ULTRASONOGRAPHIC EXAMINATION OF THE PHARYNX AND LARYNX OF THE NORMAL DOG

Real-time ultrasonographic examination of the canine larynx was performed in 12 normal dogs using a 7.5-mHz mechanical sector scanner combined with a stand-off. A variety of breeds and ages were examined. All examinations were performed in nonsedated, conscious animals. Transverse scans were found to provide the most reliable and interpretable images. Identification of laryngeal structures included the epiglottis, laryngeal and cricoid cartilages, and the vocal cords. In conscious animals, abduction and adduction of the vocal cords associated with respiration could be identified if the animal was made to pant during the examination. Movement of the vocal cords could also be quantified by pulse-wave Doppler recording. In all animals, recordings were made during inspiration only, with muscular vibration at a rate less than 0.1 m/s.     

MAGNETIC RESONANCE IMAGING ANATOMY OF THE NORMAL EQUINE LARYNX AND PHARYNX

The purpose of the present study was to describe normal magnetic resonance (MR) imaging anatomy of the equine larynx and pharynx and to present the optimal protocol, sequences, and possible limitations of this examination technique. Using a 0.3 T unit, the laryngeal and pharyngeal regions was imaged in two horses. The protocol consisted of sagittal and transverse T2-weighted (T2w) fast spin echo, transverse T1-weighted (T1w) spin echo, and dorsal high-resolution T1w gradient echo (both pre- and postcontrast enhancement) sequences. Euthanasia was performed at the end of the imaging procedure. Macroscopic anatomy of the cadaver sections were compared with the MR images in transverse, midsagittal, and parasagittal planes. There was good differentiation of anatomic structures, including soft tissues. The laryngeal cartilages, hyoid apparatus, and upper airway muscle groups with their attachments could be clearly identified. However, it was not always possible to delineate individual muscles in each plane. Most useful were both T2w and T1w transverse sequences. Intravenous application of contrast medium was helpful to identify blood vessels. The MR images corresponded with the macroscopic anatomy of cadaver sections.     

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.     

COMPUTED TOMOGRAPHY OF THE PHARYNX IN A CLOSED VS. OPEN MOUTH POSITION

The pharynx is anatomically complex and evaluation can be difficult even with cross‐sectional imaging. Eight animals had computed tomography (CT) studies of the head performed with the mouth open and closed. The studies were anonymized and evaluated by four radiologists for visibility of six anatomic regions (dorsal wall of nasopharynx, lumen of nasopharynx, dorsal margin of the soft palate, ventral margin of the soft palate, oropharynx, and laryngopharynx) and for certainty of a normal or abnormal diagnosis of four different anatomic regions (nasopharynx, soft palate, oropharynx, and laryngopharynx). Mean visual scores differed significantly between mouth positions and were improved when the mouth was open. The ability of radiologists to classify anatomic regions as normal or abnormal vs. unsure also varied between mouth positions, and there was greater uncertainty when the mouth was closed. In addition, estimated volume of the air‐filled nasopharynx differed significantly as a function of mouth position and was greater when the mouth was open (mean=1.187 cm³, SE=0.177) vs. closed (mean=0.584 cm³, SE=0.116). Computed tomographic evaluation of the pharynx can be improved with the mouth open.     

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.     

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.     

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.     

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.     

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.     

OSSEOUS METAPLASIA IN THE RENAL PELVIS OF A DOG WITH HYDRONEPHROSIS

A 3-year-old male Sheltie dog was presented with abdominal distension, diarrhea, and vomiting. Hematologic and blood chemistry studies revealed a mild anemia and a few leukocytes in the urine. Radiographic examination was made, and a large mass with calcified trabeculae was present in the ventral right cranial quadrant of the abdomen. Exploratory celiotomy was performed, and a mass identified as the right kidney was removed. The excised kidney was cystic and multiloculated, and contained areas of bone and cartilage. This mass weighed 1120 g and was in excess of ten percent of the dog's body weight. Transitional epithelium can stimulate osseous metaplasia. The presence of both tissues in a biopsy specimen might indicate urinary tract disease.     

