Surgical retrieval of a guide wire lost during central venous catheterization in a dog

OBJECTIVE

To report a case of successful surgical removal of a guide wire lost during central venous catheterization.

CASE SUMMARY

A 28 kg, 4-year-old female neutered mixed breed dog presented to the primary care veterinarian with diabetic ketosis. During the process of central venous catheterization, the guide wire was accidently released and the entire length of the guide wire slipped into the jugular vein. Due to the absence of nearby interventional radiology facilities, surgical intervention was proposed. An ultrasound was used to determine that the guide wire was located in the caudal vena cava extending caudally into the right internal iliac vein. Rommel tourniquets were placed around the iliac vein cranial to the bifurcation of the common iliac vein into the external and internal iliac veins. A venotomy was performed in the right common iliac vein and the guide wire was grasped with hemostats and gently removed while alternately relaxing the cranial then caudal tourniquets. During anesthesia, ventricular premature contractions were noted that varied in frequency with the dog's positioning. Postoperative color flow Doppler ultrasound evaluation of the caudal vena cava, right common, internal and external iliac veins, and right femoral vein was normal with no evidence of thrombosis. Several days postoperative the dog's diabetic ketosis and ventricular premature contractions had resolved and color flow Doppler ultrasound evaluation was normal with no evidence of thrombosis.

NEW OR UNIQUE INFORMATION PROVIDED

To the authors' knowledge, this is the first reported veterinary case of loss and subsequent surgical retrieval of a central venous catheter guide wire.

The effects of multiple high-resolution peripheral quantitative computed tomography scans on bone healing in a rabbit radial bone defect model

The use of in vivo high-resolution computed tomography (CT) scanners provides the unique opportunity for evaluating temporal progression in healing of bone defects. However, these in vivo scanners impose ionizing radiation that could affect the healing and morphology of the bone. The primary objective of this study was to determine the effects of in vivo scanning at 2-week intervals on bone healing of a critical sized radial defect in rabbits and to investigate the effect of this radiation protocol on bone marrow cell viability using clinically applicable radiation doses. Thirty male rabbits were randomized into three groups: two groups received a 15 mm defect in the left radius that was filled with an autologous bone graft (DEF-CT and DEF-SHAM), and one group acted as an intact control (INT-CT). The duration of the study was 6 weeks. DEF-CT and INT-CT had high-resolution CT scans performed at 2-week intervals. The total cumulative radiation dose was 81.6 mGy per animal. DEF-SHAM received sham CT scans at the same time points. In group DEF-CT, the bone volume (BV) in the defect increased significantly over time (p≤0.002, for all comparisons); the bone mineral density (BMD) in the defect decreased over time and was significantly lower at weeks 4 and 6 than at weeks 0 and 2 (p<0.001, for all comparisons). In group INT-CT, BV and BMD did not change over time (p=1, for all comparison). The BV (p=0.50) and the BMD (p=0.37) in the defect as measured by microCT scan during ex vivo analysis was not significantly different between DEF-CT and DEF-SHAM. Similarly, histomorphometry showed no significant difference in the total bone area (p=0.22) and percentage bone within the defect (p=0.24) between these groups. Bone marrow analysis of the left (radiated) and right (non-radiated) radius of the INT-CT group via a Colony Forming Units (CFU) assay demonstrated an average of 25.3 and 28.5 colonies for radiated and non-radiated radii, respectively (p=0.72). In conclusion, there was no significant difference in bone healing between radiated and non-radiated radius defects in rabbits. This is an important finding as it demonstrates that serial in vivo high resolution-CT imaging can not only provide accurate tissue regeneration data, but it can also be used to reduce the number of temporal cohorts within an experimental design.

