SUPERPARAMAGNETIC IRON OXIDE-ENHANCED MAGNETIC RESONANCE IMAGING OF THE LIVER IN BEAGLE DOGS

The role of superparamagnetic iron oxide as a tissue-specific contrast medium has been established in humans, especially for hepatic imaging. Superparamagnetic iron oxide particles exhibit a tissue-specific biodistribution to the reticuloendothelial system, where they predominantly shorten transverse T2 relaxation time. Most hepatic tumors lack Kupffer cells; therefore, the T2 of tumors remains virtually unchanged after administration of superparamagnetic iron oxide. The resulting loss of signal intensity from the liver, with unchanged tumor signal intensity, increases lesion-to-liver contrast. In this study, MR images were acquired with fast gradient echo recalled at steady state (FGRE) in five Beagle dogs before and after injection of superparamagnetic iron oxide. The effect of superparamagnetic iron oxide on signal intensity of the liver with time was assessed. A signal intensity decrease of 65.7+/-10.0% was detected at 20 minutes, and it continued to decrease until the last time point of MR scanning (200 minutes). The liver intensity of all dogs dropped to half its value after 20 minutes. The effect of motion was minimized by breath holding. Superparamagnetic iron oxide did not have any adverse effects on the dogs.     

EFFECTS OF INTRAVENOUS DEXMEDETOMIDINE ON CARDIAC CHARACTERISTICS MEASURED USING RADIOGRAPHY AND ECHOCARDIOGRAPHY IN SIX HEALTHY DOGS

Dexmedetomidine is a highly specific and selective α2‐adrenergic receptor agonist widely used in dogs for sedation or analgesia. We hypothesized that dexmedetomidine may cause significant changes in radiographic and echocardiographic measurements. The objective of this prospective cross‐sectional study was to test this hypothesis in a sample of six healthy dogs. Staff‐owned dogs were recruited and received a single dose of dexmedetomidine 250 μg/m² intravenously. Thoracic radiography and echocardiography were performed 1 h before treatment, and repeated 10 and 30 min after treatment, respectively. One observer recorded cardiac measurements from radiographs and another observer recorded echocardiographic measurements. Vertebral heart score and cardiac size to thorax ratio on the ventrodorsal projection increased from 9.8 ± 0.6 v to 10.3 ± 0.7 v (P = 0.0007) and 0.61 ± 0.04 to 0.68 ± 0.03 (P = 0.0109), respectively. E point‐to‐septal separation and left ventricle internal diameter in diastole and systole increased from 2.4 ± 1.1 to 6.6 ± 1.9 mm, 32.3 ± 8.1 to 35.5 ± 8.8 mm, and 19.4 ± 6 to 27.0 ± 7.2 mm, respectively (P < 0.05). Fractional shortening and sphericity index decreased from 40.7 ± 5.8 to 24.4 ± 2.9%, and 1.81 ± 0.07 to 1.58 ± 0.04, respectively (P < 0.05). Moderate‐to‐severe mitral regurgitation and mild pulmonic regurgitation occurred in all dogs after dexmedetomidine administration. Findings indicated that dexmedetomidine could cause false‐positive diagnoses of valvular regurgitation and cardiomegaly in dogs undergoing thoracic radiography and echocardiography.     

DIAGNOSTIC ACCURACY OF GRAY‐SCALE ULTRASONOGRAPHY FOR THE DETECTION OF HEPATIC AND SPLENIC LYMPHOMA IN DOGS

Gray‐scale ultrasonography is often used to screen for involvement of the liver and spleen in canine lymphoma patients but the utility of sonography for staging lymphoma has not been evaluated quantitatively. We performed abdominal sonography in 28 dogs with a confirmed diagnosis of lymphoma. Needle aspirates were obtained for cytology from three separate sites in the liver and three sites in the spleen and the sonographic appearance was noted at each site. Our hypothesis was that in dogs newly diagnosed with lymphoma, abnormal appearance of the liver or spleen on ultrasound examination is an indication that lymphoma is present in that organ. Cytologic evaluation was used as the gold standard. The sensitivity, specificity, positive predictive value, negative predictive value, and accuracy of hepatic and splenic abnormalities seen on ultrasound for diagnosis of lymphoma were 72.7%, 80.6%, 77.4%, 76.3%, and 76.8% for the liver, respectively, and 100%, 23.3%, 64.6%, 100%, and 68.1% for the spleen, respectively. Based on these results, we recommend that aspirates be performed for detection of lymphoma in the spleen of dogs only when the spleen appears abnormal ultrasonographically and that cytology of the liver be performed, regardless of ultrasonographic appearance, to determine the presence or absence of lymphoma.     

