Diagnosis of renal agenesis in a beagle.

A case of right renal agenesis in a beagle, of interest because of the age of the dog at the time of diagnosis, is described. Physical, haematological, biochemical and urinary examinations, including measurement of endogenous creatinine clearance, were performed to assess renal function. Survey radiography, excretory urography, ultrasonography, computed tomography and nuclear magnetic resonance examinations were also used to confirm the absence of a kidney. The effect of kidney agenesis on renal function, evaluated on the basis of endogenous creatinine clearance, is discussed together with the benefits of the various imaging techniques to enable in vivo detection of renal abnormalities.     

Computed tomographic and magnetic resonance imaging features of canine segmental caudal vena cava aplasia

O bjective : To describe the computed tomographic and magnetic resonance imaging features of segmental caudal vena cava aplasia and associated vascular anomalies in dogs.
M ethods : A retrospective study was performed reviewing computed tomographic and magnetic resonance imaging archives of eight institutions for dogs with segmental caudal vena cava aplasia. Inclusion criteria included a computed tomographic or magnetic resonance imaging study and supportive diagnostic and follow-up information. Abdominal vessels were reviewed for size, shape, location and course (including tributaries and branches) and classified as normal, abnormal or shunt vessels.
R esults : Ten dogs with segmental caudal vena cava aplasia were identified. In all dogs, postrenal caval blood was shunted to either a right or a left azygos vein, with seven different angiographic patterns. Affected dogs were predominantly female (70 per cent) and young (mean 2·6 years). Additional portocaval and porto-azygos shunt vessels were identified in two cases each. Computed tomographic angiography and magnetic resonance angiography depicted details of abdominal vessels including thrombus formation in one dog.
C linical S ignificance : Segmental caudal vena cava aplasia is a vascular congenital anomaly in the dog that can be associated with thrombosis and portosystemic shunts. Computed tomographic angiography and magnetic resonance angiography are excellent tools to demonstrate the complex vascular anatomy and to guide treatment planning for portosystemic shunts and thrombolytic therapy.     

MULTIPLE CONGENITAL URINARY TRACT ABNORMALITIES IN A BITCH: A CASE HISTORY REPORT

A 2 1/2-month-old, female German Shepherd Dog was examined because of incontinence since birth. Multiple urinary anomalies which included left renal agenesis, right hydronephrosis and hydroureter and urinary bladder dysfunction were found by excretory urography. These abnormalities were confirmed at necropsy. In addition, vesicovaginal continuity with apparent absence of the urethra was also found     

Unilateral renal agenesis associated with additional congenital abnormalities of the urinary tract in a Pekingese bitch

An eight-month-old Pekingese bitch with urinary incontinence was found to have three congenital anomalies of the urinary tract: left renal agenesis, bilateral ectopic ureters with a left cranial blind-ending ureter, and urinary bladder hypoplasia. The diagnoses were made by retrograde vaginourethrography, excretory urography, ultrasonography and duplex Doppler ultrasonography. Although urological anomalies associated with renal agenesis have been frequently observed, a cranial blind-end ectopic ureter has not, to the authors' knowledge, been described in the bitch. The dog was managed medically with a restricted protein diet because of a compromised unilateral kidney with hydronephrosis and hydroureter.     

Post mortem magnetic resonance imaging of multiple congenital ocular anomalies in a Comtois mare

Multiple congenital ocular anomalies syndrome consists of several abnormalities mainly localised to the anterior segment of the eye. This condition, comprising iridal or ciliary cysts with or without iridal hypoplasia, an excessively protruding cornea (‘cornea globosa’), miotic pupils, retinal dysplasia, cataract, and other lesions, has been reported in several breeds and is strongly related to the silver coat colour, as a result of a dominant mutant allele at the PMEL17 locus. This report describes the macroscopic, ultrasonographic, histological and magnetic resonance imaging findings of the ocular abnormalities in a Comtois mare with multiple congenital ocular anomalies syndrome.     