The use of Reamer Irrigator Aspirator (RIA) autograft harvest in the treatment of critical-sized iliac wing defects in sheep: investigation of dexamethasone and beta-tricalcium phosphate augmentation

Bone grafts are commonly used for the treatment of segmental bone defects and fracture non-unions. Recently, osseous particles obtained during intermedullary canal reaming (using a Reamer-Irrigator-Aspirator (RIA) device) have been evaluated as graft material during in vitro and clinical studies. The aim of this study was to evaluate and quantify new bone formation after implantation of bone graft material obtained after reaming of the tibia in a bilateral critical-sized iliac wing defect in sheep and to investigate the effect of the augmentation of this graft. A reamer bone graft alone, or after short term incubation in a dexamethasone enriched solution, and a reamer graft collected using beta-tricalcium phosphate (β-TCP) granules in the filter of the RIA collection device were compared to autologous iliac wing graft. In addition, reamer graft was combined with the cellular fraction collected from the irrigation fluid with and without short-term incubation in a dexamethasone enriched solution. It was hypothesized that the amount of physical bone in the reamer bone graft groups would be higher than the amount in the autologous iliac wing graft group and that augmentation of a reamer bone graft would increase bone formation. Three months after implantation, the amount of new bone formation (as percentage of the total defect volume) in the defects was evaluated ex-vivo by means of micro-CT and histomorphometry. The mean amount of bone in the autologous iliac wing graft group was 17.7% and 16.8% for micro-CT and histomorphometry, respectively. The mean amount of bone in all reamer graft groups ranged between 20.4-29.2% (micro-CT) and 17.0-25.4% (histomorphometry). Reamer graft collected using β-TCP granules (29.2±1.7%) in the filter produced a significantly higher amount of bone in comparison to an autologous iliac wing graft evaluated by micro-CT. RIA bone grafts added a small increase in bone volume to the 3month graft volume in this preclinical sheep model. The current model does not support the use of short-term high concentration dexamethasone for augmentation of a graft volume. If avoidance of an iliac wing graft is desirable, or a reaming procedure is required, then a RIA graft or RIA graft plus β-TCP granules are as good as the current gold standard for this model.

Minimally invasive abdominal and thoracic surgery: principles and instrumentation

Minimally invasive surgery, including laparoscopy, thoracoscopy, and endoscopic-assisted procedures, is becoming more common in veterinary medicine. The basic principles of laparoscopy and thoracoscopy involve gaining access to a cavity through small incisions, creating a workspace, and maneuvering extracorporeally activated instruments within that workspace.

Minimally invasive abdominal and thoracic surgery: techniques

Laparoscopy, thoracoscopy, and other endoscopic-assisted procedures have many uses in veterinary medicine. Diagnosis and biopsy are currently the most common uses of minimally invasive techniques, but popularity for procedures such as ovariectomy, cancer staging, lung lobectomy, and pericardectomy is rising. This article touches on basic surgical procedures and describes some more advanced techniques.

Finite element analysis of a novel pin-sleeve system for external fixation of distal limb fractures in horses

The transfixation pin cast (TPC) is an external skeletal fixation technique used to treat horses with distal limb fractures, but its use is often associated with pin-loosening and an increased risk of treatment failure. To address implant loosening, the pin sleeve cast system (PSC) was recently designed and consists of a pin-sleeve unit inserted into the bone. Each pin runs through a sleeve placed in the bone, making contact at two fixed points only within the sleeve. Each pin is attached to a ring embedded in a resin cast. In this report, the mechanical performance of a traditional TPC pin arrangement was compared with that of the PSC using validated finite element models of bone substitutes previously tested in vitro. The PSC resulted in a marked reduction in peak strain magnitude around the pins and a more even distribution of strain across the bone cortex. The two systems resulted in comparable proximal fragment displacement and had a similar stress concentration around bone defects during implant removal. The findings suggest that the PSC load transfer mechanism is effective even in geometrically complex structures like equine bones.

Hiatal Hernia in the Dog: A Clinical Report of Four Chinese Shar Peis

Four Chinese shar pei littermate puppies were presented for vomiting, regurgitation, hypersalivation, and poor growth. Diagnosis of hiatal hernia was made for each of the four dogs based on survey radiographs and barium esophagram studies. All dogs initially underwent medical therapy, to which only one dog responded. All dogs underwent surgical treatment, which included manual hernia reduction followed by phrenoplasty, esophagopexy, and left incisional gastropexy, 5 to 40 days following initiation of medical therapy. The three surgical techniques described eliminated the need to enter the pleural cavity and offered excellent long-term results with no recurrence of clinical signs following surgery.