APPROACHES FOR ULTRASONOGRAPHIC EVALUATION OF LONG BONES IN THE DOG

The objective of this study was to identify access portals for ultrasonographic evaluation of canine long bones (humerus, radius, ulna, femur, and tibia). A 7.5 MHz linear transducer was used in five medium-sized dogs (range of 25-35 kg body weight). Good approaches could be identified for all long bones. For the proximal humerus, a cranial portal, and the distal humerus, a lateral portal is suggested. For the radius and ulna, a craniolateral approach seemed to be the best. In the hindlimb, a medial approach for the femur and a craniolateral approach for the tibia were the most effective approaches.     

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.     

THE EFFECT OF POSITIONING ON THE RADIOGRAPHIC APPEARANCE OF CAUDODORSAL MEDIASTINAL MASSES IN THE DOG

In this prospective study, the effect of thoracic positioning on the visibility and size of caudal esophageal masses caused by spirocercosis was investigated. Dorsoventral (DV), ventrodorsal (VD) as well as left lateral recumbent (LLR) and right lateral recumbent (RLR) thoracic radiographs of 28 dogs, diagnosed endoscopically with spirocercosis, were evaluated. The radiographic findings were compared with those of esophageal endoscopy. Masses were seen equally well in left vs. right recumbency as well as in DV vs. VD positions but in DV/VD views 86% of masses were detected whereas in lateral views only 50% of masses were identified. In spirocercosis-endemic areas DV and RLR views are advised as they also allow for better visualization of descending aorta aneurysms and to avoid interpreting the potentially normally visible esophagus in LLR in large dogs as a mass.     

MAGNETIC RESONANCE IMAGING OF OCULAR AND ORBITAL DISEASE IN 5 DOGS AND A CAT

Magnetic resonance (MR) images were acquired in five dogs and one cat with ocular and orbital disease. MR images were obtained in the dorsal or oblique dorsal, and oblique sagittal planes. Pathologic changes identified in MR images included inflammatory lesions, cystic structures, and neoplasms. All abnormalities were readily apparent in TI-weighted images. MR findings in affected animals were often similar in signal intensity, location, and growth pattern to those found in people with comparable diseases. Although no MR changes were considered pathognomonic for a given disease, MR imaging provided detailed information on the homogeneity, extent and invasiveness of the lesions.     

SONOGRAPHY OF THE MUSCULOSKELETAL SYSTEM IN DOGS AND CATS

Sonography of the musculoskeletal system in dogs and cats was undertaken to evaluate the application of this imaging procedure in orthopedics. In most of the patients a 7,5 MHz linear transducer was used because of its flat application surface and its resolving power. The evaluation of bone by sonography is limited, but sonography can provide addition information regarding the bone surface and surrounding soft tissue. Ultrasound is valuable for assessing joint disease. Joint effusion, thickening of the joint capsule and cartilage defects can be identified sonographically. It is also possible to detect bone destruction. Instabilities are often identified with the help of a dynamic examination. Soft tissue abnormalities of the musculoskeletal system lend themselves to sonographic evaluation. Partial or complete muscles or tendon tears are able to be differentiated and the healing process can be monitored. Most of the diseases that are in the area of the biceps or the achilles tendon, such as dislocation of the tendon, old injuries with scarification, free dissecates in the tendonsheath, tendinitis and/or tendosynovitis can be differentiated by sonography. In addition, with clinical and laboratory findings, it is often possible to make a correct diagnosis with ultrasound in patients with abscesses, foreign bodies, hematomas, soft tissue tumors and lipomas.     

