Matthew D. Winter

Retrospective comparison between minimally invasive plate osteosynthesis and open plating for tibial fractures in dogs

OBJECTIVES To compare fracture healing in diaphyseal tibial fractures stabilized using either minimally invasive plate osteosynthesis (MIPO) or open reduction and internal fixation (ORIF). METHODS Dogs in each group were matched for type of fracture, age and body weight. Stage of healing was measured blindly every four weeks postoperatively until complete healing. Outcome variables including fracture length, plate length, plate bridging ratio, plate working length, healing grading, and fracture reduction were compared between groups using the Mann-Whitney test. Significant difference was set at p <0.05. RESULTS Based on the definition of clinical union, at 30 days five out of eight dogs managed with MIPO had healed, while two of the eight of dogs managed with ORIF had healed. We did not find any significant differences in the other outcome measures. No complications were reported in the MIPO group whereas one major complication was reported in the ORIF group. CLINICAL SIGNIFICANCE All dogs treated by MIPO healed rapidly without any complications, nevertheless the difference in radiographic healing between the two groups was not significant.

Assessment of fracture healing after minimally invasive plate osteosynthesis or open reduction and internal fixation of coexisting radius and ulna fractures in dogs via ultrasonography and radiography

OBJECTIVE To evaluate fracture healing after minimally invasive plate osteosynthesis (MIPO) or open reduction and internal fixation (ORIF) of coexisting radius and ulna fractures in dogs via ultrasonography and radiography. DESIGN Prospective cohort study. ANIMALS 16 dogs with radius-ulna fractures that underwent MIPO (n = 9; 2 dogs were subsequently not included in the analyses because of incomplete follow-up information) or ORIF (7). PROCEDURES Dogs in the 2 treatment groups were matched by age, body weight, and configuration of the fractures. Fracture healing was evaluated with ultrasonography, power Doppler ultrasonography, and radiography every 3 to 4 weeks until healing was complete; a semiquantitative score based on the number of Doppler signals was used to characterize neovascularization, and subjective B-mode ultrasonographic and radiographic scores were assigned to classify healing. RESULTS Fractures in dogs that underwent MIPO healed in significantly less time than did fractures in dogs that underwent ORIF (mean ± SD; 30 ± 10.5 days and 64 ± 10.1 days, respectively). Radiography revealed that fractures in dogs that underwent MIPO healed with significantly more callus formation than did fractures in dogs that underwent ORIF. Although Doppler ultrasonography revealed abundant vascularization in fractures that were healing following MIPO, no significant difference in neovascularization scores was found between groups. CONCLUSIONS AND CLINICAL RELEVANCE For dogs with radius-ulna fractures, data indicated that bridging osteosynthesis combined with a minimally invasive approach contributed to rapid healing after MIPO. The MIPO technique may offer some clinical advantage over ORIF, given that complete radius-ulna fracture healing was achieved in a shorter time with MIPO.

Ultrasonographic evaluation of relative gastrointestinal layer thickness in cats without clinical evidence of gastrointestinal tract disease

The objectives of this study were (1) to measure normal thickness values of the muscularis, submucosal, mucosal and serosal layers in each gastrointestinal (GI) segment (gastric fundus, body and pyloric antrum; duodenum; jejunum; ileum; colon), and (2) to calculate a ratio of muscularis and mucosal layer thickness to aortic diameter measured at the level of the celiac artery (Musc:Ao and Muc:Ao) in each GI segment in a sample of healthy cats. Ultrasonographic examination of the GI tract was performed, and measurements of the individual layers in each GI segment were obtained in 38 healthy cats without clinical evidence of disease. The muscularis layer was significantly thickest in the ileum, compared with other segments, and it was thicker than the submucosa in all segments except the colon. The mucosa was the thickest layer in all segments, and was thickest in the duodenum and ileum. Measurements of the submucosal and serosal layers were not significantly different between all segments. Musc:Ao and Muc:Ao in each segment were 0.12 and 0.25 (gastric fundus), 0.12 and 0.18 (gastric body), 0.11 and 0.16 (pyloric antrum), 0.08 and 0.27 (duodenum), 0.08 and 0.22 (jejunum), 0.14 and 0.25 (ileum), and 0.05 and 0.08 (colon), respectively. Musc:Ao and Muc:Ao are clinically relevant values that can be used to objectively identify thickening of the muscularis and mucosal layers in response to GI diseases.

