Katy L. Townsend

Cemented Total Knee Replacement in 24 Dogs: Surgical Technique, Clinical Results, and Complications

OBJECTIVE To characterize the performance of cemented total knee replacement (TKR) in dogs. STUDY DESIGN Preclinical research study. ANIMALS Skeletally mature, male Hounds (25-30 kg; n=24) with no preexisting joint pathology. METHODS Dogs had unilateral cemented TKR and were evaluated at 6, 12, 26, or 52 weeks (6 dogs/time point) by radiography, bone density analysis, visual gait assessment, and direct measurement of thigh circumference and stifle joint range of motion as indicators of functional recovery. At study end, the stability of the cemented tibial component was determined by destructive mechanical testing. RESULTS Joint stability was excellent in 16 dogs (67%) and good in 8 dogs. None of the tibial components had evidence of migration or periprosthetic osteolysis whereas 1 femoral component was loose at 52 weeks. There was an early and significant decrease in tibial bone density, likely because of disuse of the operated limb. Dogs returned to full activity by 12 weeks. The tibial cement-bone interface maintained its strength over 52 weeks. CONCLUSIONS Cement provides stable fixation of the tibial component in canine TKR. CLINICAL RELEVANCE Cemented TKR yields adequate clinical function and stifle joint excursion in the dog. Clinical studies are needed to determine the long-term fate of cemented TKR implants, to assess the influence of implant design on implant fixation and wear, and to obtain objective functional data.

Current Concepts in Minimally Invasive Surgery of the Abdomen

Minimally invasive surgery of the abdomen constitutes an increasingly common and developed set of surgical options in small animal veterinary patients. In addition to established procedures, such as laparoscopic gonadectomy and biopsies, more advanced procedures, such as adrenalectomy, cholecystectomy, cisterna chyli ablation, and lymph node extirpation, are described. Some laparoscopic procedures have been reported using different techniques or approaches, reflecting the fields progression beyond its infancy. Advances in equipment and experience among an ever-growing group of veterinary surgeons are expected to result in progressively more widespread adoption of minimally invasive procedures.

Effect of Metoclopramide on the Incidence of Early Postoperative Aspiration Pneumonia in Dogs with Acquired Idiopathic Laryngeal Paralysis.

OBJECTIVE Evaluate the effect of a perioperative intravenous continuous rate infusion (CRI) of metoclopramide on the incidence of aspiration pneumonia in the short term postoperative period in dogs undergoing unilateral arytenoid lateralization. STUDY DESIGN Prospective, randomized, multi-center clinical trial. ANIMALS 61 client-owned dogs with idiopathic laryngeal paralysis and normal preoperative thoracic radiographs. METHODS All dogs underwent unilateral arytenoid lateralization with a uniform anesthetic, analgesic, and management protocol. Dogs in the treatment group received an intravenous CRI of metoclopramide for 24 hours perioperative. All dogs were assessed for clinical signs of aspiration pneumonia based on the results of physical examination and owner interview up to the point of suture removal (10-14 days postoperative). Any dog with suspected aspiration pneumonia had thoracic radiographs performed. RESULTS Six dogs developed aspiration pneumonia in the short term postoperative period (2/28 control dogs and 4/33 treated dogs), accounting for an overall frequency of 10% with no significant difference between control and treated dogs. No variables measured in the study were significantly different between control and treated dogs. CONCLUSIONS Perioperative metoclopramide, at the doses used in this study, did not affect the incidence of aspiration pneumonia in the short term postoperative period in dogs with idiopathic laryngeal paralysis undergoing unilateral arytenoid lateralization.

