IMAGING DIAGNOSIS—COMPUTED TOMOGRAPHIC,SURGICAL, AND HISTOPATHOLOGIC CHARACTERISTICS OF AN INFILTRATIVE ANGIOLIPOMA IN A DOG

A 6‐year‐old female spayed Shetland Sheepdog presented for evaluation of a subcutaneous mass over the right prescapular region. The mass had been cytologically diagnosed as a lipoma by the referring veterinarian 20 months prior, but had grown significantly and was very firm. CT scan of the mass was suggestive of neoplasia; however, the tissue of origin could not be determined. Histopathologic evaluation diagnosed infiltrative angiolipoma, and marginal resection of the tumor was performed. Infiltrative angiolipomas are benign but locally aggressive neoplasms uncommonly reported in veterinary medicine. This report correlates the clinical, CT, and histopathologic characteristics of an infiltrative angiolipoma.     

IMAGING DIAGNOSIS—ULTRASONOGRAPHIC APPEARANCE OF SKELETAL MUSCLE METASTASES IN A DOG WITH HEMANGIOSARCOMA

A 13‐year‐old spayed female German shepherd dog was presented for acute onset of lethargy, anorexia, and disseminated erythematous skin lesions. Thoracic radiographs and abdominal ultrasonographic findings were consistent with metastatic hemangiosarcoma. Multiple, ill‐defined, irregularly shaped hypoechoic nodules were also detected within the thoracic and abdominal wall. Hemangiosarcoma metastases to the skeletal muscle were confirmed based on histopathological examination. Multivisceral involvement was also confirmed by necropsy. Metastatic neoplasia should be considered as a differential diagnosis for dogs with ill‐defined, irregular, hypoechoic, intramuscular nodules.     

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.     

COMPUTED TOMOGRAPHIC FEATURES OF SUSPECTED TRAUMATIC INJURY TO THE ILIOPSOAS AND PELVIC LIMB MUSCULATURE OF A DOG

Computed-tomographic (CT) findings in a dog with acute suspected traumatic injury to the iliopsoas and neighboring pelvic musculature include enlargement of the affected muscles, multifocal intramuscular hypoattenuating areas, and nonuniform contrast enhancement of injured musculature. The CT features are postulated to be the result of intramuscular edema and inflammation, and correspond well to previously described ultrasonographic findings in dogs. Because of the close anatomic association between the femoral nerve and iliopsoas muscle, dogs with suspected iliopsoas injuries should be carefully evaluated for evidence of femoral nerve dysfunction. CT imaging may provide useful information regarding the nature and extent of iliopsoas muscular damage, as well as concurrent injuries in the actuely traumatized patient.     

RADIOGRAPHIC, COMPUTED TOMOGRAPHIC AND HISTOPATHOLOGIC APPEARANCE OF A PRESUMED SPINAL CHORDOMA IN A DOG

A 4-year-old Labrador Retriever presented for urinary incontinence and constipation of 2 weeks duration. There was a tender abdomen, lumbar pain and conscious proprioceptive deficits in both pelvic limbs. Depressed pelvic limb reflexes were present consistent with a lower motor neuron lesion. In radiographs of the lumbar spine there was narrowing of the intervertebral disc space at L5-L6 with irregular, multifocal areas of mineralized opacities dorsal to the intervertebral disc space, presumably within the vertebral canal. On computed tomography, an intramedullary, partially mineralized mass was identified in the spinal cord at the level of caudal L5 through cranial L6. At necropsy there was a four-centimeter enlarged, irregular segment of spinal cord at the level of L5-L6. When sectioned, the spinal cord bad a mineralized texture. Histologically there were variable sized cells that were stellate in appearance with vacuolated cytoplasm (physaliferous cells) and mucinous background consistent with a chordoma. Chordoma is a rare, skeletal neoplasm that originates from mesoderm-derived notochord and has been reported in humans and animals. Extraskeletal development of a chordoma within the spinal cord is a rare manifestation of this neoplasm. However, based on other reports in dogs, solitary extraskeletal locations of chordomas may be the typical expression of this neoplasm in the dog. Differentiation of similar histologically appearing tumors, such as a parachordoma or myxoid chondrosarcoma, will require immunohistochemical characterization of these tumors in veterinary patients.     

IMAGING DIAGNOSIS—ULTRASONOGRAPHIC DIAGNOSIS OF DIPLOMYELIA IN A CALF

We describe the ultrasonographic diagnosis of diplomyelia in a 40‐day‐old calf. The acoustic window was the lumbosacral junction, which, in cattle, corresponds to the L6–S1 intervertebral space and enables the evaluation of approximately 1 cm of the length of the spinal cord. Despite this limited length, this acoustic window yields good anatomic details and can be helpful in assessing anomalies of the caudal aspect of the spinal cord.     

