PLEURAL FLUID MOVEMENT

The present study was an attempt to illustrate the differences between ventrodorsal (VD) and dorsoventral (DV) radiographs that result from the movement of free pleural fluid. A volume of 25 ml/kg of normal saline was introduced into the pleural space of a normal dog, and radiographs of the thorax were produced in ventral and dorsal recumbency using a vertical (overhead) x-ray beam and a laterally directed horizontal x-ray beam. On the DV projection (ventral recumbency) the heart, cranial mediastinum, cranial lung lobes, and the ventral aspect of the diaphragm were submersed in fluid, which resulted in the loss of radiographically detectable borders. On the VD projection (dorsal recumbency) radiographic visualization of these structures was improved due to movement of the free pleural fluid away from them, toward the dependent caudodorsal aspect of the thorax. Radiographs of three dogs with spontaneous pleural effusion are presented to illustrate the differences in radiographic appearance of the thorax with pleural effusion when radiographed in DV and VD projections. The movement of fluid to the dorsocaudal thoracic cavity in dorsal recumbency caused lesions that were obscured on the DV projection to be revealed on the VD projection. the authors therefore recommend the use of the VD projection of the thorax in patients with pleural fluid when clinical status permits.     

COMPARISON BETWEEN MAGNETIC RESONANCE IMAGING ESTIMATES OF EXTRACRANIAL CEREBROSPINAL FLUID VOLUME AND PHYSICAL MEASUREMENTS IN HEALTHY DOGS

Dosages for myelography procedures in dogs are based on a hypothetical proportional relationship between bodyweight and cerebrospinal fluid (CSF) volume. Anecdotal radiographic evidence and recent studies have challenged the existence of such a defined relationship in dogs. The objectives of this prospective cross‐sectional study were to describe CSF volumes using magnetic resonance imaging (MRI) in a group of clinically healthy dogs, measure the accuracy of MRI CSF volumes, and compare MRI CSF volumes with dog physical measurements. A sampling perfection with application optimized contrast using different flip‐angle evolution MRI examination of the central nervous system was carried out on 12 healthy, male mongrel dogs, aged between 3 and 5 years with a bodyweight range of 7.5–35.0 kg. The images were processed with image analysis freeware (3D Slicer) in order to calculate the volume of extracranial CSF. Cylindrical phantoms of known volume were included in scans and used to calculate accuracy of MRI volume estimates. The accuracy of MRI volume estimates was 99.8%. Extracranial compartment CSF volumes ranged from 20.21 to 44.06 ml. Overall volume of the extracranial CSF increased linearly with bodyweight, but the proportional volume (ml/bodyweight kilograms) of the extracranial CSF was inversely proportional to bodyweight. Relative ratios of volumes in the cervical, thoracic, and lumbosacral regions were constant. Findings indicated that the current standard method of using body weight to calculate dosages of myelographic contrast agents in dogs may need to be revised.     

SONOGRAPHIC ASSESSMENT OF GALLBLADDER VOLUME IN NORMAL CATS

We quantified gallbladder volume in 30 clinically healthy, fasted, cats, using an ellipsoid formula. All cats had a complete blood count and serum chemistry profile performed. Fasting times before sonography ranged from 12 to 16 h. The median gallbladder volume was 2.42 ml, with a range of 0.84–4.50 ml. The mean gallbladder volume was 2.41 ml. This reference range will assist clinicians when evaluating cats with hepatobiliary disease or suspected extrahepatic biliary obstruction.     

SONOGRAPHIC SIGNS OF GASTRODUODENAL LINEAR FOREIGN BODY IN 3 DOGS

This article describes the sonographic signs identified in three dogs with confirmed gastroduodenal linear foreign bodies. The sonographic signs included the following; an abnormal tortuous path of the descending duodenum, the presence of a hyperechoic linear structure within the duodenal lumen which was carefully followed orally to the pylorus. The presence of a mass with strong acoustic shadow within the pylorus may also be imaged. The normal intestinal layers were present in the duodenal wall. In real time, the intestinal path was followed through many "hairpin" turns, and during this process the lumen was observed for identification of a linear structure. Secondary sequelae of gastrointestinal perforation were more difficult to identify with confidence in the cases presented.     

