Transpalpebral ultrasonographic measurement of the optic nerve sheath diameter in healthy dogs.

OBJECTIVE: To develop a reference range for ultrasonographically measured optic nerve sheath diameter (ONSD-US) in dogs. We hypothesized that ONSD-US can be measured reliably and is associated with weight but not age, sex, or body condition score (BCS), and that the relationship between weight and ONSD-US in dogs is allometric due to canine size variations. DESIGN: Prospective, observational study. SETTING: University teaching hospital. ANIMALS: Seventy-eight healthy adult dogs. INTERVENTIONS: The ONSD was measured by a standardized transpalpebral approach. MEASUREMENTS AND MAIN RESULTS: Regression analysis showed the relationship between weight and ONSD was better fit with a linear model (R2 = 0.8510) than an allometric model (R2 = 0.7917). Multiple regression analysis showed ONSD is associated with weight (P < 0.0001), age (P = 0.0021), and BCS (P = 0.0007), but not with sex. Dominance analysis showed 94.6% of the variance explained by the model was due to weight. Intraclass correlation coefficient (ICC) analysis showed excellent interobserver (ICC = 0.9338-0.9608) and intraobserver (ICC = 0.9893) reliability. CONCLUSIONS: These results suggest that ONSD-US may be reliably measured in dogs using our described transpalpebral approach, and we have calculated prediction intervals based on body weight. Future studies are needed to determine if ONSD-US measurements are associated with intracranial hypertension as shown in human medicine.

Effect of the Proximal Abducting Ulnar Osteotomy on Intra-Articular Pressure Distribution and Contact Mechanics of Congruent and Incongruent Canine Elbows Ex Vivo.

OBJECTIVE: To determine the effects of the Proximal Abducting Ulnar Osteotomy (PAUL) on contact pressures of congruent and incongruent (short radius) canine elbows. STUDY DESIGN: Ex vivo biomechanical study. SAMPLE POPULATION: Unpaired normal cadaveric canine forelimbs (n=16). METHODS: A servohydraulic testing frame and thin-film sensors were utilized to measure intra-articular contact area (CA), mean contact pressure (mCP), and peak contact pressure (pCP) for medial and lateral elbow compartments. Percent contribution of the medial compartment relative to the whole (%Med) was also examined. Baseline data were collected in 9 congruent elbows and 7 incongruent elbows where the radius was shortened. Both sets of elbows were tested following ulnar osteotomy and sequential placement of 2 and 3 mm PAUL plates and paw repositioning (to account for any medial to lateral shift of transarticular forces). Paired t-tests compared sequential procedural steps. P<.05 was significant. RESULTS: For congruent elbows, the 2 mm PAUL plate decreased CA in both compartments compared to baseline; lateral pCP increased with subsequent paw repositioning. Induction of radio-ulnar incongruity decreased CA and increased mCP medially, decreased pCP laterally, and increased %MedCA and %MedmCP compared to baseline. Both PAUL plates decreased mCP and pCP medially, with no effect laterally. Paw repositioning had no effect. CONCLUSION: The PAUL procedure had no effect on medial compartment pressure in the congruent elbow. It may ameliorate increased medial compartment pressure in the incongruent elbow. This change does not result from a medial to lateral compartmental shift and deserves further investigation.

CORRELATIONS AMONG ULTRASONOGRAPHIC MEASUREMENTS OF OPTIC NERVE SHEATH DIAMETER, AGE, AND BODY WEIGHT IN CLINICALLY NORMAL HORSES.

Early diagnosis of high intracranial pressure (ICP) is critical for minimizing progressive brain injury due to reduced cerebral perfusion. In people, detecting enlargement of the optic nerve sheath diameter (ONSD) by transpalpebral ultrasonography has been found to be an accurate test for high ICP. Aims of this prospective, observational, cross-sectional study were to test hypotheses that (1) ultrasonographic measurement of ONSD would be repeatable in horses, (2) have acceptable interobserver agreement, and (3) would be correlated with age and body weight. The sample population included 48 horses without clinical signs of high ICP and with varying ages and body weights. Two observers independently performed ONSD measurements in both eyes. All measurements ranged from 2.6 to 6.5 mm. The mean difference of repeated measures within observers was ≤0.1 mm and the coefficients of variation ranged from 5.0% to 8.8%. The mean difference of measures between observers was ≤0.2 mm. After correcting for performing multiple tests, no significant rank correlation (all r < 0.4 [absolute value]) was detected between ONSD and age or body weight. However, we observed smaller ONSD in foals versus adults (all P ≤ 0.002). In the foals, all observed measures of rostrocaudal and dorsoventral ONSD were <5 mm. In the adults, all observed measures of rostrocaudal and dorsoventral ONSD were ≤6.5 mm. Findings indicated that ultrasonographic ONSD measurement is a feasible test for use in horses of varying ages and sizes. Further investigation of this ultrasonographic measure as a clinical test for horse with suspected high ICP is warranted.