HEPATIC ABSCESSES IN 13 DOGS: A REVIEW OF THE ULTRASONOGRAPHIC FINDINGS, CLINICAL DATA AND THERAPEUTIC OPTIONS

Historical, physical examination, clinicopathologic, radiographic and ultrasonographic findings of 13 dogs with hepatic abscesses were reviewed. Liver abscessation was characterized by number, size, shape, echogenicity and location. Solitary lesions greater than 3 cm were more common than multiple ones. The abscesses were mainly poorly echogenic lesions, often with central cavitation. The shape of the lesion ranged from round to oval or irregular. Enhancement artifact, abdominal effusion, regional lymphadenopathy and hyperechoic perihepatic fat, were identified in several dogs. Ultrasound-guided aspiration was performed in 10 of 13 dogs, and confirmed abscessation with cytologic and microbiologic evaluation. Ultrasound-guided percutaneous drainage of abscesses was performed as an adjunct to medical management in four dogs.     

ULTRASONOGRAPHIC ELASTOGRAPHY OF THE LIVER,SPLEEN, KIDNEYS,AND PROSTATE IN CLINICALLY NORMAL BEAGLE DOGS

Standard ultrasonography is often insensitive for distinguishing normal vs. diseased states for canine abdominal organs. Ultrasonographic elastography is a new technique that is becoming increasingly available and may help to improve sensitivity. This study evaluated the feasibility, repeatability, and reproducibility of strain elastography of the liver, spleen, kidneys, and prostate in healthy dogs and described the elasticity of each organ using strain values and strain ratios. The reproducibility of strain elastography was excellent, and intraobserver repeatability was moderate to excellent. The strain value of each organ was not significantly different among dogs (liver = 143.38 ± 7.41, spleen = 141.04 ± 9.03, left renal cortex = 141.26 ± 7.50, right renal cortex = 145.80 ± 7.79, and prostate = 135.46 ± 5.80), except for the renal medulla (left = 51.19 ± 4.54 and right = 51.93 ± 5.09) (P < 0.05). The strain ratios for the liver, spleen, renal cortex, and prostate were similar with no significant difference (liver = 10.20 ± 1.47, spleen = 8.40 ± 1.53, left renal cortex = 9.62 ± 1.56, right renal cortex = 8.29 ± 1.63, and prostate = 8.20 ± 1.21), except for the renal medulla (left = 3.48 ± 0.68 and right = 2.95 ± 0.63) (P < 0.05). Our results indicated that strain elastography was feasible for estimating tissue stiffness in the canine liver, spleen, kidneys, and prostate. This study provides basic information for strain values and strain ratios for the liver, spleen, kidneys, and prostate in clinically normal dogs.     

