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Constrictive myelopathy has been described in pugs with paraparesis and is characterized by fibrous connective and granulation tissue within the dura mater causing spinal cord compression and focal gliosis. An association between constrictive myelopathy and caudal articular process (CAP) dysplasia is suspected; however, some studies have reported CAP dysplasia as an incidental finding. The imaging appearance of constrictive myelopathy is currently limited to a small number of cases. The aim of this multicenter, retrospective, descriptive study was to detail the magnetic resonance imaging (MRI) characteristics and to correlate these with clinical signs of presumptive constrictive myelopathy in pugs. Medical databases from five veterinary referral hospitals were reviewed to identify pugs with pelvic limb ataxia and paresis, that had a complete record of signalment, neurological examination, and MRI of the thoracolumbar spinal cord. The exclusion criteria were pugs with other conditions, such as unequivocal subarachnoid diverticula, hemivertebrae causing vertebral canal stenosis, intervertebral disc extrusions/protrusions, and multifocal/diffuse lesions. Twenty-seven pugs met the inclusion criteria. All cases were ambulatory with paraparesis and ataxia. Nearly 60% were incontinent. Magnetic resonance imaging revealed a focal myelopathy in all cases showing one or more of the following lesions: CAP dysplasia (25/27), focal subarachnoid space irregular margination (26/27) with circumferential or dorsal contrast enhancement (10/12), and a symmetric V-shaped ventral extradural lesion (23/27). This study describes specific MRI features of pugs with presumptive constrictive myelopathy, which authors hypothesize to be a consequence of chronic micro-motion. Our results may help in diagnosing and subsequently treating this condition, which may warrant vertebral stabilization.

Eosinophilic bronchopneumopathy is a disease characterized by the infiltration of the lung and bronchial mucosa by eosinophils. The aim of the present study was to describe the CT findings in a large series of dogs with confirmed diagnosis of eosinophilic bronchopneumopathy. Computed tomographic scans of 15 dogs with confirmed diagnosis of eosinophilic bronchopneumopathy were evaluated retrospectively by two boarded radiologists who reached a consensus. Abnormalities were identified in 14/15 (93%) dogs, including pulmonary parenchymal abnormalities in 14/15 (93%) dogs, bronchial wall thickening in 13 (87%) dogs, which was considered marked in eight (53%), plugging of the bronchial lumen by mucus/debris in 11 (73%) dogs, and bronchiectasis in nine (60%) dogs. Pulmonary nodules were identified in 5/15 (33%) dogs including one dog with a mass. All dogs with a nodular lung pattern had additional abnormalities. Lymphadenopathy was present in 10 dogs (67%). Lesions associated with eosinophilic bronchopneumopathy are variable and heterogeneous and encompass a wider variety of computed tomographic features than reported previously. Computed tomographic images were abnormal in the majority of affected dogs, hence CT is a useful modality to characterize the nature and distribution of thoracic lesions in dogs with eosinophilic bronchopneumopathy.

Computed tomography (CT) is an established technique for detecting shoulder lesions in dogs, however the clinical significance of shoulder CT lesions often remains uncertain. The purposes of this retrospective study were to describe the prevalence of CT lesions in both shoulder joints for 89 dogs presenting with thoracic limb lameness and to compare CT lesions with clinical characteristics. For all included dogs, results of a full orthopedic examination, other diagnostic tests, and signalment data were available in medical records. Multilevel, multivariable logistic regression was used to test clinical significance of the most prevalent CT lesions and determine factors associated with their presence. Computed tomographic lesions were detected in one or both shoulder joints for 51/89 dogs (57.3%). Mineralization of one or more surrounding peri-articular soft-tissue structures was identified in 31.5% of dogs, with supraspinatus muscle/tendon mineralization being the most frequently identified (24.7%). The prevalence of humeral head osteochondrosis was 9 and 21.3% of dogs had shoulder osteoarthritis. Border collies (odds ratio [OR] 9.3; 95% CI 1.39-62.1, P = 0.02) and dogs with shoulder pain (OR 4.3; 95% CI 1.08-17.1, P = 0.04) had increased risk of osteochondrosis lesions. Border collies (OR 8.4; 95% CI 1.27-55.6; P = 0.03) and older animals (OR 1.04; 95% CI 1.02-1.1, P < 0.001) had increased risk of osteoarthritis lesions. Female entire dogs had an increased risk of supraspinatus mineralization lesions (OR 6.8; 95% CI 1.55-29.5, P = 0.01). Findings indicated that shoulder CT lesions are common in dogs with thoracic limb lameness, and that some CT lesions are not associated with shoulder pain.

MRI is a cross-sectional imaging modality, which uses the spins of hydrogen protons to generate anatomical images and, with some techniques, functional information. One of the advantages of MRI over CT is that in MR studies no ionizing radiation is used, but its main advantage is its superior soft tissue contrast when compared with all other modalities. This chapter explains terminology; fundamental principles of magnetic resonance imaging; indications; safety; technique; contrast media; protocols; principles of interpretation; abnormalities, artefacts and pitfalls.