Radiographic quantitative assessment of cranial tibial subluxation before and after tibial plateau leveling osteotomy in dogs

OBJECTIVE To determine the influence of stifle joint flexion angle, cranial cruciate ligament (CrCL) integrity, tibial plateau leveling osteotomy (TPLO), and cranial tibial subluxation on the distance between the location of the origin and insertion of the CrCL (CrCL(d)) in dogs. SAMPLES 4 pairs of pelvic limbs from adult dog cadavers weighing 23 to 34 kg. Procedures-Mediolateral projection radiographs of each stifle joint were obtained with the joint flexed at 90°, 105°, 120°, 135°, and 150°. Radiopaque markers were then placed at the sites of origin and insertion of the CrCL. Afterward, radiography was repeated in the same manner, before and after CrCL transection, with and without TPLO. Following CrCL transection, radiographs were obtained before and after inducing overt cranial tibial subluxation. Interobserver variation in measuring the CrCL(d) without fiduciary markers was assessed. The effect of CrCL integrity, cranial tibial subluxation, flexion angle, and TPLO on CrCL(d) was also determined. RESULTS Interobserver agreement was strong, with an intraclass correlation coefficient of 0.859. The CrCL(d) was significantly shorter (< 1 mm) at 90° of flexion; otherwise, flexion angle had no effect on CrCL(d). Cranial tibial subluxation caused a 25% to 40% increase in CrCL(d). No effect of TPLO on CrCL(d) was found, regardless of CrCL integrity, forced stifle joint subluxation, or flexion angle. CONCLUSIONS AND CLINICAL RELEVANCE Overt cranial tibial subluxation in CrCL-deficient stifle joints can be detected on mediolateral projection radiographs by comparing CrCL(d) on neutral and stressed joint radiographs at joint angles between 105° and 150°, regardless of whether a TPLO has been performed.

ULTRASOUND APPEARANCE OF THE OUTER MEDULLA IN DOGS WITHOUT RENAL DYSFUNCTION

Ultrasound findings of the canine kidney include a hyperechoic cortex and a hypo to anechoic medulla. In this study, the sonographic appearance of the outer renal medulla in dogs without evidence of renal disease is described. Dogs that underwent abdominal ultrasound over a 6-month period were subjected to review and then divided into six groups based on body weight (kg): < 4.9, 5.0-9.9, 10-19.9, 20-29.9, 30-39.9, and ≥ 40. Chi-square analysis was used to determine if the frequency of a hyperechoic outer medulla was significantly different between weight groups, sex, and age (P-value < 0.05). Of the 145 dogs that met the inclusion criteria, 45 had a hyperechoic outer medulla relative to the cortex and inner medulla. In the remaining dogs, the outer medulla was isoechoic to the cortex. Dogs less than 5 kg had the highest frequency of a hyperechoic outer medulla (P < 0.0001) and dogs greater than 40 kg did not have a hyperechoic outer medulla (P < 0.0001). Sex had no influence on the presence or absence of the hyperechoic outer medulla; however, younger dogs were overrepresented (6.4 ± 0.6 years compared with 7.8 ± 0.4 years; P = 0.04). Ultrasound descriptions of the canine kidney have not taken into account the contributions of the renal cortex and outer medulla. Based on this study of dogs with no clinically significant renal disease, the outer medulla can be isoechoic or hyperechoic to the cortex and a hyperechoic outer medulla is more commonly seen in small breed dogs.

Original Study: Comparison of three intraosseous access techniques in cats

OBJECTIVE To compare the placement feasibility and amount of bone trauma induced by 3 intraosseous (IO) access techniques in cats: an automatic impact penetration device (A), an automatic rotary insertion device (B), and a manual IO needle (C). DESIGN Prospective ex vivo study. SETTING University. ANIMALS Eighteen adult mixed breed feline cadavers. INTERVENTIONS Cadavers provided 72 total IO insertion locations divided equally between the right and left humerus and tibia. The 3 IO techniques were randomly allocated to these locations. Time to successful insertion, ease of insertion, and success rate were recorded. Each insertion site was analyzed for the number of bone fragments and defect diameter by computed tomography. MEASUREMENTS AND MAIN RESULTS Device B had lower time of insertion (P=0.01) compared with devices A and C. Device B had better ease of insertion scores (P<0.01) compared with devices A and C. No differences were detected between insertion sites (tibia versus humerus). No differences in the number of bone fragments, defect diameter, or success rate were detected among devices (P=0.06, 0.31, and 0.14, respectively). CONCLUSIONS All 3 IO access methods evaluated yield acceptable results. Device B is significantly faster and easier to place in cat cadavers when compared with other methods.

Unilateral orbital lacrimal gland abscess in a horse

A 20-year-old Thoroughbred gelding presented for evaluation of a periorbital dorsal swelling of the left eye that had been intermittently present for 3 months. Upon ocular examination, a firm, non-painful swelling was identified under the upper eyelid in the region of the orbital lacrimal gland, and was noted to extend anteriorly from underneath the dorsal orbital rim. Ultrasonographic examination revealed a mixed echogenic mass along the dorsal orbital rim that followed the contour of the globe. CT scan showed a moderately contrast enhancing mass that was contiguous with the eyelid. Differential diagnoses included neoplasia, inflammatory lesions such as a granuloma, foreign body or abscess. Surgical exploration and excision of the mass revealed a lobular structure with a purulent center. Histopathology identified the mass as the orbital lacrimal gland with concurrent severe dacryoadenitis. Culture of the purulent center of the mass revealed beta-hemolytic Staphylococcus aureus. The patient was maintained on supportive care and antibiotic treatment based on sensitivity postoperatively. No recurrence was reported 40 months later. This paper aims to identify bacterial dacryoadenitis as a cause for unilateral periorbital swelling in the horse. Differential diagnoses for this presentation, as well as successful surgical management are discussed. To the authors knowledge, this is the first case of bacterial dacryoadenitis and subsequent abscessation of the orbital lacrimal gland in the horse.