RADIOGRAPHIC AND COMPUTED TOMOGRAPHIC CHANGES AND CLINICAL PRESENTATION OF SPIROCERCOSIS IN THE DOG

A retrospective study of 39 dogs with spirocercosis is described, emphasizing radiographic and computed tomographic aspects and clinical presentation. Dogs were classified as complicated or uncomplicated, both clinically and radiographically. Besides the expected upper gastrointestinal signs, a high incidence of respiratory (77%) and locomotor (23%) complications were present. All dogs had thoracic radiographs. Esophageal masses were radiographically classified as typical or atypical according to their location. Twenty-seven dogs had a typical caudal esophageal mass. Six dogs had a mass atypically located in the hilar region. These masses were smaller and more difficult to visualize radiographically. The remaining 6 dogs did not have a radiographically detectable esophageal mass. Radiology as an initial diagnostic tool was effective in detecting and localizing the mass and to detect early respiratory abnormalities such as pleuritis, mediastinitis, pneumonia, and bronchial displacement. Endoscopy was the modality of choice to confirm antemortem esophageal masses. In dogs where the mass filled the whole esophageal lumen, endoscopy failed to give essential information necessary for surgical excision of neoplastic masses, such as the extent of esophageal wall attachment. Caudal esophageal sphincter involvement was difficult to determine endoscopically with large caudal esophageal masses. Computed tomography was performed on 3 dogs and did not address the latter problems completely, but was found to be a sensitive tool to detect focal aortic mineralization and early spondylitis, both typical for the disease, and essential in the diagnosis of non- or extramural esophageal abnormalities.     

THE EFFECT OF PREPUBERAL AND POSTPUBERAL GONADECTOMY ON PENILE EXTRUSION AND URETHRAL DIAMETER IN THE DOMESTIC CAT

Male (n = 6/group) and female (n = 6/group) kittens were gonadectomized at 7 weeks or 7 months of age, or left intact. At 22 months of age, complete penile extrusion was possible in all of the intact males, in 3/5 (60%) males castrated at 7 months of age, and in none of the males castrated at 7 weeks of age. Antegrade (voiding) cystourethrograms were performed at 22 months of age. Diameter of the preprostatic (p = 0.13) and penile (p>0.25) urethra of male cats did not vary by group. Diameter of the pre-pelvic urethra of female cats gonadectomized at 7 weeks of age was significantly smaller than that of intact females (p = 0.02).     

RADIOGRAPHIC AND ULTRASONOGRAPHIC FEATURES OF RETAINEDSURGICAL SPONGE IN EIGHT DOGS

The radiographic and ultrasonographic signs in eight dogs with a surgical or pathologic diagnosis of retained surgical sponge were reviewed. The most frequent previous surgery was ovariohysterectomy, either as an elective procedure or to treat pyometra. The median elapsed time between surgery and diagnosis of retained surgical sponge was 9.5 months (range 4 days to 38 months). Five dogs had a draining sinus; four had a palpable abdominal mass. Radiologic signs included localized, speckled or whirl-like gas lucency, abdominal mass, and non-focal soft tissue swelling. Survey radiography and sinography were considered diagnostic for retained surgical sponge in 4/7 (57%) and 3/5 (60%) dogs, respectively. The combined use of survey radiography and sinography enabled detection of 6/7 (86%) sponges. In each dog that had ultrasonography, a hypoechoic mass was found that had an irregular hyperechoic centre. The possibility of retained surgical sponge should be considered in animals with a history of previous surgery and a sinus or abdominal mass.     

EFFECT OF CONTRAST MEDIUM DOSE AND IMAGE ACQUISITION TIMING ON URETERAL OPACIFICATION IN THE NORMAL DOG AS ASSESSED BY COMPUTED TOMOGRAPHY

Computed tomography (CT) excretory urography was performed in five adult female dogs after intravenous injection of a bolus of four different doses of water-soluble iodinated contrast medium (100, 200, 400, and 800 mg1/kg). CT images centered over the urinary bladder were performed before injection and 1,3,5,7,9,11,15,20,25,30,40,50, and 60 minutes after injection. Opacification of both ureters was evaluated by measuring maximum CT number of individual ureters at each time. Time opacification curves were generated for each dose. Best opacification of the ureters was obtained with 400 and 800 mgl/kg, with a constant peak at 3 minutes and durable opacification for 1 hour. Insufficient opacification was obtained with lower dose of 100 and 200 mgI/kg.