In Vitro Mechanical Comparison of Screwed, Bolted, and Novel Interlocking Nail Systems to Buttress Plate Fixation in Torsion and Mediolateral Bending

OBJECTIVE

To compare standard interlocking nails (ILN) with a newly designed ILN featuring an angle-stable locking mechanism (ILNn).

STUDY DESIGN

Six experimental groups.

SAMPLE POPULATION

Bone models (n=48) treated with 6 and 8 mm nails locked with screws or bolts (ILN6s, ILN8s, ILN6b, ILN8b, respectively), ILNn, and a 3.5 mm broad-DCP (br-DCP); n=4/testing mode.

METHODS

Specimens were tested in torsion or 4-point bending. Construct compliance, deformation, and slack were statistically compared (P<.05).

RESULTS

Regardless of testing mode, construct compliance was greater with smaller ILN. Screwed constructs were more compliant than bolted ones, with a significant difference between ILN6s and ILN6b in torsion. Plated constructs were significantly more compliant than the ILNn. Angular deformation was consistently greater with smaller ILN. Screwed ILN constructs sustained approximately 2 x the torsional deformation of the bolted ones (approximately 36 degrees [ILN6s] versus approximately 18 degrees [ILN6b]). Comparatively, ILNn constructs had significantly less torsional (approximately 8 degrees) and bending (approximately 4 degrees) deformation than other constructs. Whereas standard ILN constructs had slack in both modes, ILNn and br-DCP construct deformations consistently occurred without slack.

CONCLUSIONS

Use of bolts rather than screws improved ILN mechanical behavior, but neither locking mechanism completely counteracted torsion and bending forces. Conversely, the ILNn angle-stable locking system eliminated torsional and bending slack, resulting in comparable mechanical performances between ILNn and plated constructs.

CLINICAL RELEVANCE

The angle-stable locking mechanism of the new ILN eliminates all slack in the system; thus, interfragmentary motion will likely be reduced compared with standard ILN, which may improve the local environment for fracture healing.

In vitro biomechanical comparison of a plate-rod combination-construct and an interlocking nail-construct for experimentally induced gap fractures in canine tibiae

OBJECTIVE

To compare structural properties of a plate-rod combination-bone construct (PRCbc) and interlocking nail-bone construct (ILNbc) by use of an experimentally induced gap fracture in canine tibiae.

SAMPLE POPULATION

12 paired canine tibiae.

PROCEDURE

Specimens were implanted with a plate-rod combination consisting of a 3.5-mm, limited-contact, dynamic-compression plate combined with an intramedullary rod or 6-mm interlocking nail. Ostectomy (removal of 10-mm segment) was performed. Paired constructs were loaded for bending, compression, or torsion measurements (4 constructs/group). Compliance was determined by fitting regression lines to the load-position curves at low (initial compliance) and high (terminal compliance) loads.

RESULTS

Bending compliances did not differ significantly between constructs. For the ILNbc, initial compliance was greater than terminal compliance in compression and torsion. Initial compliance and terminal compliance for the PRCbc were similar in compression and torsion. Initial compliance in compression and torsion was greater for the ILNbc, compared with initial compliance for the PRCbc. Maximum deformations in bending and compression were similar between constructs; however, maximum torsional angle was significantly greater for the ILNbc, compared with values for the PRCbc.

CONCLUSIONS AND CLINICAL RELEVANCE

The study documented that for an experimentally induced gap fracture in canine tibiae, a plate-rod combination is a significantly less compliant fixation method in torsion and compression, compared with an interlocking nail. Considering the deleterious effects of torsional deformation on bone healing, a plate-rod combination may represent a biomechanically superior fixation method, compared with an interlocking nail, for the treatment of dogs with comminuted tibial diaphyseal fractures.

