DOUBLE CONTRAST GASTROGRAPHY IN THE CAT

Radiographic diagnosis of gastric mucosal disease has not been reported in the cat. This may be due to the difficulty in making these diagnoses with survey or single contrast radiography. Double contrast gastrography (DCG) allows direct visualization of gastric mucosal surfaces. The DCG technique in the cat is described, and the normal radiographic appearance is illustrated.     

DOUBLE CONTRAST GASTROGRAPHY IN THE NORMAL DOG

Double contrast gastrography affords more accurate detection of gastric lesions because it allows direct evaluation of mucosal pattern contours. The technic involves the induction of gastric hypomotility with intravenous glucagon, gastric intubation for the introduction of air and high-density barium directly into the stomach, and positional manipulation for maximal air-barium interface demonstration. Some dogs require sedation. Although fluoroscopic observation is an asset in isolating gastric anatomic abnormalities, this study may be performed using conventional radiographic equipment without fluoroscopic guidance. Double contrast gastrography is used to demonstrate the stomach mucosal surface by coating it with high-density barium and having the mucosa contrast with the air-filled gastric lumen. There are three elements to each double contrast image: the dependent surface, the nondependent surface, and the barium pool. The barium pool is manipulated to coat the mucosal surface and fill depressions of the dependent surface. Protrusions of the dependent surface appear as radiolucencies in the barium pool. Depressions and protrusions of the nondependent surface are outlined by barium. Double contrast gastrography is indicated in dogs where clinical signs suggest anatomic changes in the gastric mucosal surface, e.g., neoplasms, ulcers, or polyps. Concurrent gastrointestinal motility evaluation is precluded by sedation and the glucagon-induced gastric hypomotility.     

ULTRASONOGRAPHIC EXAMINATION OF CERVICAL MASSES IN THE DOG AND CAT

The ultrasonographic appearance of clinically undifferentiated neck masses for which a definitive diagnosis was eventually obtained in nineteen dogs and one cat is presented in this report. Multiple lesions were seen ultrasonographically in 4 dogs and no cervical abnormalities were seen in 2 dogs resulting in 22 lesions in 20 annuals. Of 7 benign lesions, there were 2 patients with reactive lymph nodes from a regional inflammatory process, and 1 patient each with primary pyogranulomatous lymphadenitis, arteriovenous malformation, foreign body granuloma, cellulitis, and hematoma. Of 15 malignant lesions, 7 were thyroid carcinomas, 3 were lymphomas with submandibular and cervical lymph node enlargement, 3 were lymph node enlargements associated with regional metastasis of malignant tumors, one was a leiomyosarcoma and one was a carotid body tumor. One dog with a diffuse soft tissue swelling of the ventral cervical region had only slight asymmetry of the thyroid lobes on ultrasound examination and no abnormalities of the neck at post mortem. A second dog examined with ultrasound 4 months after surgical removal of a carotid body tumor had no evidence of tumor recurrence. Ultrasonographic examination provided information regarding the character of the lesions, the tissue or organ of origin, and invasion into other anatomic structures. Ultrasound examination in conjunction with fine needle or tissue biopsy provided a definitive diagnosis in those animals in which biopsies were performed.     

ACQUIRED PORTAL COLLATERAL CIRCULATION IN THE DOG AND CAT

We describe patterns of acquired portal collateral circulation in dogs and in a cat using multidetector row computed tomography angiography. Large portosystemic shunts included left splenogonadal shunts in patients with portal hypertension. Small portal collaterals were termed varices; these collaterals had several patterns and were related either to portal vein or cranial vena cava obstruction. Varices were systematized on the basis of the venous drainage pathways and their anatomic location, namely left gastric vein varix, esophageal and paraesophageal varices, gastroesophageal and gastrophrenic varices, gallbladder and choledocal varices, omental varices, duodenal varices, colic varices, and abdominal wall varices. As reported in humans and in experimental dog models, esophageal and paraesophageal varices may result from portal hypertension that generates reversal of flow, which diverts venous blood in a cranial direction through the left gastric vein to the venous plexus of the esophagus. Blood enters the central venous system through the cranial vena cava. Obstructions of the cranial vena cava can lead to esophageal and paraesophageal varices formation as well. In this instance, they drain into the azygos vein, the caudal vena cava, or into the portal system, depending on the site of the obstruction. Gallbladder and choledocal varices, omental varices, duodenal varices, phrenico-abdominal varices, colic varices, abdominal wall varices drain into the caudal vena cava and result from portal hypertension. Imaging plays a pivotal role in determining the origin, course, and termination of these vessels, and the underlying causes of these collaterals as well. Knowledge about these collateral vessels is important before interventional procedures, endosurgery or conventional surgery are performed, so as to avoid uncontrollable bleeding if they are inadvertently disrupted.     