HEPATIC VOLUME ESTIMATION USING QUANTITATIVE COMPUTED TOMOGRAPHY IN DOGS WITH PORTOSYSTEMIC SHUNTS

The purpose of this study was to use quantitative computed tomography (CT) to estimate liver volume in dogs with a portosystemic shunt and to compare the liver volume in normal dogs to dogs with a shunt. Twenty-one dogs with a portosystemic shunt underwent contrast-enhanced abdominal CT for shunt characterization and preoperative planning. Six dogs without clinical signs relating to liver disease were used as a control group. In addition, liver volume was compared before and 2-4 months after surgical shunt attenuation in three dogs. All studies followed established clinical imaging protocols. Liver margins were defined on each image using an operator-defined region of interest and hepatic volume renderings were produced from which the liver volume was quantitatively estimated. There was a statistically significant association between liver volume and body weight in control and shunt dogs (r = 0.909 and 0.899, respectively, P < 0.01). Liver volume normalized to body weight was 15.5 +/- 5.2 cm3/kg in affected dogs and 24.5 +/- 5.6 cm3/kg in control dogs. Based on postligation CT studies in three affected dogs, liver volume increased by 43%, 51%, and 62%. Hepatic volume estimation may be a clinically useful parameter in the initial and postsurgical evaluation of dogs with portosystemic shunts.     

ULTRASONOGRAPHIC DETERMINATION OF RENAL VOLUME IN THE DOG

Ultrasonographic linear and area measurements were performed on both kidneys of 15 clinically healthy dogs. Renal volumes were calculated from linear and area data applying three prolate ellipsoid models. Ultrasonographic volumes were then compared using linear regression analysis with kidney volumes measured in vitro by water displacement. In vivo ultrasonographic volumes had a statistically significant relationship with the in vitro volume. The highest correlation was provided by the single plane area method. There was also a correlation between body weight and ultrasonographically detected renal volume, suggesting that ultrasound imaging may be a useful method for assessment of renal volume changes in dogs with renal disease.     

SONOGRAPHIC APPEARANCE OF UREMIC GASTROPATHY IN FOUR DOGS

Gastrointestinal signs are common in dogs with uremia. Structural changes in the stomach associated with uremia in dogs include ulceration, edema, necrosis, gastric wall thickening, submucosal arteriopathy, and mineralization of the gastric mucosa and submucosa. Upon ultrasonographic evaluation of the abdomen in four dogs with severe uremia due to chronic renal disease, a thickened gastric wall, thickened rugal folds, and a hyperechoic line at the mucosal-luminal interface due to mineralization of the gastric mucosa were found. Ultrasonography was more sensitive than survey radiography for the identification of gastric lesions associated with uremia in these dogs.     

CEREBROSPINAL FLUID SIGNAL-VOID SIGN IN DOGS

The cerebrospinal fluid signal-void sign is an observable signal loss from cerebrospinal fluid (CSF), especially on T2-weighted magnetic resonance (MR) images. In people, this sign is attributed to rapid CSF flow or turbulence from arterial pulsations and occurs more frequently with reduced intracranial compliance. The purposes of this study were to describe the CSF signal-void sign, document whether a similar sign occurs in dogs and investigate associations between it and other conditions. The sample population consisted of 327 dogs admitted for neurocranium evaluation using a 0.2 T system. Review of the medical records and MR images was performed to characterize the presence and location of a CSF signal-void sign, ventricular size, syringomyelia, and other lesions. A CSF signal-void sign was detected in at least the mesencephalic aqueduct in 59/327 (18.0%) dogs, including some with no morphologic brain abnormality. The majority of these dogs (45/59% or 76%) weighed <15 kg. In two other dogs, a CSF signal-void sign was detected only in a cervical syrinx. In dogs weighing >15 kg, a CSF signal-void sign was seen with various conditions. In 137/327 (41.9%) dogs weighing <15 kg, the presence of a CSF signal-void sign in the aqueduct (45 dogs) was associated with syringomyelia ( P =0.0468) and increased ventricular size ( P =0.0054): syringomyelia also was associated with increased ventricular size ( P =0.0009). In conclusion, a CSF signal-void sign was seen in dogs with various conditions. In small-breed dogs, a CSF signal-void sign in the aqueduct was associated with ventricular enlargement and syringomyelia.     