In vitro mechanical evaluation of torsional loading in simulated canine tibiae for a novel hourglass-shaped interlocking nail with a self-tapping tapered locking design

OBJECTIVE

To describe a novel interlocking nail (ILN) and locking system and compare the torsional properties of constructs implanted with the novel ILN or a standard 8-mm ILN (ILN8) by use of a gap-fracture model.

SAMPLE POPULATION

8 synthetic specimens modeled from canine tibiae.

PROCEDURES

An hourglass-shaped ILN featuring a tapered locking mechanism was designed. A synthetic bone model was custom-made to represent canine tibiae with a 50-mm comminuted diaphyseal fracture. Specimens were repaired by use of a novel ILN or an ILN8 with screws. Specimens were loaded for torsional measurements. Construct compliance and angular deformation were compared.

RESULTS

Compliance of the ILN8 was significantly smaller than that of the novel ILN. Mean +/- SD maximum angular deformation of the ILN8 construct (23.12 +/- 0.65 degrees) was significantly greater, compared with that of the novel ILN construct (9.45 +/- 0.22 degrees). Mean construct slack for the ILN8 group was 15.15 +/- 0.63 degrees, whereas no slack was detected for the novel ILN construct. Mean angular deformation for the ILN8 construct once slack was overcome was significantly less, compared with that of the novel ILN construct.

CONCLUSIONS AND CLINICAL RELEVANCE

Analysis of results of this study suggests that engineering of the locking mechanism enabled the novel hourglass-shaped ILN system to eliminate torsional instability associated with the use of current ILNs. Considering the potential deleterious effect of torsional deformation on bone healing, the novel ILN may represent a biomechanically more effective fixation method, compared with current ILNs, for the treatment of comminuted diaphyseal fractures.

Thoracoscopic Lung Lobectomy for Treatment of Lung Tumors in Dogs

OBJECTIVE

To report use of thoracoscopic lung lobectomy (TLL) for treatment of lung tumors (LT) in dogs.

STUDY DESIGN

Retrospective study.

ANIMALS

Nine dogs.

METHODS

Dogs that had TLL for tumor removal were included. Using general anesthesia and 1-lung ventilation, TLL was performed using a 30-60 mm endoscopic gastrointestinal anastomosis stapler. If the visual field was obscured, lobe resection was completed via thoracotomy.

RESULTS

Metastatic and primary LT were resected by thoracoscopic lobectomy in 9 dogs (6 male, 3 female; mean (+/-SD) weight, 29+/-7 kg; mean age, 10.7+/-1.9 years). Six dogs had a solitary mass and 3 dogs had 2 masses within a single lobe. The left caudal lobe was removed in 3 dogs. In 5 dogs, TLL was used alone whereas conversion to thoracotomy was required in 4 dogs because of poor visibility. There were 7 metastatic LT and 2 primary LT. Mean duration of thoracoscopic surgery was 108.8+/-30.3 minutes compared with 150.75+/-55.4 minutes in dogs requiring conversion to thoracotomy. Mean hospitalization was 3.1+/-1.3 days.

CONCLUSION

Provided the visual field is not obscured, TLL can be performed effectively in dogs.

CLINICAL RELEVANCE

Dogs with metastatic or primary LTs should be considered for TLL, particularly for small masses positioned away from the hilus in the left caudal lung lobe.

Comparison of two laparoscopic suture patterns for repair of experimentally ruptured urinary bladders in normal neonatal calves

OBJECTIVE

To compare 2 laparoscopic suture patterns for repair of experimentally ruptured urinary bladders in normal neonatal calves.

STUDY DESIGN

Experimental surgical study.

ANIMALS

Thirty male Holstein calves.

