophore-impregnated adhesive drape, cefazolin administration every 90 minutes intraoperatively and then every 4 hours until hospital discharge, orthopedic surgical gloves, triclosan-coated intradermal sutures (instead of staples), soft-padded bandage with mupirocin ointment, use of single-use gloves while handling treated dogs, and placement of an Elizabethan collar. Signalment, affected limb, protocol changes, IAI, time to explant, and culture and susceptibility results were recorded. Data were analyzed by using Fisher's exact test, Wilcoxon rank-sum test, and a multivariable logistic regression model.

RESULTS

TPLO plates were removed from 31 dogs (8.5% prechange, 1.3% postchange) because of a suspected IAI. Bacterial culture results from an explanted screw were positive in 26 dogs (7.4% prechange, 0.94% postchange). The odds ratio (OR) of IAI in the postchange cohort was decreased by 88% (OR 0.12, 95% CI 0.05-0.33) compared with the prechange cohort, after controlling for variables. Staphylococcus spp. were isolated from all implants removed from IAI-positive postchange dogs, 4/5 of which were methicillin resistant. No methicillin-resistant isolates were grown from the prechange cohort implants.

CONCLUSION

The protocol tested here decreased IAI rates after TPLO, but most infections diagnosed after its implementation involved methicillin-resistant isolates.

CLINICAL SIGNIFICANCE

The protocol reported here may be used as a guide in clinics seeking to reduce their IAI rates after TPLO. Postoperative infections after implementation of this protocol should be monitored to evaluate its potential impact on the emergence of antibiotic resistance.

A prospective, randomized, double-blinded, placebo-controlled clinical study on postoperative antibiotherapy in 150 arthroscopy-assisted tibial plateau leveling osteotomies in dogs

OBJECTIVE

To determine the influence of a 7-day course of postoperative antibiotherapy (cefpodoxime) on surgical site infections (SSI) after tibial plateau leveling osteotomy (TPLO).

STUDY DESIGN

Prospective, randomized, double-blinded, placebo-controlled clinical study.

SAMPLE POPULATION

One hundred fifty client-owned dogs, with consent.

METHODS

Dogs undergoing arthroscopy-assisted TPLO were randomly assigned to 1 of 2 groups, the placebo group receiving perioperative cefazolin and 7 days of placebo medication after surgery or the treatment group receiving perioperative cefazolin and 7 days of postoperative cefpodoxime. Twenty-seven factors were analyzed for association with SSI by using univariate analysis, Fisher's exact test, or Wilcoxon rank-sum test.

RESULTS

SSI rates did not differ (P = .34) between the placebo group (17%; 95% confidence level [CL] 7.94%-26.43%) and the treatment group (11% SSI; 95% CL 3.98%-18.88%). The probability that > 23% of dogs would benefit from postoperative antibiotherapy was less than 5%. The only association between the factors tested in this study and SSI involved the body weight (kg), with each 1 unit increase in kilogram weight increasing the odds of developing an SSI by 4.7%.

CONCLUSION

Although the wide CL may be consistent with a type II error, a 7-day course of cefpodoxime after arthroscopy-assisted TPLO did not influence postoperative SSI in the population tested here. In addition, only a small proportion of dogs would benefit from postoperative antibiotherapy under the conditions of our study.

CLINICAL SIGNIFICANCE

These results should prompt surgeons to reconsider systematic antibiotherapy after TPLO and justify additional studies to determine whether dogs predisposed to infection could benefit from such an approach.

Results and complications after removal of tibial tuberosity advancement cage for treatment of surgical site infections: A retrospective study

OBJECTIVE

To describe the surgical technique and report the short-term results after removal of tibial tuberosity advancement (TTA) cages in dogs with surgical site infections (SSI).

STUDY DESIGN

Retrospective clinical study.

ANIMALS

Seventeen client-owned dogs.

METHODS

Medical records of dogs treated for SSI by removal of a TTA cage between November 2012 and May 2015 were reviewed. Information collected included signalment, physical examination findings, affected stifle, cage size, date of SSI onset, time elapsed to implant removal, duration of procedure, culture results, any complications encountered, timing of follow-up recheck, and short-term results.

RESULTS

Seventeen dogs (20 stifles) were included. Clinical signs related to SSI started at a mean of 403 days after TTA, and implants were removed 474 days (mean) after TTA. No intraoperative complications were reported. Postoperative complications occurred in 40% of dogs. Three dogs developed major complications, including a tibial tuberosity fracture. Eighty-five percent of owners reported complete resolution of clinical signs related to the SSI and were satisfied with the outcome.

