ENDOSCOPIC ULTRASONOGRAPHY OF THE PANCREAS IN THE DOG

Endoscopic ultrasonography was done in 12 normal adult dogs to investigate its efficacy in visualization of the pancreas. The endoscopic ultrasonographic device used in the present study had a curved-array ultrasound transducer mounted in front of the objective lens. The tip of the ultrasonic endoscope was inserted into the stomach, and all examinations of the pancreas were performed from within the stomach. Endoscopic ultrasonography provided good images of most parts of the pancreas except for the ends of each lobe. Useful information about the pancreatic parenchyma, including pancreatic lobular structure, pancreatic duct, and vessels of the pancreas was obtained by endoscopic ultrasonography. Blood flow within vessels was detected using color Doppler and pulsed-wave Doppler examination. These results suggest that endoscopic ultrasonography is available as an effective diagnostic modality in small animal practice.     

CONTRAST‐ENHANCED HARMONIC ULTRASONOGRAPHY OF MEDIAL ILIAC LYMPH NODES IN HEALTHY DOGS

Herein, we describe the normal contrast‐enhanced harmonic, color, and power Doppler ultrasonographic characteristics of the medial iliac lymph nodes in healthy dogs. Contrast‐enhanced harmonic ultrasonography of the medial iliac lymph nodes was performed on 14 healthy dogs after intravenous administration of the lipoprotein‐bound inert gas‐filled microbubble contrast media Definity^®. Time–pixel intensity curves were generated for 1‐min postinjection. Quantification of these curves was performed using Philips QLab software. Non‐contrast‐enhanced power and color Doppler examinations were performed in each node to assess vascular patterns subjectively. Normal lymph nodes exhibited a mean contrast wash‐in phase beginning at 6.3 s from the time of injection with mean peak pixel intensity at 12.1 s. Angioarchitecture was best visualized with contrast‐enhanced harmonic ultrasound compared with power and color Doppler. Normal lymph nodes in dogs have a central artery with a centrifugal and uniform branching pattern. Contrast‐enhanced harmonic ultrasonography is a noninvasive examination that demonstrates improved visibility of the intranodal architecture of healthy medial iliac lymph nodes in dogs compared with conventional, non‐contrast‐enhanced Doppler methods that may have future clinical applications.     

NON-INVASIVE DIAGNOSIS OF ISCHEMIC BRAIN DAMAGE AFTER CARDIOPULMONARY RESUSCITATION IN DOGS BY USING TRANSCRANIAL DOPPLER ULTRASONOGRAPHY

We have attempted to identify whether it is possible to utilize transcranial Doppler ultrasonography to evaluate the brain damage that occurs after resuscitation from 3 min (control group) and 12 min (damage group) of cardiac arrest in dogs. In this study we used transcranial Doppler ultrasonography to follow the basilar arterial flow and middle cerebral arterial flow for 180 min following the induction of cardiac arrests. Two abnormal waveform patterns (the "to-and-fro" and "diastolic no-flow" patterns) were found in all dogs in the damage group whereas abnormal waveforms were not detected in the control group. Pathological diagnosis revealed that, compared with the control group, the damage group recognized ischemic alteration at the level of the hippocampus and caudate nucleus. In conclusion, this study shows that the basilar arterial flow of observed with transcranial Doppler ultrasonography may be use for the prediction of outcome and the diagnosis of brain damage in the dog.     