MAGNETIC RESONANCE IMAGING FEATURES OF PARASPINAL INFECTION IN THE DOG AND CAT

The magnetic resonance (MR) imaging findings in 22 dogs and two cats with confirmed paraspinal infection of the thoracolumbar spine were characterized. These findings included extensive T2-hyperintense areas (24/24), abscessation (20/24), mild inherent T1-hyperintensity of muscle and abscesses (18/24), and postcontrast enhancement (24/24). Changes involved the vertebral canal in four patients. The longus coli muscles were affected in one cat. Thoracolumbar changes in the remaining 23 patients involved the iliopsoas and epaxial muscles in 23/23 and 19/23 patients, respectively. Iliopsoas muscle abscessation was unilateral in 12/23, and bilateral in 6/24 patients. Abscessation involved both epaxial and iliopsoas muscles in 2/23 patients and the epaxial muscles alone in one patient. A contrast-enhancing sinus tract within the deep thoracolumbar fascia was present in 10/23 patients. Lumbar vertebrae periosteal reactions were identified in 19/23 patients on MR images compared with 15/17 patients with radiography. A focal area of signal void suspected to represent foreign material was seen in 5/23 patients but foreign material was actually found in only two of these five. There was no recurrence of clinical signs following MR imaging and revision surgery. MR imaging permits the severity and extent of changes associated with paraspinal infection to be characterized and allows the location, number and any communication of sinus tracts to be documented.     

IOHEXOL AS A GASTROINTESTINAL CONTRAST MEDIUM IN THE CAT

Iohexol was evaluated as a radiologic contrast medium in the gastrointestinal (GI) tract in cats. Three different doses (525, 700, 875 mg iodine/kg with an iodine concentration of 300 mg iodine/mL) diluted with tap water until a total volume of 10 ml/kg, were administered via an orogastric tube, to 5 cats at weekly intervals. The GI transit time was rapid and variable. Gastric emptying commenced immediately after administration of the contrast medium and was complete within 10–30 min. In each dose, iohexol reached the large intestine within 10–20 min. In 73% (11/15) of studies, the mucosal border appeared as a thin homogeneous "halo" of lucency surrounding the more opaque contents of the small intestine. Radiographic image quality of the GI tract was inadequate with the lowest dose (525 mg iodine/kg). Image quality did not deteriorate along the GI tract. Absorption of iohexol from the GI tract was observed in 40% (6/15) of examinations, where opacification of the urinary bladder was seen. No side effects were observed. lohexol should be considered as an alternative GI contrast medium in the cat when the use of other radiologic contrast media is contraindicated.     

REVIEW OF DIAGNOSTIC IMAGING OF EAR DISEASES IN THE DOG AND CAT

Diagnostic imaging techniques (conventional radiography, computed tomography and magnetic resonance imaging) are an essential tool in the diagnostic work-up of ear diseases. Conventional radiography is commonly used, but often lacks sensitivity. Computed tomography (CT) and magnetic resonance (MR) are complementary imaging studies of the middle ear, labyrinth, internal auditory canal and their contents. CT provides excellent images of bony structures and is indicated where osseous changes are of greatest diagnostic importance. MR is superior in imaging soft tissue components including intralabyrinthine fluid. Therefore, more than one of these imaging techniques may be required in order to make a diagnosis.     

USE OF IOHEXOL AS A GASTROINTESTINAL CONTRAST MEDIUM IN THE DOG

Iohexol was administered orally in five dogs. The dose, gastrointestinal (GI) transit time, appearance of mucosal patterns and side effects were studied. Three different doses (525, 700, 875 mgI/kg) were used in each dog at 1-week intervals. GI transit time was rapid. In each dose, gastric emptying commenced immediately after administration of the contrast medium, and was completed within 30–60 min with doses of 525–700 mgI/kg and 90–120 min with 875 mgI/kg. Large intestinal filling was observed within 60-90 min. In the majority of studies, the mucosal border appeared as a thin homogeneous halo of lucency surrounding the more opaque bowel lumen contents. The contrast intensity was not adequate with the lowest dose. The image quality did not deteriorate along the GI tract. No adverse reactions were found. Iohexol is an alternative GI contrast medium in the dog when contrast media are contraindicated.     