SONOGRAPHIC APPLICATION IN THE DIAGNOSIS OF INTRAABDOMINAL ABSCESS IN THE DOG

The sonographic appearance of intraabdominal abscess, excluding prostatic abscess, is presented. The most common sonographic pattern identified for intraabdominal abscess is an irregularly defined, hypoechoic mass with minimal to no through transmission. Definitive diagnosis of intraabdominal abscess using only sonography is not possible, as variations of this common sonographic pattern are imaged. Sonography is best utilized to scan an animal when there is a high suspicion of intraabdominal abscess with no overt physical or radiographic evidence, and to better characterize intraabdominal masses. Sonography can be used to assist in percutaneous aspiration, catheterization, and intraoperative localization of abscessation.     

COMPARISON OF SONOGRAPHIC FEATURES OF BENIGN AND NEOPLASTIC DEEP LYMPH NODES IN DOGS

The differentiation of benign vs. neoplastic lymph nodes impacts patient management. Specific sonographic features are typically considered when assessing lymph nodes in dogs. However, the usefulness of these criteria in distinguishing benign vs. malignant lymph nodes remains largely unknown, especially for deep lymph nodes. Our aim was to compare sonographic features in benign and neoplastic deep lymph nodes with the hope of identifying predictive criteria. Thirty‐one deep lymph nodes (16 mesenteric, 10 medial iliac, three hepatic, one sternal, and one cranial mediastinal) in 31 dogs were examined prospectively with B‐mode and Color flow Doppler. Lymph nodes were aspirated using ultrasound‐guidance and final diagnosis were established based on cytologic and/or histopathologic interpretation. Prevalence of each sonographic feature and combinations of two features was calculated for each group and compared using a χ²‐test or Student's t‐test for unequal variances. Ten lymph nodes were benign (hyperplastic and/or inflammatory) and 21 were neoplastic. All were hypoechoic, except for one neoplastic lymph node. Maximal short‐axis diameter (P=0.0006) and long‐axis diameter (P=0.01), and SA/LA ratio (P=0.008) were increased significantly for neoplastic (2.8, 5.5 cm, and 0.50, respectively) vs. benign (1.2, 3.8 cm, and 0.34, respectively) lymph nodes. The prevalence of other features was similar between groups. Doppler evaluation was possible in 77% of lymph nodes, but there was no significant difference between groups. When any two ultrasound features were combined, the only difference between benign and neoplastic lymph nodes was for the combination of contour regularity and appearance of the perinodal fat (P=0.03).     

SONOGRAPHIC APPEARANCE OF RENAL NEOPLASIA IN THE DOG

Eight dogs with renal neoplasia were radiographically and sonographically examined. An enlarged, nonopacified kidney was seen on the excretory urogram in four dogs, but differentiation between a solid mass or severe hydronephrosis was not possible. The excretory urogram suggested an avascular lesion in one kidney, but differentiation between solid or cystic disease was not possible. Renal neoplasia was diagnosed in two dogs by excretory urography. Radiographic examination suggested splenic neoplasia in one dog. Solid masses were sonographically diagnosed in all dogs. A metastatic lesion was sonographically diagnosed in the opposite kidney of one dog that was missed on the radiographic examination. Ultrasonography com-plemented radiography as a diagnostic modality in eliciting additional information on renal disease. Sonograms did not allow determination of tumor cell type or whether the tumor was benign or malignant.     

DOPPLER ULTRASOUND OF THE PROSTATE IN NORMAL DOGS AND IN DOGS WITH CHRONIC LYMPHOCYTIC-LYMPHOPLASMOCYTIC PROSTATITIS

The prostate gland of 11 normal dogs and five dogs with histological confirmed chronic lymphocytic or lymphoplasmocytic prostatitis were imaged with grey-scale and Doppler ultrasound. Three vessel types (prostatic artery, capsular artery and parenchymal artery) were identified with color Doppler and the resistive index and maximum and minimum velocities were measured with pulsed wave Doppler. No differences between normal dogs and dogs with prostatitis was identified in either grey-scale ultrasound or in any Doppler parameters measured. Regardless of histologic diagnosis, acepromazine (0.05 mg/kg IV) caused a significant decrease in capsular artery maximum and minimum velocities and prostatic artery resistive index. This study establishes normal Doppler ultrasound parameters for the intact male canine prostate gland. Additional studies are necessary to further evaluate the clinical utility of Doppler ultrasound in canine prostatic diseases.     