CONCLUSION

Surgical site infections were short- and long-term complications successfully treated by removal of the TTA cage in the majority of dogs in this study, although complications were common.

CLINICAL SIGNIFICANCE

Removal of the TTA cage can be considered as an adjunct to treat SSI but has the potential for postoperative complications.

Tibial plateau levelling osteotomy in 69 small breed dogs using conically coupled 1.9/2.5 mm locking plates

Objective: To report clinical experiences with the tibial plateau levelling osteotomy (TPLO) procedure in small breed dogs with cranial cruciate ligament (CCL) disease using specific, conically coupled, 1.9/2.5 mm locking plates and evaluating short-term complications and outcome.

Methods: Medical records of small breed dogs (<15 kg) that underwent TPLO using 1.9/2.5 mm locking plates were reviewed retrospectively. The preoperative, postoperative and six to eight weeks postoperative tibial plateau angle (TPA) measurements were determined from the radiographic images. Lameness evaluation was assessed subjectively preoperatively and six to eight weeks postoperatively.

Results: Sixty-nine small breed dogs (n = 79 stifles) were included in the study. Mean (± SD) preoperative TPA was 29.0 ± 3.4°, postoperative TPA was 5.8 ± 2.5°, and six to eight weeks postoperative TPA was 7.3 ± 4.1°. Sixteen complications occurred in 12 out of 79 TPLO procedures: three were intra-operative (intra-articular screw placement) and 13 were postoperative complications, of which nine were identified as minor complications not requiring surgical reintervention, and four as major complications requiring additional surgical intervention, including tibial tuberosity fracture (n = 1), osteomyelitis (n = 1), screw failure (n = 1), and plate breakage (n = 1). Lameness scores by clinical assessment reduced from a median value of 3/4 preoperatively to 1/4 at six to eight weeks postoperatively.

Clinical significance: 1.9/2.5 mm locking plates appear to be a valid choice of implant for the stabilization of unilateral TPLO in small breed dogs.

Bacterial recovery using sonication versus swabbing of titanium and stainless steel implants inoculated with Staphylococcus pseudintermedius or Pseudomonas aeruginosa

Objective: To evaluate the use of sonication to improve recovery of bacteria from metal discs infected with bacteria commonly associated with implant infections in veterinary medicine.

Methods: In vitro study in which sterile titanium (Ti6Al4V) and stainless steel (AIS1316-L) discs were incubated with either Staphylococcus pseudintermedius or Pseudomonas aeruginosa for 24 hours. The following three groups were compared: 1) the sonication group involved immersing the discs in sterile saline and sonicating for five minutes; 2) the sham group was considered a negative control in which the discs were immersed in saline for five minutes without sonication; and 3) the swab group involved systematically swabbing the implant with a sterile culturette. All samples were plated on blood agar and incubated for 24 hours. Colonies were then counted and compared.

Results: For both species of bacteria, there was a significant increase in bacterial colonies isolated using sonication compared to the other two study groups (p = 0.0001). No differences in bacterial growth were found between the two types of metal implants. There was a significant increase in bacterial colony counts for S. pseudintermedius when comparing the swab group versus the sham group, but this was not significant for P. aeruginosa.

Clinical significance: Sonication significantly improves recovery of bacteria commonly associated with veterinary implant-associated surgical site infections compared to swabbing of implants in vitro. A prospective clinical evaluation is indicated to determine the in vivo efficacy of sonication in veterinary patients.

Locking compression plate stabilization of 20 distal radial and ulnar fractures in toy and miniature breed dogs

Objective: To evaluate retrospectively the effectiveness of the Locking Compression Plate® (LCP), in the form of either a straight or notched head T-plate, for the treatment of fractures of the distal radius and ulna in a series of 20 toy and miniature breed dogs.

Methods: The medical records of toy and miniature breed dogs (<6 kg), greater than six months of age, with fractures of the distal radius and ulna from two veterinary hospitals were reviewed. The inclusion criteria included: fractures of the distal 1/3 of the radius and ulna and repair with open reduction and internal fixation utilizing an LCP (straight or notched head T-plate).

