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.     

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.     

DOUBLE VERSUS SINGLE CONTRAST GASTROGRAPHY IN THE DOG AND CAT

It was hypothesized that double contrast gastrography (DCG) in the dog and cat would be more sensitive and specific than single contrast gastrography (SCG). In 13 dogs and three cats single and double contrast studies were performed and final diagnoses confirmed. DCG was found to be more sensitive and specific than SCG in detection of gastric disease. The loss of specificity of DCG was due entirely to technical difficulties that when recognized, were avoidable. The increased sensitivity of DCG included the ability to characterize the appearance as well as the location of the lesion. A discussion of the DCG appearance of some gastric lesions is included.     

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.     

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.     

A REVIEW OF PRIMARY LUNG TUMORS IN THE DOG AND CAT

Primary pulmonary carcinomas are being encountered with increasing frequency in older dogs and cats. The most common presenting complaint in the canine is a nonproductive cough of several weeks' duration, but many affected animals have no abnormal clinical signs in the early stages of the disease. A solitary mass that arises from a single focus in the peripheral pulmonary tissue is the most frequently observed radiographic sign of a primary lung tumor. Often a definitive diagnosis can be made only following thoracotomy with removal or biopsy study of the neoplastic tissue. A classification system based on the prevailing histologic pattern may then be used to categorize most primary lung neoplasms as adenocarcinomas, squamous cell carcinomas, anaplastic carcinomas, or bronchioloalveolar carcinomas. Adenocarcinomas are most common in the dog and cat. Only the neoplastic cell type and the presence or absence of metastatic disease have been found to be of value as prognostic indicators. Following wide surgical resection of the pulmonary mass, dogs with pulmonary adenocarcinomas are reported to have a longer mean survival time than animals with other types of primary lung carcinomas.     

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.     

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.     

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.     

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.     

ULTRASONOGRAPHY OF LARYNGEAL MASSES IN SIX CATS AND ONE DOG

Ultrasonography of laryngeal abnormalities in small animals allows the identification of laryngeal masses because of the resulting distortion of normal structural/anatomical relationships. It also allows fine-needle aspirates to be taken with minimal risk of causing hemorrhage or edema affecting the already narrowed laryngeal lumen. Findings in six cats and one dog with laryngeal abnormalities are described.     

THE ROLE OF ULTRASOUND IN THE ASSESSMENT OF LARYNGEAL PARALYSIS IN THE DOG

Forty dogs with clinical signs suggestive of upper respiratory tract disease underwent echolaryngography and laryngoscopy. Laryngoscopy was used as the definitive technique to diagnose laryngeal paralysis. The ultrasound investigation accurately indicated the presence of the paralysis and confirmed the uni- or bilateral nature of the disorder. Findings indicative of laryngeal paralysis included asymmetry or absence of motion of the cuneiform processes (30/30), abnormal arytenoid movement (16/30), paradoxical movement (9/30), caudal displacement of the larynx (2/30) and laryngeal collapse (1/30). Thirty dogs were found to be afflicted with laryngeal paralysis and ten had normal laryngeal motility.     

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.     

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.     

RADIOGRAPHIC CHANGES ASSOCIATED WITH DIGITAL, METACARPAL AND METATARSAL TUMORS, AND PODODERMATITIS IN THE DOG

Fifty-two of digital, metacarpal or metatarsal canine tumors and 48 pododermatitis lesions were reviewed retrospectively. The tumors were divided into 42 malignant neoplasms, 6 benign neoplasms and 4 non-neoplastic tumor-like growths. The distribution and radiographic changes of the lesions associated with the tumors and inflammation were compared. Pododermatitis and benign processes could not be radiographically differentiated from malignant neoplasms of the foot; however, lesions exhibiting osteolysis were more likely (p < 0.05) to be associated with malignant neoplasms.     

CELLULAR FEATURES OF SONOGRAPHIC TARGET LESIONS OF THE LIVER AND SPLEEN IN 21 DOGS AND A CAT

Target lesions are seen in ultrasound images of the liver or spleen as nodules or masses with a hypoechoic rim and a hyperechoic or isoechoic center. To assess the diagnostic significance of finding a target lesion, the cytologic and/or histopathologic findings were reviewed in a series of 21 dogs and a cat that had hepatic and/or splenic target lesions noted during abdominal ultrasonography. Twelve of 16 hepatic target lesions and 5 of 7 splenic target lesions were malignant. In this series, the finding of one or more target lesions in the liver or spleen had a positive predictive value for malignancy of 74%; for the finding of multiple target lesions in one organ, the positive predictive value for malignancy was 81%. Benign lesions associated with target lesions were nodular hyperplasia of the liver and spleen, pyogranulomatous hepatitis, cirrhosis, and chronic active hepatitis.