NON-SELECTIVE ANGIOCARDIOGRAPHY IN THE NORMAL DOG AND CAT

Non-selective angiocardiograms were performed on clinically normal mature dogs and cats to determine the optimal contrast medium dose. A dose of 200 mg of iodine per 0.45 kg of body weight was found to give the most consistent results. A 105 mm spot film camera was used at a speed of 2 frames per second. No study took longer than 11 seconds to complete. The technique provided good visualization of the cranial vena cava, pulmonary outflow tract, the pulmonary arteries, left atrium, left ventricle and aorta. The technique provided fair visualization of the right atrium, right ventricle, valves and papillary muscles     

INPACTION OF THE PHARYNX, LARYNX, AND ESOPHAGUS BY AVIAN BONES IN THE DOG AND CAT

Avian osseous (mandible, thoracic and caudolateral processes and furculum) foreign body impaction in the larynx, pharynx, and esophagus is described in three cats and one dog. All animals were presented because of gagging. Radiographic assessment revealed the foreign body in each animal. Each foreign body was successfully removed. Three of the animals recovered uneventfully, and one had a persistent change of voice.     

COMPUTED TOMOGRAPHY-GUIDED PERCUTANEOUS BIOPSY IN THE DOG AND CAT: DESCRIPTION OF TECHNIQUE AND PRELIMINARY EVALUATION IN 14 PATIENTS

A technique for computed tomography (CT)-guided percutaneous biopsy described for use in humans was adapted to the dog and cat and is evaluated in 14 patients. Nine retrobulbar, 1 cranial mediastinal and 4 pulmonary masses and 1 hilar lymph node were biopsied in 13 dogs and 1 cat. Tissue samples sufficient for diagnosis were obtained in 12 of the 15 lesions. Diagnoses were made following cytologic (3/12) or histopathologic (3/12) evaluation or both (6/12) and included retrobulbar lymphoma, carcinoma, spindle cell sarcoma and suppurative inflammation; pulmonary carcinoma, granuloma and eosinophilic/histiocytic inflammation; nasal carcinoma, thymoma and metastatic carcinoma of a hilar lymph node. In each patient, the needle tip was identified within the lesion on the CT image. The primary limitation was non-diagnostic samples in 3 of 15 lesions due to necrosis or insufficient tissue. Complications were minor. In addition to biopsy guidance, CT imaging provided information not obtainable with fluoroscopy or ultrasonography which assisted in tumor staging and therapy planning. Although a larger number of patients and biopsy locations would be required for a thorough assessment, the free-hand technique described in this preliminary report appeared to be a safe and useful option of biopsy guidance in the dog and cat.     

MAGNETIC RESONANCE IMAGING OF THE NORMAL EYE AND ORBIT OF THE DOG AND CAT

Magnetic resonance (MR) images of the normal eye and orbit of the dog and cat were acquired. T1-weighted, proton-density, and T2-weighed images were obtained in the oblique dorsal, straight sagittal, and oblique sagittal planes. Signal intensity for the various orbital structures differed among the three resonance techniques. T1-weighted images provided the greatest contrast of the retrobulbar structures. T-1 weighted images also had the highest signal to noise ratio, thereby providing the best anatomic detail. Anatomic components of the globe, retrobulbar structures and ocular adnexa were easily seen in all MR sections. The oblique dorsal and oblique sagittal planes were superior for evaluating the optic nerve in its entirety.     

ANGIOGRAPHY OF THE HEPATIC AND PORTAL VENOUS SYSTEM IN THE DOG AND CAT: AN INVESTIGATIVE METHOD*

The investigators studied the hepatic angiographic technics used in human medicine with respect to their applicability for the investigation of circulatory liver diseases in the dog and cat. The technics were performed in 11 normal dogs and 2 normal cats, and the normal radiographic anatomy of the hepatic portal system and its tributaries was described. The potential indications for the angiographic technics were defined and their respective advantages and disadvantages discussed. Splenoportography was a valuable method for outlining the intrahepatic portal vein branches and for percutaneous prehepatic portal vein pressure determination. Percutaneous transhepatic portography was more difficult to perform, but it provided better detail of the intrahepatic portal veins than splenoportography. Transjugular transhepatic portography was the most versatile but also the most cumbersome of all technics tested. Percutaneous kinetic hepatography proved impractical in dogs and cats. The mesenteric tributaries to the hepatic portal system were best outlined by cranial mesenteric arterial portography or by operative mesenteric venous portography. Operative mesenteric venous portography, in contrast to cranial mesenteric arterial portography, was also useful for prehe-patic portal vein pressure determination. Free and wedged hepatic venography provided an opportunity for the functional and morphologic investigation of the hepatic sinusoid circula-tion.     