CONTRAST‐ENHANCED PORTAL MAGNETIC RESONANCE ANGIOGRAPHY IN DOGS WITH SUSPECTED CONGENITAL PORTAL VASCULAR ANOMALIES

Contrast‐enhanced multiphase magnetic resonance angiography (CE‐MRA) was used in 17 dogs with a suspected congenital portal vascular anomaly. Portal vascular anomalies were identified in 16 of the 17 dogs. Eleven had a single intrahepatic portocaval shunt (two central divisional, three right divisional, and six left divisional), one dog had a double intrahepatic portocaval shunt, one dog had a hepatic arteriovenous malformation, one dog had a complex intrahepatic porto‐caval shunt. Two dogs had an extrahepatic portosystemic shunt and no shunt was identified in one dog. Total imaging time was <10 min and image quality was good to excellent in all dogs. Portal CE‐MRA is a feasible, fast and non invasive technique to diagnose portal vascular anomalies in dogs, with a large field‐of‐view and good anatomic depiction of the abnormal vessels. Based on these results, CE‐MRA is an efficient imaging technique for the diagnosis of portal vascular anomalies in dogs.     

Nonneoplastic disorders of the brain.

Computed tomography (CT) and magnetic resonance imaging (MRI) are helpful in the diagnosis of many nonneoplastic brain disorders in the dog and cat. The ability of CT and MRI to depict normal and abnormal anatomy facilitates the identification of developmental anomalies, including hydrocephalus, Chiari malformations, arachnoid cysts, and cerebellar hypoplasia. These imaging modalities also allow the detection of hemorrhage and infarction and are therefore useful in the evaluation of spontaneous cerebrovascular disorders and head trauma. Finally, many inflammatory diseases, such as encephalitis, brain abscess, and parasite migration, cause abnormalities detectable by CT and MRI. Although more research on the imaging features of specific nonneoplastic brain disorders is needed, current information indicates that CT and MRI are useful in the management of these disorders.     

Spinal dermoid sinus in a Burmese cat with paraparesis

A 2-year-old, male, Burmese cat was evaluated for chronic progressive hindlimb weakness, ataxia and urinary incontinence. Radiographic examination, myelography and magnetic resonance imaging defined congenital vertebral anomalies and a space-occupying intradural, extramedullary mass. A dermoid sinus was subsequently identified dorsal to the affected spine. Surgical excision of the tract necessitated a dorsal laminectomy and removal of a 1-cm diameter intradural dermoid sinus 'cyst' that contained hair and sebaceous debris. The cat recovered hindlimb function after surgery and remains asymptomatic 50 months after surgery except for a persistent inability to urinate voluntarily.     

Magnetic resonance and computed tomographic features of 4 cases of canine congenital thoracic vertebral anomalies

Magnetic resonance and computed tomography features of 4 cases of canine congenital vertebral anomalies (CVAs) are discussed. Two of the cases represent unusual presentations for such anomalies that commonly affect screw-tail or toy breeds. Moreover, the combination of CVAs and a congenital peritoneo-pericardial diaphragmatic hernia has never before been imaged.     

Suspected protozoal myeloencephalitis in a two-month-old colt

A two-month-old Appaloosa colt developed neurological signs shortly after birth involving deficits affecting cranial nerves IV, VII, VIII, IX, X and XII, and possibly nerve VI. The most likely differential diagnoses were congenital anomalies, meningoencephalitides, trauma or nutritional causes. The foal was investigated by the analysis of cerebrospinal fluid (CSF), electromyelography (EMG), brain auditory evoked responses, magnetic resonance imaging (MRI), peripheral nerve biopsy, and Western blot analysis for the presence of intrathecal antibodies to Sarcocystis neurona, the causative agent of equine protozoal myeloencephalitis. Significantly abnormal EMG findings included spontaneous electrical activity of the tongue, suggesting denervation. The MRI was useful in ruling out masses, congenital anomalies and focal abscessation. The cytology of CSF revealed mild mononuclear reactivity. Western blot testing of CSF was positive, indicating the intrathecal presence of antibodies to S neurona. The foal was treated with pyrimethamine and trimethoprim-sulphadiazine for two months and returned to nearly normal neurologic status.     