ULTRASONOGRAPHIC DIAGNOSIS OF CONGENITAL PORTOSYSTEMIC SHUNTS IN DOGS: RESULTS OF A PROSPECTIVE STUDY

The aims of this study were to determine if accurate diagnosis of congenital portosystemic shunt was possible using two dimensional, grey-scale ultrasonography, duplex-Doppler, and color-flow Doppler ultrasonography in combination, and to determine if dogs with congenital portosystemic shunts have increased or variable mean portal blood flow velocity. Eighty-two dogs with clinical and/or clinicopathologic signs compatible with portosystemic shunting were examined prospectively. Diagnosis of congenital portosystemic shunt was subsequently confirmed in 38 of these dogs using operative mesenteric portography: 14(37%) dogs had an intrahepatic shunt and 24(63%) had an extrahepatic shunt. Ultrasonography had a sensitivity of 95%, specificity of 98%, and accuracy of 94%. Ultrasonographic signs in dogs with congenital portosystemic shunts included small liver, reduced visibility of intrahepatic portal vessels, and anomalous blood vessel draining into the caudal vena cava. Correct determination of intra - versus extrahepatic shunt was made ultrasonographically in 35/38 (92%) dogs. Increased and/or variable portal blood flow velocity was present in 21/30 (70%) dogs with congenital portosystemic shunts. In one dog with an intrahepatic shunt the ultrasonographic diagnosis was based partly on finding increased mean portal blood flow velocity because the shunting vessel was not visible. Detection of the shunting vessel and placement of duplex-Doppler sample volumes were facilitated by use of color-flow Doppler. Two-dimensional, grey-scale ultrasonography alone is sufficient to detect most intrahepatic and extrahepatic shunts; sensitivity is increased by additional use of duplex-Doppler and color-flow Doppler. Increased and/or variable portal blood flow velocity occurs in the majority of dogs with congenital portosystemic shunts.     

COLOR FLOW DOPPLER IMAGING AND DOPPLER SPECTRAL ANALYSIS OF THE BRAIN OF NEONATAL DOGS

Doppler ultrasonography was performed on the cerebral arteries o f 19 neontal dogs.Vascular structures were identified using anatomic preparations of brains pre-injected with a radiopaque silicone rubber product and cleared using a modified tissue clearing technique. Brain sections were subsequently radiographed of examined under a steromicroscope. Color flow Doppler imagin was used to facilitate positioning of the Doppler calipers for measurement of peak systolic velocity, minimum diastolic velocity, and resistance index. Blood flow velocities in the internal carotid and middle cerebral arteries were lower when measured intransvere images than in sagittal images. The rostral cerebral arteries could be measured using either plane but values obtained from different locations or using different methods of measurement were statistically different. Blood flow velocities generally increased during the first month after birth. Arterial signals were diphasic with flow throughout diastole. Resistance indices most often were between 0.6 and 0.7 and did not exceed 0.86.     

Use of color doppler imaging for determining the resistive index of the medial long posterior ciliary artery in clinically normal conscious dogs

OBJECTIVE: To evaluate the use of color Doppler imaging (CDI) for determining the resistive index (RI) of the medial long posterior ciliary artery (mLPCA) in clinically normal conscious dogs. ANIMALS: 18 (10 sexually intact males, 8 sexually intact females) dogs between 1 and 5 years old. PROCEDURE: Color Doppler ultrasonography was performed on both eyes with dogs in a sitting position. Each eye was imaged from the region dorsal to the zygomatic arch with the transducer positioned in a horizontal plane. The mLPCA was localized, and RI was calculated from velocities obtained for 3 similar Doppler waveforms. To determine the reproducibility of CDI-derived RI, measurements were repeated twice at a 10-day interval. RESULTS: Mean (+/- SD) RI of the mLPCA was 0.68 +/- 0.07 (95% confidence interval, 0.65 to 0.70; n = 36 eyes). Resistive index did not significantly differ between right and left eyes or male and female dogs. In addition, body weight was not correlated with RI. Repeated measurements of RI did not yield significantly different results (interclass correlation coefficient, 0.8297). CONCLUSION AND CLINICAL RELEVANCE: Color Doppler imaging appears to be a valid technique for determination of RI of the mLPCA in conscious dogs. This technique may be useful for investigating the pathophysiologic processes of many ocular and orbital vascular disorders in dogs.     