INDIRECT AND DIRECT DETERMINATION OF THE PORTAL VEIN PRESSURE IN NORMAL AND ABNORMAL DOGS AND NORMAL CATS1

Portal hypertension resulting in ascites and portosystemic shunts leading to hepatoencephalopathy are major clinical manifestations of hepatic circulatory disease. Diffuse liver disease impairing sinusoidal blood flow can induce portal hypertension, portosystemic shunts, or both. The liver may also be involved secondarily in posthepatic hypertension and become the site of ascitic fluid formation. Portosystemic shunts may or may not be associated with portal hypertension. Selective catheterization of the hepatic and portal veins permits one to record pressures and to outline gross and subgross vascular anomalies by injecting contrast medium. Sequential pressure recordings in the caudal vena cava, in a free and wedged hepatic vein position, in the splenic pulp, and directly in the portal vein are the bases for the differentiation of prehepatic, liver-induced, and posthepatic portal hypertension. In addition to localizing the disease process along the postcaval-portal vein axis, pressure measurements are a reliable basis for the prognosis and selection of the most appropriate therapy. In dogs with portacaval shunts, wedge hepatic vein pressure recordings assist in the detection of hepatic sinusoidal anomalies that limit blood flow and preclude surgical ablation of the shunts. The various technics and their suitability for direct and indirect portal vein pressure recording are described and evaluated. Normal portal vein pressure values in 11 dogs and two cats, using different technics, are provided. The clinical usefulness of the various technics of pressure recording and angiography was illustrated in ten dogs with ascites, hepatoencephalopathy, or both.     

THE EFFECT OF A COMBINATION OF MEDETOMIDINE-BUTORPHANOL AND MEDETOMIDINE, BUTORPHANOL, ATROPINE ON GLOMERULAR FILTRATION RATE IN DOGS

The effects of intramuscularly administered medetomidine and butorphanol (MB), and medetomidine, butorphanol, atropine (MBA) on glomerular filtration rate (GFR) were determined in six dogs as measured by 99m-Tc-labeled diethylenetriaminepentaacetic acid (99mTc-DTPA) nuclear scintigraphy. Direct systolic, diastolic, and mean arterial blood pressures and heart rate were measured at regular time intervals before, during, and after GFR calculations. The mean GFR measurement following MB was significantly greater (4.44 ml/min/kg) than following MBA (3.82 ml/min/kg) or saline treatment (3.41 ml/min/kg). There was no significant difference between the mean GFR measurements following MBA injection and following saline injection. Diastolic and mean arterial pressures following MBA injection were significantly higher than the values recorded after either MB or saline alone. Heart rate following MB administration was significantly lower than that recorded for dogs receiving MBA or saline alone. The results of this study indicate that the administration of medetomidine in combination with butorphanol significantly increases total GFR in healthy dogs, while the administration of the combination of medetomidine, butorphanol, and atropine does not.     

ULTRASOUND-GUIDED TISSUE-CORE BIOPSY OF LIVER, SPLEEN AND KIDNEY IN NORMAL DOGS

Six normal dogs were subjected to ultrasound-guided biopsy of the liver, spleen and kidney to examine the accuracy of the technique (i.e. the presence of targeted tissue) and the histologic quality of the biopsies. Five consecutive tissue-core biopsies of each organ were taken on one or more occasions. The accuracy of the technique was 77% for hepatic, 90% for splenic, 53.5% for left kidney and 40% for right kidney biopsies. The histologic quality of the liver and kidney samples was sufficient, although for some samples the diagnostic value was limited by their size and in renal samples either cortical or medullary tissue was sometimes lacking. In contrast, the quality of the splenic sections was not good. The effect of reused and resterilized needles on the quality of the specimens was evaluated by histologic inspection of the samples and by the amount of biopsies lacking tissue. All tissue samples, including those taken with reused or resterilized needles had sharp-cut edges. Twenty-two of the total number of 120 biopsies (18%) contained no tissue. Absence of tissue in the samples was observed in biopsies taken with all needle types. The animals were observed for possible complications of the repeated needle biopsy. Apart from one case of hematuria, no complications were encountered.     

TECHNIQUE,DIFFICULTY, AND ACCURACY OF COMPUTED TOMOGRAPHY‐GUIDED TRANSLAMINAR AND TRANSFORAMINAL LUMBOSACRAL EPIDURAL AND INTRAARTICULAR LUMBAR FACET JOINT INJECTIONS IN DOGS