METHODS

A bladder defect was created in 24 anesthetized calves (day 0). They were randomly divided into 4 groups (n=6/group). In groups 1 and 3, the defect was closed laparoscopically using a one layer full thickness simple continuous (FTSC) suture pattern (pattern A). In groups 2 and 4, the defect was closed laparoscopically in 2 layers using a FTSC suture pattern followed by Lembert continuous suture pattern (pattern B). Groups 1 and 2 calves were euthanatized at the end of the surgery and groups 3 and 4 at day 10. Six healthy calves were also euthanatized and used as a control group. The bladders were harvested and tested for bursting strength (BS). The surgical time (ST) data from the two groups for each pattern were pooled. A Student t-test was used to compare ST data. For the BS data, a 2-factor ANOVA test with post-hoc Student t-test was used to determine if treatment, time, or treatment-time interaction was significant. A Dunnett's test was used to compare BS of the 4 treatment groups to the control group. P<.05 was considered significant.

RESULTS

Mean ST was significantly shorter for pattern A than for pattern B. In all treatment groups, the mean bladder BS (MBBS) was significantly lower than the MBBS for the control group. The MBBS was significantly lower for group 1 than for group 2. There was no significant difference in the MBBS between groups 3 and 4.

CONCLUSION

In this study, a 1-layer laparoscopic closure technique had advantages compared with 2-layer laparoscopic closure technique. Further work is required before a 1-layer laparoscopic closure technique can be recommended clinically.

CLINICAL RELEVANCE

One-layer bladder closure is fast and safe in clinically normal calves and permits additional research to evaluate its safety in foals and clinical ruptures.

Epidural migration of new methylene blue in 0.9% sodium chloride solution or 2% mepivacaine solution following injection into the first intercoccygeal space in foal cadavers and anesthetized foals undergoing laparoscopy

OBJECTIVE

To determine the relationship between epidural cranial migration and injectate volume of an isotonic solution containing dye in laterally recumbent foal cadavers and evaluate the cranial migration and dermatome analgesia of an epidural dye solution during conditions of laparoscopy in foals.

ANIMALS

19 foal cadavers and 8 pony foals.

PROCEDURES

Foal cadavers received an epidural injection of dye solution (0.05, 0.1, 0.15, or 0.2 mL/kg) containing 1.2 mg of new methylene blue (NMB)/mL of saline (0.9% NaCl) solution. Length of the dye column and number of intervertebral spaces cranial and caudal to the injection site were measured. Anesthetized foals received an epidural injection of dye solution (0.2 mL/kg) containing saline solution or 2% mepivacaine. Foals were placed in a 100 head-down position, and pneumoperitoneum was induced. Dermatome analgesia was determined by use of a described electrical stimulus technique. Foals were euthanatized, and length of the dye column was measured.

RESULTS

Epidural cranial migration of dye solution in foal cadavers increased with increasing volume injected. No significant difference was found in epidural cranial migration of a dye solution (0.2 mL/kg) between anesthetized foals undergoing conditions of laparoscopy and foal cadavers in lateral recumbency. Further craniad migration of the dye column occurred than indicated by dermatome analgesia.

CONCLUSIONS AND CLINICAL RELEVANCE

Epidural cranial migration increases with volume of injectate. On the basis of dermatome analgesia, an epidural injection of 2% mepivacaine (0.2 mL/kg) alone provides analgesia up to at least the caudal thoracic dermatome and could permit caudal laparoscopic surgical procedures in foals.

Comparison of two laparoscopic treatments for experimentally induced abdominal adhesions in pony foals

OBJECTIVE

To compare laparoscopic dissection with-laparoscopic dissection combined with abdominal instillation of ferric hyaluronate gel for the treatment of experimentally induced adhesions in pony foals.

ANIMALS

12 healthy pony foals.

PROCEDURE

A serosal abrasion method was used to create adhesions at 4 sites on the jejunum (day 0). At day 7 laparoscopy was performed and the adhesions observed in each foal were recorded. In group-1 foals (n = 6), the adhesions were separated laparoscopically (treatment 1). In group-2 foals (n = 6), 300 mL of 0.5% ferric hyaluronate gel was infused into the abdomen after the adhesions were separated laparoscopically (treatment 2). At day 24, terminal laparoscopy was performed and the adhesions observed were recorded. Total number of adhesions within each group was compared between day 7 and 24. Data were analyzed to determine whether an association existed between the number of adhesions on day 24 and treatment type.