SMOOTH MUSCLE NEOPLASIA OF THE URINARY BLADDER WALL IN THREE DOGS

Smooth muscle origin neoplasia of the urinary bladder wall is rare in dogs. This report describes the ultrasonographic features of two bladder wall leiomyomas and one bladder wall leiomyosarcoma. All three dogs had a single, smoothly marginated, round, hypo to mixed echogenicity intraluminal mass in the urinary bladder. Based on color Doppler examination of the masses, there was no visible blood flow.     

Spontaneous reduction of intestinal intussusception in five young dogs

Five, 3- to 8-month-old dogs had clinical and ultrasonographic findings consistent with intestinal intussusception, but findings were negative on exploratory celiotomy. Ultrasonography had revealed a target-like mass (median maximal diameter 25 mm) on transverse section and multiple hyperechoic or hypoechoic parallel lines (median length 36.8 mm) on longitudinal section. Blood flow in the intussuscepted bowel was detected in most of the cases. In dogs with similar findings, the authors recommend ultrasonographic reexamination of the abdomen after general anesthesia (but before surgery) to exclude spontaneous reduction of the intussusception.     

ULTRASONOGRAPHY OF THE SOLAR ASPECT OF THE DISTAL PHALANX IN THE HORSE

Ultrasonographic examinations were performed on the solar aspect of the distal phalanx of 10 feet of five normal live horses (Group 1), 22 feet of seven normal cadavers (Group 2), and nine feet of five horses with pathology of the dorsal solar aspect of the distal phalanx (Group 3). Lateromedial radiographs of the distal phalanx were made in all groups, and in Group 2, digits were sagitally sectioned after imaging. The ultrasonographic and radiographic appearance of the sagittal solar aspect of the distal phalanx was described. Measurements of the distance between the sole and the distal tip of the distal phalanx (A), the solar aspect of the apex of the frog and the distal phalanx (B), and the body of the frog's surface and flexor surface of the distal sesamoid bone (C) were made ultrasonographically, radiographically, and on the sectioned cadaver specimens. There was no statistical difference between the radiographic, ultrasonographic, and direct cadaver measurements in A and C. In B, there was a statistical difference between the radiographic, ultrasonographic, and cadaver measurements-most likely as a result of the difference in trimming of the frog apex. Ultrasonographic and radiographic examination of the nine feet of the five horses in Group 3 were performed and the abnormalities described. Color flow and power Doppler ultrasonography were performed on the normal sagittal solar distal phalanx, on the impar distal sesamoidean ligament, and at the insertion of the deep digital flexor tendon on the facies flexoria of the distal phalanx. Power Doppler in these horses showed blood flow at 0.16-0.48 kHz at the tip of the distal phalanx and at 0.16 kHz at the deep digital flexor tendon insertion and in the impar distal sesamoidean ligament. Using color flow Doppler in normal horses mean blood flows ranged from 1.8 to 5.4 cm/s at the tip of the distal phalanx and 1.8-2.0 cm/s at the deep digital flexor tendon insertion and in the impar distal sesamoidean ligament.     

ECHO-DOPPLER FINDINGS OF A CAROTID-JUGULAR FISTULA IN A FOAL

A seven-month-old male Standardbred was referred with a 4-month history of left jugular groove distension. On physical examination severely dilated left maxillary, linguofacial and jugular veins were appreciable. Blood gas analysis results indicated higher degree of oxygenation in the left jugular vein. Bi-directional flow signals, with normal systolic and early diastolic flow, and late diastolic retrograde flow, were noted on pulsed-wave Doppler interrogation and color flow mapping of the left jugular blood flow. A systolic-diastolic signal with spectral broadening was detected when positioning the sample gate near the internal jugular wall, in the distal left cervical region. Color Doppler imaging of the same region showed blood flow passage between the left common carotid artery and the left jugular vein through a small carotid-jugular fistula. Markedly increased blood flow velocities and volumetric flow, and decreased resistive index were recorded in the left compared to the right common carotid artery.     