MULTIPHASE TIME-RESOLVED CONTRAST-ENHANCED PORTAL MRA IN NORMAL DOGS

Portal vein anomalies are common in dogs and cats. Diagnostic imaging is central in their diagnosis and fundamental with regard to choosing the best therapeutic option. Various imaging techniques are used in veterinary medicine to assess the portal vein. Each has individual advantages and disadvantages. Contrast-enhanced magnetic resonance angiography (CE-MRA) is used routinely in humans to image the portal system and has excellent spatial and temporal resolution and three-dimensional (3D) acquisition. Herein, we report the development of a CE-MRA protocol that resulted in fast 3D imaging of the arterial splanchnic and portal venous system in normal dogs. Multiphase acquisition strategy allowed acquiring the same volume several times during one single breath-hold, thereby capturing the portal venous phase with excellent signal. Excellent depiction of the vascular anatomy, especially the portal afferent vessels and branches, was observed. Elliptical centric view ordering of k-space was used to acquire the contrast-sensitive data faster. Parallel imaging was used to increase coverage in the dorsal to ventral direction while keeping imaging time short. It is anticipated that 3D CE-MRA is a fast and noninvasive imaging method that could be used to diagnose various portal vascular anomalies in small animals.     

Magnetic resonance imaging of selected limb joints in dogs

The presented paper presents updated information concerning magnetic resonance imaging (MRI) of shoulder joint, elbow joint and knee joint in dogs. It describes indications, planes, standard sequences, slice thickness to perform MRI examination of above mentioned joints. Besides general information about basic physics use in magnetic resonance imaging, and practical information about magnetic resonance and it usage in orthopedic examination are given.     

Urography in the Dog by an Intravenous Transfusion Technique

Abstract— —A technique of intravenous urography is described which allows more kidney detail to be demonstrated than with conventional intravenous excretion methods. Its possible value in conditions where other routine methods of contrast urography are not effective or are impracticable is also discussed.     

Comparison of radiography and magnetic resonance imaging for evaluating the extent of nasal neoplasia in dogs

OBJECTIVES: Magnetic resonance imaging (MRI) is increasingly used in veterinary practice and, in some centres, is part of the diagnostic work-up of small animals with nasal disease. However, there are no published studies which critically evaluate the use of magnetic resonance imaging for this purpose. The purpose of this work was to assess the changes seen using magnetic resonance imaging and to compare them with radiography. METHODS: The study included 12 dogs that had undergone both radiography and magnetic resonance imaging of the nasal cavity and had a histopathological diagnosis of malignant nasal neoplasia. Two pairs of board-certified radiologists scored the radiographs and the MRI scans, evaluating 10 signs of abnormality using a simple scoring system. Magnetic resonance imaging features were described in detail, and radiographic and magnetic resonance imaging scores for each sign as well as total scores were compared. RESULTS: Magnetic resonance imaging often showed that the tumour was more extensive than it had appeared on radiography but occasionally showed that radiographs had overestimated its size. Although radiography was reliable for assessment of the presence and size of a mass and for the extent of turbinate destruction, it usually failed to show occlusion of the major airway passages that were evident on magnetic resonance imaging. Extension of the tumour into the opposite nasal cavity, frontal sinus, orbit and cranial cavity was shown much better on magnetic resonance imaging. CLINICAL SIGNIFICANCE: Minor but significant extension beyond the nasal cavity, which is important for treatment planning and prognosis, requires magnetic resonance imaging for demonstration, although radiography shows major changes reliably.     

Dysplasia of the caudal vertebral articular facets in four dogs: results of radiographic, myelographic and magnetic resonance imaging investigations

Congenital anomalies of the vertebral column associated with aberrations of one of the primary vertebral ossification centres have been frequently described in the veterinary literature, but clinically significant abnormalities of secondary vertebral ossification centres, particularly involving the caudal articular processes, are much less frequently reported. This paper describes three dogs with aplasia and one dog with hypoplasia of the caudal vertebral articular processes. Thoracolumbar spinal cord compression and ataxia was evident in the three dogs with aplasia but no clinical signs were evident in the dog with hypoplasia. The radiographic appearance was similar in all four cases, with aplasia or hypoplasia of the caudal articular facets at one or more intervertebral joints in the thoracolumbar region. Bone proliferation was evident secondary to an associated degenerative joint disease. Compensatory hyperplasia of the adjacent cranial articular facets and ligamentum flavum protruded into the vertebral canal, resulting in a compressive myelopathy observed by myelography and magnetic resonance imaging.     