RADIOGRAPHIC, COMPUTED TOMOGRAPHIC AND MAGNETIC RESONANCE IMAGING EVALUATION OF A CHRONIC LONG DIGITAL EXTENSOR TENDON AVULSION IN A DOG

Long digital extensor tendon avulsion is reported in a 5 month old Great Dane. Clinically the dog presented with a unilateral weight-bearing pelvic limb lameness. Joint effusion was present and there was pain and crepitance associated with flexion of the stifle. Orthopedic evaluation and radiographs were suggestive of a long digital extensor tendon injury which was confirmed by computed tomography and magnetic resonance imaging.The injury was surgically repaired with screw and spiked washer fixation.     

IMAGING DIAGNOSIS—SPINAL EPIDURAL HEMANGIOSARCOMA IN A DOG

An 8‐year‐old, male Boxer was examined for an acute onset of ambulatory paraparesis. Neurologic examination was consistent with a T3‐L3 myelopathy. Myelography revealed an extradural spinal cord compression in the region of the T10‐T13 vertebrae. On magnetic resonance (MR) imaging, a well‐defined epidural mass lesion was detected. The mass was mildly hyperintense on T1‐weighted, hyperintense on T2‐weighted and STIR images compared to normal spinal cord and enhanced strongly and homogenously. Postmortem examination confirmed a primary epidural hemangiosarcoma. Findings indicated that the MRI characteristics of spinal epidural hemangiosarcoma may mimic other lesions including meningioma and epidural hemorrhages/hematomas of non‐neoplastic etiology.     

IMAGING DIAGNOSIS—HETEROBILHARZIA AMERICANA INFECTION IN A DOG

An approximately three‐year‐old mixed breed female dog was evaluated for peritoneal effusion, anorexia, intermittent vomiting, and diarrhea. Radiographically, there was mineralization of the wall of small intestinal segments. Sonographic findings were consistent with multisystemic mineralization of liver, small intestinal wall, and pancreas. Multifocal granulomas containing schistosome eggs (Heterobilharzia americana) were identified histologically. The mineralization pattern described herein is an uncommon presentation of severe diffuse heterobilharziasis in a dog.     

IMAGING DIAGNOSIS—DISSEMINATED PERITONEAL LEIOMYOMATOSIS IN A DOG

A 17‐month‐old male Labrador retriever presented for evaluation of an abdominal mass felt during abdominal palpation. Multiple variably sized cystic masses were identified on sonographic and radiographic images. Exploratory laparotomy revealed multiple peritoneal masses that exhibited atypical contractions and lacked an identifiable organ of origin. Histology and immunohistochemistry of multiple surgically excised masses was consistent with benign tumors of smooth muscle origin (leiomyomas). The presence of multiple peritoneal leiomyomas in this dog is consistent with disseminated peritoneal leiomyomatosis. Two years after diagnosis and multiple surgical interventions, continual insidious enlargement of leiomyomas was identified on ultrasound and CT.     

IMAGING DIAGNOSIS—CONGENITAL LOBAR EMPHYSEMA IN A DOG

A 14‐week‐old female West Highland White Terrier developed acute dyspnea. Radiographically there was an enlarged, hyperlucent caudal portion of the left cranial lung lobe and a diffuse, severe interstitial‐to‐alveolar pattern in the remaining lung lobes that was accentuated caudodorsally. Computed tomography confirmed the presence of the emphysematous lobe and further showed it to have focal lobar bronchial collapse. Lung lobe resection was performed, and the diagnosis was congenital lobar emphysema secondary to bronchial cartilage hypoplasia.     

IMAGING DIAGNOSIS—THROMBOSED ORBITAL VARIX IN A DOG

A 9‐week‐old female Rhodesian Ridgeback presented with exophthalmos following minor blunt trauma to the left orbital area. Ocular ultrasound showed an extraconal retrobulbar mass ventromedial to the left globe. Magnetic resonance (MR) imaging demonstrated a thrombosed orbital vascular malformation without intracranial extension. Doppler ultrasound features of nonpulsatile slow flow were consistent with an orbital varix. Contrast‐enhanced dynamic time‐resolved and high‐resolution MR angiography demonstrated the varix arose from the anastomotic branch of the dorsal and ventral external ophthalmic veins. Conservative management led to a positive outcome defined as a visual eye and nearly normal cosmetic appearance at 8‐month follow‐up.     