B-MODE AND DOPPLER ULTRASOUND IMAGING OF THE SPLEEN WITH CANINE SPLENIC TORSION: A RETROSPECTIVE EVALUATION

The ultrasonographic appearance of splenic torsion has been described; the splenic parenchyma can be normal, hypoechoic or anechoic with interspersed linear echoes (coarse/"lacy" appearance). The ultrasonographic parenchymal appearance of 15 dogs in this report with splenic torsion varied: mottled hypoechoic regions (n=2), diffusely hypoechoic (n=11) and normal (n=2). Because splenic torsion causes vascular congestion due to splenic vein compression and eventual thrombosis, visible splenic vein intraluminal echogenicities compatible with thrombi were seen in 13 dogs using B-mode. Using spectral Doppler and color Doppler imaging of the splenic veins, no measurable flow velocities were detected in any of the 15 dogs. The varied B-mode ultrasonographic appearance of the splenic veins for intraluminal echoes and spectral or color Doppler evaluation for absent velocity flow.     

POWER DOPPLER ASSESSMENT OF THE NEOVASCULARIZATION DURING UNCOMPLICATED FRACTURE HEALING OF LONG BONES IN DOGS AND CATS

The aims of this prospective study were to test the feasibility of assessing neovascularization with power Doppler ultrasonography and to investigate its usefulness to follow fracture healing of long bones in dogs and cats. A total of 51 patients (44 dogs and seven cats) were followed. Fracture types differed from simple to comminuted. Therapy ranged from external coaptation to plate osteosynthesis. Patients were followed with radiography, B-mode real time and power Doppler ultrasonography every 2-4 weeks until the fracture was healed. All fractures healed uneventfully. A semi-quantitative numerical score based on signal intensity, vessel area, and number of Doppler signals was assigned and the mean value was used to compare patients and examinations. Time postoperatively was divided into periods of 10 days. No Doppler signal was present during the first 10 days. The mean of the scores was highest between 11 and 20 days postoperatively and the median of the scores peaked between 21 and 30 days. A gradual decrease was seen thereafter. The mean of the scores was zero at 71-80 days and the median at 51-0 days postoperatively for the grouped results. In all positive power Doppler examinations, signals were present in and close to the callus. In seven patients (five dogs and two cats) signals were also present in the peripheral soft tissues in one of the follow up examinations. The normal healing process of fractured bones can be visualized using power Doppler ultrasonography and follows a distinctive time-dependent pattern.     

COMPARISON OF THREE METHODS FOR CALCULATING PORTAL BLOOD FLOW VELOCITY IN DOGS USING DUPLEX-DOPPLER ULTRASONOGRAPHY

Measurement of portal blood flow in dogs using duplex-Doppler ultrasonography has potential clinical utility for diagnosis of cirrhosis and portosystemic shunts. Three methods for calculating portal blood flow were compared to identify a consistent method with minimal potential for intraoperator variation. Sixteen unsedated, normal beagles had their mean portal blood flow velocity determined using three methods: method 1 used a small Doppler sample volume positioned over the center of the portal vein and manual selection of data points on the resulting velocity spectra, followed by arithmetic correction of the calculated maximum velocity to mean velocity using the factor 0.57; method 2 used a small centrally-located Doppler sample volume and computed maximum flow determination, again corrected using the factor 0.57; method 3 used a large Doppler sample volume that overlapped the walls of the portal vein followed by computed mean blood flow velocity determination. The calculated mean (SD) portal blood flow velocity was 15.8 (1.8), 15.1 (1.4), and 14.7 (2.5) cm/s using methods 1–3, respectively. There was no significant difference between the results of the three methods; however, method 3 (uniform insonation) was easier to use and produced a higher amplitude Doppler signal and therefore represents a useful alternative to the peak flow methods.     

LAPAROSCOPIC ULTRASONOGRAPHY IN SIX DOGS

The aim of this study was to describe the technique of laparoscopic ultrasonography in six dogs with intra-abdominal disease. Investigation of the abdominal cavity was undertaken initially in each dog by laparoscopy alone. After exploration and visualization of a diseased organ, a 7.5 MHz microconvex ultrasound probe was introduced into the abdomen through a laparoscopic cannula for videoguided ultrasound examination. Laparoscopic ultrasonography allows core biopsy or needle aspiration to be performed by guiding the needle into nonsuperficial lesions, where videoendoscopic guidance alone is not enough. In addition, color Doppler ultrasonography is useful to examine the vascular pattern to minimize or eliminate complications when a biopsy is performed.     