MR EVALUATION OF INTRA AND EXTRACRANIAL EXTENSION OF NASAL ADENOCARCINOMA IN A DOG AND CAT

Nasal adenocarcinomas have been reported to extend into the cranial vault and cause neurologic disease. This report discusses a dog and cat with nasal adenocarcinoma which extended into the retrobulbar space, base of the cranial vault and adjacent soft tissues. The invasive characteristics of the neoplasms were documented by magnetic resonance imaging (MRI). Documentation of the extent of tumor is important if radiation therapy or surgery is planned. MRI was valuable in identifying extracranial and intracranial tumor invasion in these patients.     

ULTRASONOGRAPHIC FEATURES OF PERITONEAL CESTODIASIS CAUSED BY MESOCESTOIDES SP. IN A DOG AND IN A CAT

Peritoneal infections caused by Mesocestoides spp. are rare in dogs and cats. Little data exist on the role of abdominal ultrasonography for diagnosis and therapy management of the disease. We describe the ultrasonographic features of peritoneal cestodiasis in a dog and in a cat. In the dog, abdominal ultrasound allowed both a presumptive diagnosis and the collection of tissue samples to confirm peritoneal larval infection. Ultrasound was also very useful for therapy management. In the second patient the ultrasonographic features of tetrathyridial infection in a cat in which the parasite was observed as an incidental finding during ovariohysterectomy are described.     

IMAGING ASSESSMENT OF THE MODIFIED DOUBLE CONTRAST BARIUM ENEMA USING CARBOXYMETHYLCELLULOSE ON RADIOGRAPHY AND ULTRASONOGRAPHY IN DOGS

A modified double contrast barium enema using carboxymethylcellulose was evaluated in beagle dogs and compared with dogs receiving a conventional barium enema. The experimental group was divided into three groups (1, 2, and 3) and given 30 ml/kg of different volume ratios of a barium vs. carboxymethylcellulose mixture. Each group underwent sonography following radiography. The volume ratio of one part barium to three parts carboxymethylcellulose was judged to be the optimal mixture, resulting in a general distribution of contrast and bowel radiolucency on radiographs and adequate postradiography sonography. The modified barium enema using carboxymethylcellulose is useful for assessing the general morphology and mucosal layers of the colon simultaneously on radiographs and ultrasonographs.     

PROSTATIC REFLUX DURING POSITIVE CONTRAST RETROGRADE URETHROGRAPHY IN THE DOG

Forty-five positive contrast retrograde urethrograms in which contrast medium reflux into the prostate was identified were evaluated to determine whether a correlation existed between the time and pattern of reflux and the nature of the prostatic disease. Prostatic diseases identified included prostatitis (25 dogs), prostatic tumor (13 dogs), and prostatic hyperplasia (1 dog). Six dogs with contrast medium reflux had no evidence of prostatic disease. No correlation was found between presence of prostatic reflux and specific prostatic diseases; however, prostatic tumor or infection was observed more frequently than hyperplasia, metaplasia, or cyst in the dogs with contrast medium reflux. A linear pattern and irregular, indistinct margination of the contrast medium reflux were associated with prostatitis; however, these patterns were also observed in dogs without prostatic disease     

LYMPHOMA AFFECTING THE URINARY BLADDER IN THREE DOGS AND A CAT

Three dogs and one cat with lymphoma affecting the urinary bladder are reported and the findings on abdominal radiographs and ultrasound are described. Mural lesions representing lymphoma affecting the urinary bladder were identified ultrasonographically in all animals. The most common complications associated with urinary bladder lymphoma were hydronephrosis and hydroureter. In two patients contrast radiography was necessary to detect leakage of urine in the peritoneal and retroperitoneal space. The radiographic and ultrasonographic signs were similar to those reported with other urinary bladder neoplasms; hence urinary bladder lymphoma could not be distinguished from the more common urinary bladder neoplasms, such as transitional cell carcinoma. It is important to include lymphoma in the differential diagnosis of urinary bladder wall thickening and mural mass in dogs and cats.