IMAGING DIAGNOSIS—THE COMPUTED TOMOGRAPHIC APPEARANCE OF A GIANT CELL TUMOR AFFECTING THE MANDIBLE IN A PYGMY GOAT

A 3‐year‐old male neutered pygmy goat presented for evaluation of a progressive mandibular swelling and inappetence. A computed tomographic (CT) scan of the head and thorax was performed under general anesthesia. Computed tomography revealed an extensive multiloculated, markedly expansile lesion within the right hemimandible, which involved the articular surface of the temporomandibular joint. The goat was euthanased due to a poor prognosis and postmortem examination confirmed the diagnostic imaging findings. Histopathology was strongly suggestive of a multinucleated giant cell tumor, therefore this condition should be considered as a differential diagnosis in goats presenting with expansile mandibular mass lesions.     

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.     

IMAGING DIAGNOSIS—MAGNETIC RESONANCE IMAGING FEATURES OF A CEREBRAL HEMANGIOBLASTOMA IN A DOG

The magnetic resonance (MR) imaging features of a cerebral hemangioblastoma in a 9‐year‐old dog are described. Imaging revealed a well‐defined contrast‐enhancing lesion of the rostral forebrain that appeared extraparenchymal. Histopathology of the excised mass showed clusters of small blood vessels interspersed with interstitial cells staining positive for neuronal specific enolase, features consistent with a cerebral hemangioblastoma; the mass also appeared intraparenchymal after further immunohistochemistry study. This neoplasm should be considered a rare differential diagnosis for intracranial masses in dogs.     

COMPUTED TOMOGRAPHY AND MAGNETIC RESONANCE IMAGING OF CAVERNOUS SINUS ENLARGEMENT IN A DOG WITH UNILATERAL EXOPHTHALMOS

Computed tomography (CT), magnetic resonance imaging (MRI) and magnetic resonance angiography (MRA) were performed on a dog with a two year history of unilateral exophthalmos occurring two years following head trauma. On CT images, an expansile enhancing mass was present along the right intracranial cavernous sinus and extended through the orbital fissure into the retrobulbar space. With MRI, the structure appeared as a signal void due to the presence of rapidly flowing blood. Gadolinium enhancement of the adjacent brain was not present. A vascular origin of the lesion was confirmed with MRA. Based on the CT and MRI findings, the enlarged cavernous sinus and associated ophthalmic plexus were believed to represent an arterialized aneurysm, most likely the result of traumatic arteriovenous fistulization. Treatment consisted of surgical enucleation. At the time of this report, 29 mouths later, the dog remains free of clinical signs.     

IMAGING DIAGNOSIS—COMPUTED TOMOGRAPHY FINDINGS IN A DOG WITH SPONTANEOUS TRANSMURAL MIGRATION OF A TEXTILOMA INTO THE CECUM

A 3‐year‐old spayed female dog was presented with 3‐month history of severe bilateral uveitis subsequent to previous ovariohysterectomy. Physical examination revealed moderate abdominal pain. Computed tomography showed a nonobstructive heterogeneous mass‐like lesion with a speckled gas pattern (spongiform pattern) within the cecum. Exploratory laparotomy revealed a surgical swab in the lumen of the cecum with severe adhesions. Histopathological examination demonstrated a chronic inflammatory pyogranulomatous reaction to the retained swab embedded within the intestinal wall, consistent with transmural migration of the swab from the peritoneal cavity into the cecum.     

LOW-FIELD MAGNETIC RESONANCE IMAGING OF A PYOCEPHALUS AND A SUSPECTED BRAIN ABSCESS IN A GERMAN SHEPHERD DOG

Magnetic resonance imaging was performed on an eight-year-old, neutered female German Shepherd dog with a history of acute depression, inappetence, and hyperthermia. A lesion in the cerebrum was suspected. Possible differential diagnoses were meningoencephalitis, neoplasia, and vascular lesion (infarction, bleeding). A ring enhancing lesion was found in the basal ganglia on the left side with edema of the surrounding brain tissue. A similar mass lesion was present in the right pterygoid musculature. With inversion recovery sequences an altered composition of the cerebrospinal fluid (CSF) in the left lateral ventricle could be detected. CSF analysis confirmed a pyocephalus, probably due to rupture of a brain abscess into the left lateral ventricle.     

IMAGING DIAGNOSIS—USE OF MULTIPHASIC CONTRAST‐ENHANCED COMPUTED TOMOGRAPHY FOR DIAGNOSIS OF MESENTERIC VOLVULUS IN A DOG

A 4‐year‐old German shorthaired pointer presented with collapse and hematochezia. Radiographs showed gas and fluid‐distended small intestines and loss of serosal detail. Ultrasound examination showed hypomotile, fluid‐distended small intestines, and thrombosed jejunal veins. Multiphasic contrast‐enhanced computed tomography was performed and showed a CT “whirl sign,” an important but nonspecific sign of intestinal volvulus in human patients. At surgery, the majority of the small intestine was entangled in the volvulus and showed black discoloration. The patient was euthanized. Postmortem evaluation yielded a diagnosis of jejunoileal mesenteric volvulus secondary to a congenital omphalomesenteric duct remnant.