Contrast-enhanced magnetic resonance angiography of patent ductus arteriosus in a dog

Gadolinium-enhanced three-dimensional magnetic resonance angiography is a relatively new technique in the veterinary field. A mature dog with suspected patent ductus arteriosus underwent contrast-enhanced magnetic resonance angiography at 1·0 T with a three-dimensional fast low-angle shot (FLASH) gradient-echo technique. Qualitatively, three-dimensional images of the ductus were particularly clear with surface reconstructions, and ductus diameters were easy to assess in native images. Contrast-enhanced magnetic resonance angiography is a fast, relatively non-invasive procedure that could be particularly useful when non-surgical interventional procedures are anticipated for ductus occlusion.     

Initial Experience Using Contrast Magnetic Resonance Imaging in Laminitic Horses: 18 Studies

Plain radiographic imaging inadequately identifies soft-tissue pathology and only distinguishes chronic laminitis after the development of notable displacement of the distal phalanx. The window of opportunity for maximum response to treatment occurs before biomechanical failure of the lamellar attachment. Radiographic and magnetic resonance venograms allow vascular assessment of patients affected with acute laminitis. When vascular findings are interpreted with additional magnetic resonance information, the degree of damage to the foot in patients affected with laminitis is understood more thoroughly. This article describes the technique, findings, and outcome in a group of laminitic horses that underwent contrast magnetic resonance imaging.     

Comparison of computed tomography and magnetic resonance imaging for the evaluation of canine intranasal neoplasia

O bjectives : Canine intranasal neoplasia is commonly evaluated using computed tomography to indicate the diagnosis, to determine disease extent, to guide histological sampling location and to plan treatment. With the expanding use of magnetic resonance imaging in veterinary medicine, this modality has been recently applied for the same purpose. The aim of this study was to compare the features of canine intranasal neoplasia using computed tomography and magnetic resonance imaging.
M ethods : Twenty-one dogs with confirmed intranasal neoplasia underwent both computed tomography and magnetic resonance imaging. The images were reviewed retrospectively for the bony and soft tissue features of intranasal neoplasia.
R esults : Overall computed tomography and magnetic resonance imaging performed very similarly. However, lysis of bones bordering the nasal cavity and mucosal thickening was found on computed tomography images more often than on magnetic resonance images. Small amounts of fluid in the nasal cavity were more often seen on magnetic resonance images. However, fluid in the frontal sinuses was seen equally well with both modalities.
C linical S ignificance : We conclude that computed tomography is satisfactory for evaluation of canine intranasal neoplasia, and no clinically relevant benefit is gained using magnetic resonance imaging for intranasal neoplasia without extent into the cranial cavity.     

IMAGING FEATURES OF ATLANTO-OCCIPITAL OVERLAPPING IN DOGS

The imaging features of four dogs with atlanto-occipital overlapping are described. This malformation appeared to play a role in the development of neck pain, ataxia, variable cerebellar involvement, medullary kinking, and possibly syringomyelia. Using cervical radiographs, three of the four dogs were initially diagnosed with an atlanto-axial malformation. Because this disorder could not account for all clinical signs, magnetic resonance and computed tomography images were also acquired. These provided a more complete evaluation of the craniocervical junction, allowing detection of atlanto-occipital overlapping, medullary kinking, occipital dysplasia, abnormalities of the dens, and syringomyelia in these dogs. Head position during imaging affected the degree of atlanto-occipital overlap. These findings emphasize the need to modify the currently accepted imaging recommendations for dogs with head and neck pain and/or cranial cervical myelopathy. We suggest that the entire craniocervical junction be evaluated, even if atlanto-axial subluxation has already been detected. Moreover, we propose that atlanto-occipital overlapping is a perhaps underrecognized disorder that can influence the clinical signs and therapeutic outcome of dogs with anomalies of the craniocervical junction.     

LOW FIELD MAGNETIC RESONANCE IMAGING CHARACTERISTICS OF CRANIAL VAULT MENINGIOMAS IN 13 DOGS

Meningiomas are common intracranial masses in the dog, and surgical or radiation treatment of meningiomas depends on accurate identification and location. In this review of 13 patients with confirmed meningioma, low field magnetic resonance imaging characteristics of cranial vault meningiomas included increased signal intensity on T2-weighted images, decreased signal intensity on T1-weighted images, and marked contrast enhancement that was usually nonhomogeneous and well-defined. Mass effect and edema were usually present. Cyst formation and meningeal enhancement were also found in some patients. Low field magnetic resonance imaging characteristics of the meningiomas in these patients were similar to those magnetic resonance imaging findings reported in humans and the few reports pertaining to animals.