Reductions in margin length after excision of grade II mast cell tumors and grade I and II soft tissue sarcomas in dogs

OBJECTIVE Quantify changes in the circumferential lengths of surgical margins of resected canine mast cell tumors (MCT) and soft tissue sarcomas (STS) between the time of collection and histopathology. STUDY DESIGN Prospective, hypothesis-driven, clinical study. SAMPLE POPULATION Two hundred and thirty-seven margins from 69 excised tumors (50 MCT and 19 STS) in 51 client-owned dogs. METHODS The lengths of surgical margins were recorded (eg, cranial, caudal, dorsal, and ventral) for each tumor at 5 time points: intraoperatively (in vivo), immediately after excision (ex vivo), after formalin fixation (postfixation), once mounted on glass slides (subgross), and as histologically tumor-free margins (HTFMs). RESULTS Compared to in vivo dimensions, the length of surgical margins at each processing step (ie, ex vivo, postfixation, subgross, and HTFM) was reduced by a median of 3.0, 5.0, 6.0, and 8.8 mm for MCT; 2.5, 2.0, 5.0, and 5.0 mm for STS. All processing steps resulted in significant reductions among MCT samples (P < .0001), except between postfixation vs subgross, and for STS samples (P < .0001), except between ex vivo vs postfixation and subgross vs HTFM. The maximum reduction in the total length of margins (from in vivo to HTFM) was 29.6 and 24.2 mm for MCT and STS, respectively. CONCLUSION Surgical margin length reductions occur due to a combination of physical factors (eg, tissue elasticity, myofibril contraction, and histologic processing) and biological factors (eg, microscopic tumor infiltration into the grossly normal surgical margin). CLINICAL SIGNIFICANCE These data provide information relevant to evidence-based surgical planning and may influence patient morbidity in the most commonly encountered cutaneous malignancies of dogs.

Comparison of major complication and survival rates between surgical ligation and use of a canine ductal occluder device for treatment of dogs with left-to-right shunting patent ductus arteriosus

OBJECTIVE To compare rates of major intraoperative complications and survival to hospital discharge between surgical ligation (SL) and canine ductal occluder (CDO) implantation for treatment of dogs with left-to-right shunting patent ductus arteriosus (PDA). DESIGN Retrospective cohort study. ANIMALS 120 client-owned dogs with left-to-right shunting PDA (62 treated by SL and 58 treated by CDO implantation). PROCEDURES Data were retrieved from medical records of included dogs regarding signalment, medical history, vertebral heart scale, preoperative echocardiographic findings, complications encountered during surgery, and durations of anesthesia and surgery (SL or CDO implantation). Data were compared between dogs treated by SL and those treated by CDO implantation. RESULTS Dogs treated by CDO implantation were significantly older and heavier than dogs treated by SL and had more pathological cardiac remodeling (as indicated by mitral regurgitation scores, left atrial-to-aortic root diameter ratios, and fractional shortening values). Durations of anesthesia and surgery were also significantly longer for CDO implantation versus SL. The major complication rate for dogs treated by SL (6/62 [10%]) was significantly greater than that for dogs treated by CDO implantation (0/58 [0%]). One dog in the SL group died during surgery. Overall rate of survival to hospital discharge was 99% (119/120). CONCLUSIONS AND CLINICAL RELEVANCE Both SL and CDO implantation were viable methods for PDA attenuation in the evaluated dogs. Although a greater proportion of dogs had major complications during the SL procedure, the 2 procedures had comparable rates of survival to hospital discharge.

Feasibility of near-infrared fluorescence imaging for sentinel lymph node evaluation of the oral cavity in healthy dogs

OBJECTIVE To evaluate the usefulness of injection of indocyanine green (ICG) solution with near-infrared (NIR) fluorescence imaging for transcutaneous detection of sentinel lymph nodes (SLNs) and their associated lymphatic vessels in the oral mucosa of healthy dogs. ANIMALS 6 adult purpose-bred research hounds. PROCEDURES Each dog was sedated, and 1 mL of ICG solution was injected into the gingival mucosa dorsal to the right maxillary canine tooth. Subsequently, NIR fluorescence imaging was used to transcutaneously detect the lymphatic vessels and SLNs. The distance between the injection site and each SLN was measured. Time to first evidence of node fluorescence was recorded, and velocity of ICG movement was calculated. A slide preparation of a fine-needle aspiration sample of the fluorescing structure underwent cytologic examination (to confirm presence of lymphatic tissue) and NIR fluorescence imaging (to confirm presence of ICG). RESULTS The ipsilateral mandibular lymphocentrum was the SLN in all dogs. The time to visually detectable fluorescence ranged from 4 to 15 minutes (mean ± SD, 8.8 ± 3.76 minutes). The mean velocity was 1.94 ± 0.93 cm/min. Fluorescence was not observed in the contralateral lymph nodes. Each fluorescing structure was confirmed to be lymphatic tissue, and NIR fluorescence imaging revealed that ICG was present in the sampled SLN. CONCLUSIONS AND CLINICAL RELEVANCE Results indicated that injection of ICG solution with NIR fluorescence imaging can be used to transcutaneously identify SLNs along with associated lymphatic vessels in the oral mucosa of healthy dogs. Time from injection to identification of fluorescence was rapid with prolonged retention of material within the SLN, indicating that this procedure could be performed during surgery.