THE USE OF INTRAPERITONEAL FLUID AS A SIMPLE TECHNIQUE FOR ENHANCING SONOGRAPHIC VISUALIZATION OF THE CANINE PANCREAS

Sonographic evaluation of the pancreas was performed in ten healthy research dogs following intraperitoneal fluid administration. Physiological saline solution was aseptically introduced into the peritoneal cavity of each dog to create an acoustic window that would facilitate sonographic delineation of normal pancreatic tissues. Abdominal ultrasound examinations were performed in all dogs before and after the production of the diagnostic hydroperitoneum. Sonograms of the pancreas and other abdominal organs were scored on the basis of image clarity by experienced and novice ultrasonographers. Statistical analysis was then used to compare the effectiveness of each preparation method. A significant difference (P < 0.05) was established between the scores from the diagnostic hydroperitoneum sonograms and the baseline scans performed without intraperitoneal fluid placement. Sonographic visualization scores for the pancreas and other abdominal organs were increased following production of the diagnostic hydroperitoneum. These results indicate that the technique of diagnostic hydroperitoneum will significantly improve ultrasonographic visualization of the pancreas, and may prove useful in the diagnosis of canine pancreatic disease.     

HYPERCALCEMIC NEPHROPATHY IN THREE DOGS: SONOGRAPHIC APPEARANCE

Persistent hypercalcemia in the dog is most commonly seen as a paraneoplastic syndrome or in association with widespread osteolytic lesions. In high concentrations calcium is a potent nephrotoxin and may cause severe and irreversible renal damage. The ultrasonographic changes in the kidneys of three dogs with hypercalcernic nephropathy are described'and compared with the changes described in the same human condition. It is suggested that ultrasound could be a useful technique for evaluation of the severity of renal damage and the potential return of renal function in such instances.     

ESTIMATION OF BLADDER VOLUME USING ULTRASONOGRAPHIC DETERMINATION OF CROSS-SECTIONAL AREAS AND LINEAR MEASUREMENTS

The purpose of this study was to determine if ultrasonographic measurement of multiple cross-sectional areas combined with linear dimensions of the bladder could be used as a method of estimating bladder volume in the dog, and, if so, to compare the accuracy of this estimation with that described previously using linear measurements alone. Fifty-two live dogs undergoing investigation for urological disease and 37 fresh canine cadavers were used for bladder volume determination. Maximal length, depth, width, and area were measured from the maximal longitudinal and transverse sonograms in each living animal. In cadavers, the cross-sectional area of the longitudinal section of the bladder was measured at one centimeter intervals, and the measurements were summed. Based on sequential partial regression analysis, the cross-sectional area of the longitudinal section of the bladder and length were the best predictors of actual bladder volume in living animals. However, based on the cadaver experiment, the best predictor of actual bladder volume was summed parasagittal area alone, and, in cadavers, this was a much better predictor of actual bladder volume than the combination of the cross-sectional area of the longitudinal section of the bladder and length. The formula derived in living dogs using the corss-sectional area of the longitudinal section of the bladder and length gave a less accurate estimation of bladder volume than a previously published formula where only linear measurements were used.     

SONOGRAPHIC RENAL FINDINGS IN 20 DOGS WITH LEPTOSPIROSIS

Abdominal ultrasound examinations of 20 dogs with confirmed leptospirosis were reviewed retrospectively for renal abnormalities. Three dogs had a normal ultrasound examination. The remaining 17 dogs had sonographic abnormalities of the kidneys. These abnormalities, seen either alone or in combination, included renalmegaly (n=10), pyelectasia (n=9), increased cortical echogenicity (n=15), perinephric effusion (n=5), and a medullary band of increased echogenicity (n=6). At our institution, the medullary band of increased echogencity has only been seen in dogs with leptospirosis and may therefore be a specific sonographic sign for this disease.     