Intra- and interobserver variability of board-certified veterinary radiologists and veterinary general practitioners for pulmonary nodule detection in standard and inverted display mode images of digital thoracic radiographs of dogs.

OBJECTIVE To determine intra- and interobserver variability of 2 veterinary radiologists and 2 veterinary general practitioners for detection of pulmonary nodules in standard and inverted (reversed grayscale) displays of digital thoracic radiographs of dogs. DESIGN Evaluation study. SAMPLE 114 sets of 3-view (right lateral, left lateral, and ventrodorsal or dorsoventral views) digital thoracic radiographs from 114 dogs. PROCEDURES 2 experienced board-certified veterinary radiologists and 2 experienced veterinary general practitioners individually evaluated 114 randomized sets of radiographs. Pulmonary nodules were present in radiographs of 60 of 114 dogs. Each reviewer examined all images in standard or inverted display mode and scored nodule detection on a confidence scale of 1 to 5. After ≥ 2 months, the same individuals evaluated the same images in the remaining display mode. Intraobserver agreement for each display mode was determined via a κ statistic; results between the 2 groups of reviewers were compared via receiver operator curve analysis. RESULTS There was no significant intraobserver variability in pulmonary nodule detection between the 2 display modes. Detection accuracy for board-certified radiologists was significantly greater than that of veterinary general practitioners for both display modes. Near-perfect intraobserver agreement was detected between the 2 display modes for board-certified radiologists, whereas moderate to slight intraobserver agreement was detected for the veterinary general practitioners. CONCLUSIONS AND CLINICAL RELEVANCE Detection of pulmonary nodules in digital thoracic radiographs was comparable, whether a standard or inverted mode was used for evaluations. However, the board-certified radiologists had greater detection accuracy than did veterinary general practitioners.

Effect of sedation protocol on glomerular filtration rate in cats as determined by use of quantitative renal scintigraphy.

OBJECTIVE To evaluate the effect of several sedation protocols on glomerular filtration rate (GFR) in cats as measured by use of quantitative renal scintigraphy and to analyze interobserver differences in GFR calculation. ANIMALS 5 cats (1 sexually intact male, 1 neutered male, and 3 sexually intact females). PROCEDURES Effects on GFR of 3 sedation protocols commonly used at the Iowa State University College of Veterinary Medicine were evaluated. The protocols were medetomidine (11 μg/kg) and butorphanol tartrate (0.22 mg/kg) administered i.m.; ketamine hydrochloride (10 mg/kg) and midazolam (0.5 mg/kg) administered i.v.; and ketamine (10 mg/kg), midazolam (0.5 mg/kg), and acepromazine maleate (0.05 mg/kg) administered i.m.. Results for the 3 protocols were compared with results of GFR measurements obtained in these same cats without sedation (control protocol). RESULTS No significant difference between GFR measurements was associated with the 3 sedation protocols, compared with GFR measurements for the control protocol. The greatest mean GFR values were for the medetomidine-butorphanol and ketamine-midazolam protocols. There were no significant differences between observers for calculation of GFR. CONCLUSIONS AND CLINICAL RELEVANCE Results suggested that none of the 3 sedation protocols had significant effects on GFR calculated by use of quantitative renal scintigraphy, compared with results for GFR evaluations performed in the cats when they were not sedated. No significant interobserver error was evident. However, the statistical power of this study was low, and the probability of a type II error was high.

Use of a Linear-Circular Hybrid External Skeletal Fixator for Stabilization of a Juxta-Physeal Proximal Radial Fracture in a Deer (Odocoileus virginianus)

Abstract This report documents the successful use of a hybrid linear-circular fixator for the stabilization of a closed, oblique, comminuted fracture of the proximal right radial diaphysis in a 3-mo-old female deer (Odocoileus virginianus). Under fluoroscopic guidance, a hybrid fixator was applied for fracture stabilization, with consideration given to the risk of inducing further fissuring of the proximal segment, attaining adequate fixation in the short juxta-physeal segment, and possibly disrupting physeal growth. Three divergent wires were used as ring fixation elements to secure the proximal fracture segment. Mild fissure propagation occurred during fixation pin placement. All subsequent fixation pins chosen were of a smaller diameter and were placed without further deterioration of the existing fissures. Although willing to ambulate upon recovery, the deer placed the dorsum of the hoof on the ground initially after surgery, which resolved by the sixth day. The hybrid fixator was well-tolerated and was removed 4 wk postoperatively. In addition, proximal radial physeal growth was not disrupted and both radii had similar lengths after fixator removal. Hybrid linear-circular external skeletal fixation was advantageous for stabilization of the juxta-physeal fracture in this deer; with appropriate application techniques and configuration, we believe that hybrid fixators can be used successfully in several wildlife species with maximum acceptance and minimal complications.