Computed tomographic imaging and mechanical analysis of cellophane banding secured with locking polymer clips for portosystemic shunts in canine cadavers

OBJECTIVE To determine whether cellophane banding secured with locking polymer clips on cadaveric splenic veins would cause less CT imaging artifact and achieve equivalent mechanical strength, compared with cellophane banding secured with metal vascular clips. ANIMALS 10 canine cadavers. PROCEDURES Clips of each material were applied to each cadaver in a crossover design study. Triple-layer cellophane bands secured with 4 medium-large or large polymer or metal clips were placed on cadaveric splenic veins and evaluated by use of CT. Beam-hardening artifact was assessed by artifact length, attenuation, and a subjective grading scale ranging from 1 to 3 for mild to severe imaging artifacts. Secured cellophane bands were mechanically tested to determine force-deformation curves and yield forces. Findings for clip methods were compared with a 1-way ANOVA with a Tukey post-test. RESULTS For metal clips, beam-hardening artifact lengths and subjective artifact grades were significantly higher, whereas attenuation values were significantly lower, than findings for polymer clips. Polymer clips were significantly lower in strength than metal clips with mean ± SD yield loads of 1.9 ± 0.6 N (medium-large polymer clips), 2.8 ± 1.3 N (large polymer clips), 6.0 ± 1.9 N (medium-large metal clips), and 8.4 ± 2.7 N (large metal clips). CONCLUSIONS AND CLINICAL RELEVANCE Use of locking polymer clips to secure cellophane banding resulted in less CT imaging artifact and mechanical strength, compared with use of metal vascular clips. Use of locking polymer clips may allow improved assessment of postoperative CT imaging in dogs with extrahepatic portosystemic shunts, which warrants in vivo clinical evaluation.

Buried absorbable polyglactin 910 sutures do not result in stronger wounds in porcine full thickness skin incisions.

OBJECTIVE To test the hypothesis that the mechanical strength of wounds closed with a combination of buried dermal absorbable sutures and superficial nonabsorbable nylon sutures will be higher than wounds closed with only superficial nonabsorbable nylon sutures. METHODS Four Yucatan pigs were anesthetized and each received four 4.5cm full thickness incisions on their dorsal surfaces, placed 8cm apart. Half of all incisions were randomly allocated and repaired with 3-0 polyglactin 910 (Vicryl(™)) buried dermal absorbable sutures and superficial 3-0 nylon sutures, using a simple interrupted pattern. The other half received only 3-0 nylon sutures. Two pigs were humanely euthanized at day 10, with specimen harvest for mechanical testing; the other two pigs had superficial nylon sutures removed at day 10, as per current clinical practice, and were humanely euthanized at day 42, with specimen harvest for mechanical testing. Tensile loads were applied perpendicularly to the wounds with a displacement rate of 40mm per minute. RESULTS Wounds at day 42 were >9 times stronger than wounds at day 10 (p<0.0001). There was no difference in average wound strength at either day 10 or day 42 between wounds with and without buried dermal absorbable sutures. SIGNIFICANCE Buried dermal absorbable sutures failed to provide additional wound support at either 10 or 42 days. This result may have immediate implications for clinicians who perform cutaneous surgery and keep superficial sutures in for at least 10 days. Future research will be directed to shorter time studies, other buried dermal absorbable suture materials, and alternatives to buried dermal absorbable sutures.