Diagnosis and treatment of mesenteric volvulus in a red kangaroo (Macropus rufus).

CASE DESCRIPTION: An 8-year-old male red kangaroo (Macropus rufus) was evaluated with a 2-week history of vomiting and anorexia. Four days prior, the patient became refractory to medical management. The kangaroo was admitted for diagnostic testing and treatment including whole body CT, blood work, and emergency laparotomy. CLINICAL FINDINGS: CT findings of a severely enlarged stomach, splenic displacement, and a whirl sign were indicative of mesenteric volvulus with gastric dilatation-volvulus (GDV). Contrast enhancement of abdominal viscera suggested intact arterial blood supply; however, compression of the caudal vena cava and portal vein indicated venous obstruction. Results of preoperative blood work suggested biliary stasis without evidence of inflammation. Additionally, a tooth root abscess was diagnosed on the basis of results of CT. TREATMENT AND OUTCOME: Exploratory laparotomy confirmed the diagnosis of mesenteric volvulus and GDV. The volvuli were corrected by clockwise derotation, and a gastropexy was performed. Tissue samples were obtained from the spleen and liver for evaluation. The kangaroo recovered from surgery, and the abscessed tooth was extracted 6 days later. Eight days after initial evaluation, the kangaroo was discharged. CLINICAL RELEVANCE: In the present report, the CT whirl sign was used to diagnose volvulus of the abdominal viscera, which suggests that this diagnostic indicator has utility in veterinary patients. Mesenteric volvulus with GDV was successfully treated in a nondomestic species. The tooth root abscess, a common condition in macropods, may explain the historic episodes of anorexia reported by the owner and may have contributed to the development of mesenteric volvulus and GDV in this kangaroo.

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.

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.

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.

Comparison of TPA, 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.

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.

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.

Imaging diagnosis--equine nasal septal thickening due to chronic chondritis.

We describe the use of computed tomography (CT) in a 6-year-old mare with upper airway obstruction due to an abnormally thick nasal septum. Upon CT imaging, multifocal, expansile cyst-like lesions were detected in the nasal septum. The histopathologic diagnosis was chronic dissecting chondritis. Resection of the abnormal nasal septum resulted in resolution of the clinical signs.

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.

Endobronchial polyp derived from a myxosarcoma in the lung of a dog.

An endobronchial polyp was visible radiographically and bronchoscopically in an 11-year-old, mixed-breed dog with a persistent cough. The polyp was removed by traction. Initial histological examination suggested it was a myxomatous fibroma. The cough resolved but recurred with polyp regrowth. Two additional lung masses became visible radiographically. The polyp was removed twice more at 6-month intervals. Euthanasia was performed 15 months after first presentation when coughing recurred soon after the final bronchoscopy. Histological examination revealed that the mass was a myxomatous sarcoma. The lung contained two other unrelated tumors: a bronchioloalveolar carcinoma and a carcinoma of unknown origin.

Relation between age, body weight, and medial retropharyngeal lymph node size in apparently healthy dogs.

The aims of this study were to determine the size of the medial retropharyngeal lymph nodes in apparently healthy dogs using ultrasonography and to investigate relationships between body weight (1.8-59 kg), age (1.0-15 years), and medial retropharyngeal lymph node sizes (width, height, and length). The sample population consisted of 100 apparently healthy, volunteered, adult dogs. The data were normally distributed, thus mean, SD, and Pearson's correlation were used. Repeatability of ultrasound measures was assessed as the percentage of differences between duplicate measures that were within 2 SDs of the differences: all measures were at least 93% repeatable (differences typically were < or = 0.25 cm and always < 1 cm). No difference between sexes was observed. The medial retropharyngeal lymph node increased in size with increased body weight (r = 0.46 to 0.59) and decreased in size with increased age (r = -0.30 to -0.50). Although statistically significant, the actual variation is not likely clinically important due to the small range of sizes, measurement error, and various combinations of age and body weight. Therefore, regardless of body weight or age, the average width is 1.0 cm, height is 0.5 cm, and length is 2.5 cm and maximum width is 2 cm, height is 1 cm, and length is 5 cm. Based on the maximal difference between duplicate measures (with some exception), any change > or = 0.4 cm with width or height, or > or = 1.0 cm in length, in a follow up measurement probably represents a true biological change rather than measurement error.

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

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.