Results: Twenty fractures (20 dogs) satisfied the inclusion criteria; eight straight and 12 notched head T-plates were used, either 2.0 mm (n = 13) or 2.4 mm (n = 7). Hybrid fixation was performed in all dogs in one or both fragments. Mean time to radiographic union was 6.9 ± 2.5 weeks (range: 4–12 weeks) in 18/20 dogs with radiographic follow-up. One complication was observed: infection that resolved with antibiotic medication and implant removal. No other major complications occurred by the time of last follow-up. In all cases (mean follow-up: 15 ± 7 months), the reported limb function as evaluated by the referring veterinarian or owner was excellent.

Clinical significance: The LCP, used as a hybrid construct for the treatment of distal radial and ulnar fractures was shown to yield excellent clinical results with both uncomplicated healing and excellent functional outcomes in this series of toy and miniature breed dogs.

Taurolidine susceptibility of methicillin-resistant Staphylococcus pseudintermedius isolates

Infections caused by methicillin-resistant Staphylococcus pseudintermedius (MRSP) can be challenging to treat because they are often resistant to many other antimicrobial agents. We assessed the susceptibility of 29 MRSP isolates from dogs to taurolidine in vitro. There was no growth at 0.12% taurolidine and light growth at 0.06% for all isolates. Taurolidine was reliable at inhibiting growth of MRSP at a concentration of 1,200 µg/mL.

Perioperative risk factors for surgical site infection in tibial tuberosity advancement: 224 stifles

OBJECTIVE

To examine perioperative factors affecting surgical site infection (SSI) rate following tibial tuberosity advancement (TTA).

STUDY DESIGN

Retrospective case series.

SAMPLE POPULATION

224 stifles in 186 dogs.

METHODS

Medical records of dogs that underwent TTA in a single institution were reviewed. Information on signalment, anaesthetic and surgical parameters, as well as occurrence of SSI was recorded. Dogs were followed for a minimum of three months postoperatively. The association between perioperative factors and SSI was assessed using Chi-squared tests and binary logistic regression.

RESULTS

The prevalence of SSI was 5.3% (12/224 TTA). Surgical time (p = 0.02) and anaesthesia time (p = 0.03) were significantly associated with SSI. For every minute increase in surgical time and anaesthesia time, the likelihood of developing SSI increased by seven percent and four percent respectively. The use of postoperative antimicrobial therapy was not significantly associated with lower SSI (p = 0.719). Implants were removed in 1.3% of cases (3/224 TTA).

CONCLUSIONS

The findings of this study suggest that increased surgical and anaesthesia times are significant risk factors for SSI in TTA, and that there is no evidence that postoperative prophylactic antimicrobial therapy is associated with SSI rate.

Fighting surgical site infections in small animals: are we getting anywhere?

A diverse array of pathogen-related, patient-related, and caretaker-related issues influence risk and prevention of surgical site infections (SSIs). The entire surgical team involved in health care settings in which surgical procedures are performed play a pivotal role in the prevention of SSIs. In this article, current knowledge of SSI risk factors and prevention methods is reviewed. Although new avenues that can be explored in the prevention of SSIs in veterinary medicine are described, the main conclusion drawn is that the best method for prevention of SSI is to adhere to what we already know.

Prospective surgical site infection surveillance in dogs

OBJECTIVE

To 1) describe the incidence of surgical site infections (SSI) in dogs undergoing surgery at the Ontario Veterinary College Health Sciences Centre; 2) describe and compare procedure-specific SSI rates; and 3) identify factors associated with development of SSI.

STUDY DESIGN

Prospective, cohort study

ANIMALS

Dogs (n = 846) undergoing surgery during 45 weeks (September 2010-July 2011).

METHODS

Follow-up telephone conversation with dog owners was performed 30 days postoperatively, with additional 1-year follow-up performed for cases with surgical implants. A standardized questionnaire was administered to detect and characterize SSI.

RESULTS

SSI were identified in 26 (3.0%) dogs; 11 (42%) were classified as superficial SSI, whereas 13 were deep, and 2 were organ/space. Of the confirmed SSI, only 17 (65%) were documented in the medical records. Hypotension (P = .011), class of surgery (P = .029), and use of an implant (P = .001) increased the risk of SSI. Microbial cultures were submitted for 19 cases (73%) and of those, 74% were staphylococci.

CONCLUSIONS

SSI can result in devastating consequences in dogs and understanding risk factors is critical to target prevention practices. Whereas some risk factors such as hypotension are modifiable, others such as class of surgery are not. When possible, active surveillance should be used as part of a hospital infection control program.