Margret S. Thompson

COMPARISON OF RADIOGRAPHY AND ULTRASONOGRAPHY FOR DIAGNOSING SMALL‐INTESTINAL MECHANICAL OBSTRUCTION IN VOMITING DOGS

A cross-sectional study was performed on acutely vomiting dogs to compare the accuracy of radiography and ultrasonography for the diagnosis of small-intestinal mechanical obstruction and to describe several radiographic and ultrasonographic signs to identify their contribution to the final diagnosis. The sample population consisted of 82 adult dogs and small-intestinal obstruction by foreign body was confirmed in 27/82 (33%) dogs by surgery or necropsy. Radiography produced a definitive result (obstructed or not obstructed) in 58/82 (70%) of dogs; ultrasonography produced a definitive result in 80/82 (97%) of dogs. On radiographs, a diagnosis of obstruction was based on detection of segmental small-intestinal dilatation, plication, or detection of a foreign body. Approximately 30% (8/27) of obstructed dogs did not have radiographic signs of segmental small-intestinal dilatation, of which 50% (4/8) were due to linear foreign bodies. The ultrasonographic diagnosis of small-intestinal obstruction was based on detection of an obstructive lesion, sonographic signs of plication or segmental, small-intestinal dilatation. The ultrasonographic presence or absence of moderate-to-severe intestinal diameter enlargement (due to lumen dilatation) of the jejunum (>1.5 cm) was a useful discriminatory finding and, when present, should prompt a thorough search for a cause of small-intestinal obstruction. In conclusion, both abdominal radiography and abdominal ultrasonography are accurate for diagnosing small-intestinal obstruction in vomiting dogs and either may be used depending on availability and examiner choice. Abdominal ultrasonography had greater accuracy, fewer equivocal results and provided greater diagnostic confidence compared with radiography.

Evaluation of Tibial Torsion in Yorkshire Terriers with and without Medial Patellar Luxation

OBJECTIVE To determine if medial patellar luxation (MPL) in Yorkshire Terriers is associated with tibial torsion. STUDY DESIGN Prospective cross-sectional study. ANIMALS Yorkshire Terriers (n = 30; 60 tibiae). METHODS Each MPL was graded using a categorical grading scheme. Computed tomography of the tibiae was performed and tibial torsion angle (TTA) was assessed. MPL grade was analyzed with a general linear model where the independent variables include sex, neutering status, age, weight, and TTA. RESULTS Factors that had collective impact on MPL grade were TTA, age, and weight squared. As MPL grade increased, TTA decreased by 0.05° and age increased by 0.13 years. As weight increased, MPL decreased. There was no effect (P > .05) from scorers, side, and neutering status. CONCLUSION Body weight squared, TTA, and age affect MPL grade, suggesting that a torsional deformity may contribute to the development of MPL in Yorkshire terriers along with weight and age.

RELATIONSHIPS AMONG SUBGROSS ANATOMY, COMPUTED TOMOGRAPHY, AND HISTOLOGIC FINDINGS IN DOGS WITH DISEASE LOCALIZED TO THE PULMONARY ACINI

During computed tomography (CT), the appearance of disease involving the pulmonary acinus may be described using terms such as atelectasis, ground-glass opacity, or consolidation. These CT signs, however, have not been correlated with histologic findings in canine pulmonary disease. To facilitate interpretation of lung diseases by CT signs, our goals were to review the morphologic organization of the lung and evaluate the medical records of four dogs with different types of pulmonary acinar disease. Anatomic review focused on understanding the pulmonary acinus and the secondary pulmonary lobule; the secondary pulmonary lobule is a fundamental unit for interpretation in people. All dogs had similar CT findings of fully expanded lungs with increased attenuation and partial-to-complete obscuring of the pulmonary blood vessels. Histologic findings varied between dogs and included partial-to-complete filling of airspaces with cells or fluid, interstitial thickening, increased capillary blood volume, or a combination of these findings. Final diagnoses were hemorrhagic pneumonia, bronchiolar carcinoma, metastatic mammary adenocarcinoma, and pulmonary edema. In summary, the morphologic organization of the lungs is complex and has implications for diagnostic interpretation needing further evaluation in dogs. In this study, increased lung attenuation during CT due to disease localized to the pulmonary acini was due to the displacement of air from the lungs and not to the microscopic distribution of lesions within the pulmonary acinus. Imaging descriptors that classify diseases according to structures larger than the pulmonary acini, for example, regions of the secondary pulmonary lobule or larger, may be appropriate for dogs.

Cranial vena caval syndrome secondary to central venous obstruction associated with a pacemaker lead in a dog.