DIAGNOSIS OF URINARY TRACT OBSTRUCTION IN DOGS USING DUPLEX DOPPLER ULTRASONOGRAPHY

The ability of duplex Doppler ultrasonography to assist with the diagnosis of urinary tract obstruction was investigated in a study of 5 dogs with surgically induced, unilateral ureteral obstruction. The resistive index (RI) of obstructed kidneys was compared to that of controls and to the contralateral unobstructed kidneys. The RI was also evaluated following relief of obstruction. On the basis of an RI measurement ≥0.70 indicating obstruction, a sensitivity of 73% and a specificity of 77% was determined for the diagnosis of obstruction with Doppler ultrasonography. Although mean RI was elevated in obstructed kidneys compared to controls, it was concluded that a high false-negative rate (27%) limits the clinical usefulness of Doppler ultrasonography for the detection of urinary obstruction in dogs. The RI difference between obstructed and nonobstructed kidneys was also evaluated within individual animals, but the magnitude of difference between kidneys did not significantly improve the detection rate for obstruction.     

EFFECTS OF EXPERIMENTAL NERVE ROOT COMPRESSION ON ARTERIAL BLOOD FLOW VELOCITY IN THE SEVENTH LUMBAR SPINAL GANGLION OF THE DOG: MEASUREMENT USING INTRAOPERATIVE DOPPLER ULTRASONOGRAPHY

Intraoperative Doppler ultrasonography was used to measure the effects of four experimental nerve root compression treatments (central compression, central-plus-lateral compression, lateral compression, and compression release) on arterial blood flow velocities in the seventh lumbar spinal ganglion of three dogs. Graphed blood flow velocity changes (change = treatment value − pretreatment value) were below baseline during the first three compression treatments and above baseline following compression release. Mean blood flow velocity changes for both central-plus-lateral compression and lateral compression differed (p ≤ 0.05) from changes for central compression. Changes for central-plus-lateral compression did not differ (p > 0.05) from changes for lateral compression. Changes among the first three compression treatments differed (p ≤ 0.05) from changes for compression release. No histologic abnormalities were identified in compressed nerve tissues, compared to contralateral controls. These findings indicate that stenosis within the L7-S1 intervertebral foramen may cause ischemia of the L7 spinal ganglion in dogs.     

Comparison of B-mode and Doppler ultrasonographic findings with histologic features of benign and malignant superficial lymph nodes in dogs

OBJECTIVE: To compare and correlate B-mode and color Doppler ultrasonographic characteristics with histopathologic findings of benign and malignant superficial lymph nodes in dogs. STUDY POPULATION: 50 superficial lymph nodes that were normal, abnormally large on physical examination, or represented regional lymph nodes draining an area of suspected primary malignancy in 30 dogs. PROCEDURES: Before excision, lymph nodes were evaluated via B-mode and color Doppler ultrasonography to assess size, echogenicity, presence of a hilus, acoustic transmission, and vascular flow. Formalin-fixed, paraffin-embedded tissue sections of excised lymph nodes were stained with H&E and examined for the presence and extent of necrosis, fibrosis, fat, metastases, and tissue heterogeneity. To assess vascularity, the number and distribution of vessels stained by the Verhoeff van Gieson technique were recorded. RESULTS: In superficial lymph nodes, a varied echogenicity corresponded to tissue heterogeneity. The ultrasonographic detection of a hilus was associated with the presence of fibrous tissue, fat, or both in the hilar region. Acoustic enhancement corresponded to presence of areas of intranodal necrosis. There was significant correlation between both the distribution and the number of vessels detected via ultrasonography and that detected by histopathology. The amount of flow estimated via ultrasonography was typically higher than that estimated via histologic examination. CONCLUSIONS AND CLINICAL RELEVANCE: Results indicated that histopathologic changes in canine lymph nodes have associated ultrasonographic changes and suggest that lymph node ultrasonography has an important role in the evaluation of lymph nodes in dogs in general and in dogs with neoplastic disease in particular.     