ULTRASONOGRAPHIC FEATURES OF UTERUS MASCULINUS IN SIX DOGS

Uterus masculinus (persistent Mullerian duct) is a vestigial embryological remnant of the paramesonephric duct system in males and has been associated with clinical signs such as dysuria, incontinence, tenesmus and urethral obstruction in dogs. The radiological appearance of cystic uterus masculinus in dogs has been described previously with the aid of retrograde positive or negative contrast cystography. The purpose of this retrospective study was to describe ultrasonographic features of confirmed or presumed uterus masculinus in a group of dogs with confirmed or presumed disease. Ultrasonographic findings were recorded based on a consensus opinion of two readers. A uterus masculinus was defined as cylindrical when no lumen was observed and tubular when it had lumen that was filled with anechoic fluid. Six dogs met the inclusion criterion with a mean age of 8 years and 9 months. Uterus masculinus appeared as single (four dogs) or two (two dogs) horn‐like, tubular (four dogs) or cylindrical (two dogs) structures, originating from the craniodorsal aspect of the prostate gland and extending cranially. The walls of the uterus masculinus were isoechoic to the urinary bladder wall. The diameter of the observed uterus masculinus varied from 0.3 cm to 1 cm. The length of the uterus masculinus varied from 2 cm to 6.5 cm but the cranial terminal end was not identified in two dogs. Concomitant prostatomegaly was seen in five dogs (83.3%) and urinary tract infection was noted in three dogs (50%). Findings indicated that uterus masculinus should be included as a differential diagnosis for male dogs with these ultrasonographic characteristics.     

A COMPARISON OF TWO-DIMENSIONAL ULTRASONOGRAPHY AND RADIOGRAPHY FOR THE DETECTION OF SMALL AMOUNTS OF FREE PERITONEAL FLUID IN THE DOG

The detection of small amounts of free peritoneal fluid in the canine patient can be a diagnostic dilemma. Ultrasonography and radiography have been advocated to detect intraabdominal fluid not detectable by physical exam. The purpose of this study was to determine the more sensitive method for detecting small amounts of free peritoneal fluid. Ultrasound examinations and radiographs were performed after increments (1 ml/lb body weight) of fluid were injected intraperitoneally. Ultrasonography detected fluid in one animal at 2 ml/lb. AH other animals had fluid detected at 3 ml/lb. With radiographs fluid could be detected with a high degree of accuracy at 4 ml/lb. The lateral view was more accurate than the ventrodorsal view in detecting fluid. The authors concluded that Ultrasonography is more sensitive than radiography and is the method of choice to detect small amounts of free peritoneal fluid.     

SONOGRAPHIC EVALUATION OF EXPERIMENTAL BILE DUCT LIGATION IN THE DOG

The common bile duct was surgically ligated in five normal adult dogs. Ultrasonographic examinations of the gallbladder and biliary system were performed after duct ligation at intervals of 24 hours. The sequence of biliary system dilation was from the common duct to the peripheral intrahepatic ducts. Common duct enlargement was evident in 24–48 hours, while peripheral biliary duct dilation was recognized by five to seven days after obstruction. When compared with hepatic and portal veins, dilated biliary ducts were more tortuous and had irregular branching patterns. Gross pathologic changes were correlated with ultrasonographic findings at seven, 14, 15, 18 and 21 days after obstruction.     

MAGNETIC RESONANCE IMAGING FINDINGS IN 25 DOGS WITH INFLAMMATORY CEREBROSPINAL FLUID

To describe the signs that may be associated with intracranial inflammatory conditions, magnetic resonance (MR) images of 25 dogs that had inflammatory cerebrospinal fluid (CSF) were mixed with those of a control group of 40 dogs that had CSF negative for inflammatory disease and reviewed without knowledge of the clinical signs or diagnosis. CSF was considered inflammatory if the protein level was > 0.25 g/l and the white cell count was > 5 mm(-3). Abnormalities were found by MR imaging in 19 (76%) dogs with inflammatory CSF. Two dogs had focal lesions, 10 had multifocal lesions, and seven had diffuse lesions. Lesions affected all divisions of the brain. Mass effect was identified in seven (28%) dogs, including one that had a choroid plexus carcinoma. Lesions were hyperintense in T2-weighted images in 18 dogs and hypointense in T1-weighted images in six dogs. Multifocal or diffuse intraaxial lesions that were hyperintense in T2-weighted images were observed in 17 (68%) dogs with inflammatory CSF. Administration of gadolinium resulted in enhancement of intraaxial lesions in nine (36%) dogs and enhancement of meninges in seven (28%) dogs. Six (24%) dogs with inflammatory CSF had images interpreted as normal.