This report describes the case of an 11-year-old castrated male Shih Tzu who developed chylothorax three years following implantation of a transvenous pacemaker. Imaging demonstrated one definitive obstruction in the cranial vena cava and 3 additional suspected filling abnormalities within both external jugular veins, brachiocephalic veins and cranial vena cava. A thrombus was visualized in the cranial vena cava via transesophageal echocardiography. Thoracic duct ligation and cisterna chyli ablation were performed, with a resultant change in the nature of the fluid from chylous to a modified transudate. Repeat angiography and computed tomography three months later demonstrated a stenosis within the cranial vena cava. Balloon angioplasty was attempted, however it was unsuccessful in decreasing pleural effusion. Palliative thoracocentesis was continued until the patient developed a lung lobe torsion, at which time euthanasia was elected. Necropsy confirmed cranial vena caval syndrome secondary to transvenous pacemaker implantation induced fibrous proliferation within the vessel lumen.

NASOPHARYNGEAL MYXOSARCOMA IN A BENGAL TIGER (PANTHERA TIGRIS)

Abstract An 18- to 25-yr-old intact female Bengal tiger (Panthera tigris) was diagnosed antemortem and postmortem with nasopharyngeal myxosarcoma metastatic to the lung, chronic lymphoplasmacytic otitis media, and lymphoplasmacytic and eosinophilic stomatitis. Myxosarcomas are rare in domestic animals and seldom metastasize; this tumor has not been previously reported in an exotic felid. Computed tomography of the skull was used during the diagnoses.

Radiographic evaluation of cardiac size in flying fox species (Pteropus rodricensis, P. hypomelanus, and P. vampyrus).

Abstract Dilated cardiomyopathy is a relatively common pathology in captive flying foxes (Pteropus spp.). The goal of this study was to establish quantitative reference range measurements that could be used to support a diagnosis of cardiac disease in these animals. Lateral and ventrodorsal thoracic radiographs from apparently healthy flying foxes (n = 66) of three species (Rodriguez island flying fox, P. rodricensis, n = 18; small island flying fox, P. hypomelanus, n = 16; and Malaysian flying fox, P. vampyrus, n = 32) were evaluated objectively to describe the cardiac appearance. Absolute and relative cardiac dimensions also were measured. The same methods were used to evaluate radiographs from flying foxes (n = 9) with known dilated or acute cardiomyopathy. The following ratios were most appropriate for categorizing normal cardiac silhouette size. In the ventrodorsal projection, heart width to thoracic width and heart width to clavicle length were the preferred measurements. In the lateral projection, heart width compared with thoracic height was the preferred measurement. From radiographs of the bats with known dilated and acute cardiomyopathy, the apicobasilar heart length compared with thoracic height and heart width compared with thoracic height on lateral films were the most sensitive ratios for diagnosing cardiomegaly.

Dyspnea caused by epiglottic retroversion in two dogs

CASE DESCRIPTION An 8-year-old castrated male Boxer and a 10-year-old spayed female Yorkshire Terrier were evaluated because of dyspnea. In both dogs, the dyspnea persisted after elongated soft palate resection. CLINICAL FINDINGS Laryngoscopic examination revealed caudal displacement of the epiglottis into the rima glottidis in both dogs. Excessive mobility of the epiglottis during respiration with episodic obstruction of the rima glottidis by the epiglottis was observed during fluoroscopic examination. TREATMENT AND OUTCOME The epiglottis of both dogs was fixed in a horizontal plane by resection of a band of oral mucosa at the base of the epiglottis and closure of the mucosal defect with sutures. Fixation of the epiglottis resolved the dyspnea in both dogs. CLINICAL RELEVANCE Excessive mobility of the epiglottis can predispose to glottic obstruction and cause dyspnea in dogs. Fixation of the epiglottis in a horizontal plane may resolve dyspnea caused by epiglottic retroversion in dogs.

Cubital subchondral joint space width and CT osteoabsorptiometry in dogs with and without fragmented medial coronoid process.