RESULTS

At day 24, the number of adhesions was significantly decreased within each group, compared with the number of adhesions at day 7 (group-1 foals, 10 vs 22 adhesions; group-2 foals, 3 vs 20 adhesions). Treatment 1 was associated with a significantly higher number of adhesions at day 24, compared with treatment 2 (odds ratio, 4.54; 95% confidence interval, 1.03 to 23.02).

CONCLUSION AND CLINICAL RELEVANCE

Abdominal instillation of 0.5% ferric hyaluronate gel after laparoscopic dissection was a more effective technique than laparoscopic dissection alone to treat experimentally induced adhesions in pony foals. Laparoscopic adhesiolysis following abdominal surgery in foals is a safe and effective technique.

Outcome of epidural catheterization for delivery of analgesics in horses: 43 cases (1998-2001)

OBJECTIVE

To determine reasons for epidural catheter placement among horses examined at a veterinary teaching hospital, efficacy of epidural administration of analgesics, duration of catheter placement, reasons for catheter removal, and complications encountered.

DESIGN

Retrospective study.

ANIMALS

43 horses.

PROCEDURE

Medical records were reviewed.

RESULTS

A total of 50 epidural catheters were placed in the 43 horses. Underlying conditions included fractures, lacerations, septic arthritis, myositis, perineal injuries, and cellulitis. Horses ranged from 2 to 21 years old and weighed between 365 and 795 kg (803 and 1,749 lb). Median duration of catheter placement was 96 hours (range, 1.5 to 480 hours). The response to epidural drug administration was reported as positive in 34 horses and negative in 4. There was no apparent response in 2 horses, and response could not be determined in 3. Three temporary patient-related complications associated with epidural catheter administration were observed. Technical problems associated with the epidural catheters included dislodgement of the catheter itself (7 catheters) or of the adapter or filter (5), obstruction (5), and leakage (5). Twenty-two catheters were removed because of resolution of the underlying condition, and 10 were removed because of complications. For 6 catheters, the reason for catheter removal was not recorded. The remaining 12 catheters were in place when the horses were euthanatized.

CONCLUSIONS AND CLINICAL RELEVANCE

Results suggest that epidural catheterization can be used successfully for repeated epidural delivery of analgesics and anesthetics in horses with various clinical conditions. Complications associated with epidural catheters or epidural drug administration were infrequent and transient.

Evaluation of laparoscopic adhesiolysis for the treatment of experimentally induced adhesions in pony foals

OBJECTIVE

To assess the efficacy of laparoscopic adhesiolysis in the treatment of experimentally induced adhesions in foals.

ANIMALS

8 healthy pony foals.

PROCEDURE

Celiotomy was performed and adhesions created at the jejunoileal junction and at sites 0.5 and 1 m proximal to this junction, using a serosal abrasion method. Ten days after celiotomy, exploratory laparoscopy was performed. Laparoscopic adhesiolysis was performed in the treatment group only (4 foals, randomly selected). Thirty days after the exploratory laparoscopy, a final laparoscopic examination was performed, and the foals were euthanatized. The number and characteristics of abdominal adhesions were recorded during laparoscopy 10 and 30 days after celiotomy and during necropsy.

RESULTS

At 30 days after celiotomy, the number of adhesions in the control group was significantly higher than the number in the treatment group. In the control group, all adhesions observed during the exploratory laparoscopy were still evident at the final laparoscopy and necropsy. In the treatment group, adhesions did not form again after separation. During final laparoscopy and necropsy, a focal adhesion between the omentum and site of the initial laparoscope portal was observed in 5 of 8 foals.

CONCLUSIONS AND CLINICAL RELEVANCE

The serosal abrasion model is useful for studying abdominal adhesions in foals. Laparoscopic adhesiolysis was an effective technique to break down experimentally induced adhesions in the early maturation stage of formation in pony foals. Studies are required to investigate prevention of de novo adhesions at the laparoscope portal sites.