In human medicine, spinal pain and radiculopathy are commonly managed by computed tomography (CT)‐guided facet joint injections and by transforaminal or translaminar epidural injections. In dogs, CT‐guided lumbosacral epidural or lumbar facet joint injections have not been described. The aim of this experimental, ex vivo, feasibility study was to develop techniques and to assess their difficulty and accuracy. Two canine cadavers were used to establish the techniques and eight cadavers to assess difficulty and accuracy. Contrast medium was injected and a CT scan was performed after each injection. Accuracy was assessed according to epidural or joint space contrast opacification. Difficulty was classified as easy, moderately difficult, or difficult, based on the number of CT scans needed to guide insertion of the needle. A total of six translaminar and five transforaminal epidural and 53 joint injections were performed. Translaminar injections had a high success rate (100%), were highly accurate (75%), and easy to perform (100%). Transforaminal injections had an moderately high success rate (75%), were accurate (75%), and moderately difficult to perform (100%). Success rate of facet joint injections was 62% and was higher for larger facet joints, such as L7‐S1. Accuracy of facet joint injections ranged from accurate (37–62%) to highly accurate (25%) depending on the volume injected. In 77% of cases, injections were moderately difficult to perform. Possible complications of epidural and facet joint injections were subarachnoid and vertebral venous plexus puncture and periarticular spread, respectively. Further studies are suggested to evaluate in vivo feasibility and safety of these techniques.     

RADIOGRAPHIC, ULTRASONOGRAPHIC, AND COMPUTED TOMOGRAPHIC APPEARANCE OF ALVEOLAR ECHINOCOCCOSIS IN DOGS

Alveolar echinococcosis is a rare metacestodal infection of humans and domestic animals with Echinococcus multilocularis and predominantly affects the liver. In humans, diagnosis is based on serology, ultrasonography, computed tomography (CT), and magnetic resonance imaging (MRI), techniques that have not yet been validated for the diagnosis of alveolar echinococcosis in dogs. Therefore, the purpose of this retrospective study was to describe the radiographic, ultrasonographic, and CT appearance of canine alveolar echinococcosis. Eleven dogs with confirmed alveolar echinococcosis (PCR or histology from biopsy material of metacestode tissue) diagnosed between 1995 and 2003 were included in the study. The age of the dogs at initial presentation ranged from 7 months to 10.5 years. Abdominal radiographs were made in nine animals, abdominal ultrasonography was performed in 10 dogs, and two CT studies in one dog, respectively. The history, clinical presentation, and laboratory findings for the 11 dogs were unspecific, the most frequent clinical finding being nonpainful progressive abdominal distention. All radiographed dogs had large liver masses; they contained small mineralizations in five. The most frequent ultrasonographic finding was multiple large cavitary masses with or without wall mineralizations. Seven animals received surgical and subsequent medical therapy with albendazole (10mg/kg) and all went into clinical remission. This study reviewed for the first time imaging findings associated with alveolar echinococcosis. The disease has to be included in the list of differential diagnoses in dogs with large, cavitary liver masses, particularly when mineralization is noted.     

成鸡卵巢嗜酸性细胞、卵泡外腺细胞和卵泡膜腺细胞微细结构的研究

对成鸡卵巢的嗜酸性细胞、卵泡外腺细胞和卵泡膜腺细胞作H.E染色、油红—O染色和电子染色,然后进行光镜和电镜观察。结果:嗜酸性细胞单个分布在卵巢基质中,形态不一。胞核形态多样,异染色质数量中等,核仁位于核的偏中心部位。胞质中有许多电子密度较高的圆形嗜酸性颗粒,高尔基复合体发育良好,粗面内质网数量中等,有少量嵴少、基质电子密度低的线粒体,其它细胞器较少,油红—O染色阴性。卵泡外腺细胞分布在卵泡之间,由数个细胞结合成一细胞团。细胞形态多样。胞核圆形或卵圆形,一至数个核仁,异染色质少。胞质中充满大小不一的卵圆形脂滴,线粒体嵴多、基质电子密度较高,有管状嵴和板状嵴,还有较多囊泡状的滑面内质网,粗面内质网数量少,油红—O染色阳性反应。卵泡膜腺细胞也是数个细胞结合成一细胞团,分布在卵泡膜内层,结构与卵泡外腺细胞极为相似,油红—O染色阳性。卵泡外腺细胞和卵泡膜腺细胞都具有分泌类固醇激素细胞的结构特征。