OBJECTIVE To evaluate subchondral joint space width measurements (SJSW) and CT-osteoabsorptiometry (CTOAM) measurements in the elbow of dogs with naturally occurring fragmented medial coronoid process (FMCP) preoperatively and 6 months postoperatively, and to compare these to normal dogs. STUDY DESIGN Prospective randomized clinical trial. ANIMALS Large breed dogs <1 year of age (n = 15). METHODS Arthroscopic FMCP debridement was performed, followed by randomization to a proximal ulnar ostectomy with IM pin (PUO). CTs were performed pre-operatively and 6 months post-operatively. CTOAM and SJSW measurements were acquired in 7 locations within the joint and compared to an age-matched normal control group. Pearson correlation was performed on SJSW and CTOAM measurements. A linear mixed model determined the effect of disease and treatment on SJSW and CTOAM measurements. RESULTS Fifteen dogs (28 elbows) with FMCP participated (11 arthroscopic FMCP removal, 17 with additional PUO). Data were normally distributed. Pearson correlation between CTOAM and SJSW measurements showed moderate to strong negative correlation in the control dogs. Preoperatively, affected elbows had lower medial compartment and higher lateral coronoid process CTOAM values than normal elbows. After treatment, CTOAM values of the medial compartment increased to normal. Treatment with PUO did not affect SJSW or CTOAM. CONCLUSIONS Our data agree with these previous studies suggesting lower subchondral plate mineralization in dogs affected by FMCP. Arthroscopy may result in higher CTOAM values secondary to increased loading.

Comparison of Tibial PA, Bone Healing, and Intra-articular Screw Placement using Conventional Nonlocked Application of Surgeon-Contoured versus Locked Application of Precontoured TPLO Plates in Dogs

OBJECTIVE To determine the influence of conventional nonlocked application of surgeon-contoured (NL-SXc) and locked-hybrid application of precontoured (L-Pc)- TPLO plates on the tibial plateau angle (TPA) immediately postoperatively and longterm after tibial plateau leveling osteotomy (TPLO) in dogs as well as to evaluate their influence on the incidence of intra-articular screw placement and bone healing. STUDY DESIGN Retrospective, cross-sectional, clinical study. ANIMALS Dogs (n = 101) with cruciate ligament insufficiency that had TPLO. METHODS Collected data included signalment, plate size/type, preoperative (PreTPA), postoperative (PostTPA), and recheck TPA (ReTPA). Tibial plateau rotation achieved during surgery (RotaTPA = PreTPA-PostTPA) and TPA shift during healing (ShiftTPA = ReTPA-PostTPA) were calculated. Radiographic evidence of stability and time to radiographic recheck were recorded. Variables were compared by plate type using a 2-sample t-test or χ(2) as appropriate (significance at P < .05). RESULTS Median time to radiographic follow-up was 75 days (range, 43-2815 days). The remaining data are reported as means. Forty-two stifles had NL-SXc, 59 stifles had L-Pc. PreTPA of NL-SXc and L-Pc was 28.3° and 29.1°, respectively (P = .22). PostTPA (13.2° and 7.9°), RotaTPA (15.0° and 21.2°) and ReTPA (14.9° and 10.3°) for NL-SXc and L-Pc, respectively, were all significantly different (P< .0001). ShiftTPA for these constructs (1.7° and 2.4°, respectively) was not significantly different (P = .25), and 92.1% of dogs were considered to have radiographically stable osteotomies at last recheck. CONCLUSIONS A higher degree of tibial plateau rotation was achieved and maintained in osteotomies with L-Pc. There was no significant difference in ShiftTPA or radiographic osteotomy stability between constructs.

Effect of ulnar ostectomy on intra-articular pressure mapping and contact mechanics of the congruent and incongruent canine elbow ex vivo.

OBJECTIVE To determine (1) the effect of elbow incongruity on contact mechanics and (2) the effect of treatment of this incongruity with 1 of 2 ulnar ostectomies in the canine elbow. STUDY DESIGN Ex vivo biomechanical study. SAMPLE POPULATION Unpaired cadaveric canine forelimbs (n = 17). METHODS In a servohydraulic testing frame, thin-film pressure sensors were placed into the lateral and medial compartments of the elbow. Specimens were tested in 135° of elbow joint flexion at 200 N of cyclic axial force, followed by a 20 seconds hold. Intra-articular contact area (CA), mean contact pressure (mCP) and peak contact pressure (pCP) were measured in each compartment. After radial shortening, testing was repeated and limbs randomized into proximal ulnar ostectomy with IM pin (PUO) or sequential distal ulnar ostectomy (DUO), interosseous ligament release (DUO-L), and ulnar attachment of the abductor pollicis longus muscle and interosseous membrane release (DUO-ML). Paired t-tests were used to compare each treatment to baseline values. Differences between treatment groups were evaluated with a mixed model with random effect to adjust for the clustering of limbs within dog. P < .05 was considered significant. RESULTS Radial shortening resulted in shift of mCP and pCP from the lateral to the medial compartment. The PUO group resulted in normalization of medial compartment mCP and decrease of pCP, whereas in the DUO group return to baseline was achieved only after DUO-ML. CONCLUSION PUO is effective in unloading medial compartment pCP in an incongruent joint.