ULTRASONOGRAPHIC DIAGNOSIS OF PERSISTENT HYPERPLASTIC TUNICA VASCULOSA LENTIS/PERSISTENT HYPERPLASTIC PRIMARY VITREOUS IN TWO DOGS

Ultrasonography was performed on a Basset hound and a Doberman clinically suspected of persistent hyperplastic tunica vasculosa lentis/persistent hyperplastic primary vitreous. In both dogs, hyperechoic lenses with a triangular-shaped echodense structure retrolentally were visible, and a very thin hyperechoic strand was seen penetrating the anechoic vitreous from this retrolental tissue to the area of the optic nerve. Using color Doppler imaging, blood flow was evident in parts of the retina in both dogs. With power Doppler imaging there was blood flow in the lens and hyperechoic strand of the Basset hound on the first examination; whereas, on re-examination 5 months later, this was not found. Other abnormalities, such as retinal detachment, endophthalmitis, vitreous hemorrhage, microphthalmia, and posterior neoplasia could be excluded.     

CHARACTERIZATION OF CANINE SUPERFICIAL TUMORS USING GRAY-SCALE B MODE, COLOR FLOW MAPPING, AND SPECTRAL DOPPLER ULTRASONOGRAPHY—A MULTIVARIATE STUDY

Superficial tumors are not routinely evaluated by two- or three-dimensional diagnostic imaging methods as part of the staging of canine cancer patients, although superficial tumors are readily imaged by ultrasound. The objectives of this study were to characterize the ultrasonographic patterns of superficial tumors and to evaluate whether ultrasound can help discriminate between benign and malignant tumors in dogs. Superficial tumors (n=132) in 86 dogs were evaluated by B mode, color flow mapping, and spectral Doppler ultrasonography. Size, echogenicity, tumor border definition, invasiveness, acoustic transmission, presence and distribution of vascular flow to and within the tumor, as well as perfusion indices were measured. The tumors were classified as lipomas, benign tumors, atypical mammary tumors, and malignant tumors. Multivariate statistics using discriminant analysis was used to determine which parameters may be used to predict the status of the tumor. Tumor echogenicity, border shape, acoustic shadowing, total number of vessels to the tumor and the total flow amount are the parameters that in combination resulted in the lowest classification error (24%), meaning that on average three out of four tumors were correctly classified using these parameters. All the lipomas and atypical mammary tumors were classified correctly by ultrasonography. The results of this study show that ultrasonography has an important role in the evaluation of canine superficial tumors, particularly in the evaluation of tissue homogeneity and tumor vascularity.     

DIASTOLIC MITRAL REGURGITATION DETECTED BY PULSED WAVE DOPPLER ECHOCARDIOGRAPHY AND COLOR FLOW DOPPLER MAPPING IN FIVE DOGS AND TWO CATS WITH SECOND- AND THIRD-DEGREE ATRIOVENTRICULAR BLOCK

M-mode echocardiography, color flow Doppler mapping, and pulsed wave Doppler echocardiography were used to characterize diastolic mitral regurgitation in five dogs and two cats with second- and third-degree atrioventricular block. Incomplete closure and partial reopening of the mitral valve following nonconducted P-waves were demonstrated by m-mode echocardiography. Low velocity reflux of blood into the left atrium after nonconducted P-waves was imaged by color-flow Doppler mapping and spectral Doppler echocardiography. Late diastolic mitral regurgitation was not observed in clinically normal control dogs or cats, but a low velocity, mid-diastolic flow reversal was detected in the dogs. This probably represented normal physiologic intravalvular flow. Diastolic mitral regurgitation is a common echocardiographic finding, in dogs and cats with, second- and third-degree atrioventricular block.