Objective—To determine whether clinical and clinicopathologic data could assist differentiation of congenital portosystemic shunts (CPSSs) from acquired portosystemic shunts (APSSs) in young dogs. Design—Retrospective case series. Animals—Dogs < 30 months of age with CPSSs (n = 62) or APSSs (31). Procedures—Medical records from 3 referral centers identified 31 dogs with APSSs and 62 dogs with CPSSs diagnosed from July 2003 to July 2008. Signalment, clinical signs, physical examination, and clinicopathological data were recorded, and statistical analyses were performed to determine differences between groups. Results—Univariable analysis showed APSS patients were older, heavier, and in poorer body condition, compared with CPSS patients. In CPSS patients, diarrhea was less prevalent, and neurologic signs were more prevalent. Ascites was more prevalent in APSS (Fisher exact test; OR, 50.2; 95% confidence interval [CI], 6.2 to 409.7), with no significant difference in albumin concentration between groups. The logistic regression model used to assess clinicopathological parameters showed lower Hct (OR, 1.42 × 10−12; 95% CI, 1.42 × 10−17 to 4.0 × 10−6), higher mean corpuscular volume (OR, 1.27; 95% CI, 1.08 to 1.50), and higher alanine aminotransferase concentrations (OR, 1.005; 95% CI, 1.001 to 1.009) were more likely in APSS patients. Conclusions and Clinical Relevance—Several clinicopathologic differences between dogs with congenital and acquired shunts were identified; however, assessed alone, these would be unlikely to enable differentiation between the 2 conditions. Awareness of the rarity of ascites in CPSS cases should prompt recognition of a likely diagnosis of APSS, allowing the veterinarian to target further diagnostics and counsel the owner appropriately.

Greyhound nonsuppurative meningoencephalitis is an idiopathic breed-associated fatal meningoencephalitis with lesions usually occurring within the rostral cerebrum. This disorder can only be confirmed by postmortem examination, with a diagnosis based upon the unique topography of inflammatory lesions. Our purpose was to describe the magnetic resonance (MR) imaging features of this disease. Four Greyhounds with confirmed Greyhound nonsuppurative meningoencephalitis were evaluated by MR imaging. Lesions predominantly affected the olfactory lobes and bulbs, frontal, and frontotemporal cortical gray matter, and caudate nuclei bilaterally. Fluid attenuation inversion recovery (FLAIR) and T2 weighted spin-echo (T2W) sequences were most useful to assess the nature, severity, extension, and topographic pattern of lesions. Lesions were predominantly T2-hyperintense and T1-isointense with minimal or absent contrast enhancement.

Ventriculo-peritoneal shunting is a surgical treatment for hydrocephalus. Complications of this procedure are not well described in dogs. The most common complication in humans is infection, which can be fatal if not diagnosed and treated quickly. We describe the magnetic resonance (MR) imaging characteristics of a shunt-associated cerebral infection in a dog. The MR features of the infection included hyperintensity of the lining of the ventricular system visible on a T2-weighted FLAIR sequence and marked linear contrast enhancement of the ependymal layer on T1-weighted sequences, similar to that described in people.

A 12-week-old male Golden Retriever was presented with signs of right-sided congestive heart failure and a grade V/VI left craniosternal systolic murmur. Echocardiography identified a double-chambered right ventricle and dilated coronary sinus (CS) running into an inter-atrial chamber. This was confirmed to be an imperforate cor triatriatum dexter (CTD) by selective angiographic studies. To the authors’ knowledge this is the first case reported of imperforate CTD successfully treated by membranostomy and balloon dilation. Cardiac MRI confirmed the echocardiographic and angiographic findings and provided a more precise understanding of the venous abnormalities.

History A 2-year-old, entire female, Somali cat weighing 3.8 kg was admitted for a conjunctival graft on the right eye, for treatment of an acute descemetocele. Medetomidine 4.2 μg kg −1 and methadone 0.2 mg kg −1 were administered by intramuscular injection as preanaesthetic medication. Anaesthesia was induced using diazepam 0.26 mg kg −1 and propofol 4 mg kg −1 administered by intravenous (IV) injection. Following endotracheal intubation, anaesthesia was maintained with isoflurane delivered in oxygen (1 L minute −1 ) and nitrous oxide (2 L minute −1 ) via a non-rebreathing system. Twenty minutes after induction of anaesthesia, one drop of a 10% phenylephrine hydrochloride solution was administered topically to the right eye. Physical examination After phenylephrine administration, a decrease in heart rate (from 95 to 80 beats minute −1 ) and an increase in arterial blood pressure occurred. The pulse then became difficult to palpate manually and multifocal ventricular premature contractions were observed on the electrocardiogram. Management Nitrous oxide was discontinued and the isoflurane vaporizer setting was decreased from 1.5% to 0.5%. Lidocaine 1 mg kg −1 IV was administered, this resulted in ventricular bigeminy. The quality of the femoral pulse improved and was regular in rhythm and character. Surgery was completed as fast as possible. The bigeminy progressively disappeared and before disconnecting the cat from the breathing system, there was a normal sinus rhythm with a heart rate of 85 beats minute −1 . Follow-up Echocardiography was performed during recovery and showed mitral and aortic valve insufficiency and dilation of the left ventricle, suggesting a reduction in systolic function. Echocardiography was repeated the following day and was normal. Conclusions In order to diminish the potential for cardiovascular sequelae associated with systemic absorption of ocular phenylephrine, less concentrated solutions, smaller drop size or different instillation techniques should be considered for topical use in small patients.

Sixteen dogs with acute-onset, non-progressive signs of brain dysfunction and magnetic resonance imaging (MRI) characteristics compatible with thalamic infarction are described. Topographically the MRI lesions could be grouped in three thalamic regions, namely, paramedian (8/16), extensive dorsal (5/16) and ventrolateral (3/16). Paramedian lesions resulted in signs typical of vestibular dysfunction. Extensive dorsal lesions were associated with vestibular ataxia, circling and contralateral menace response deficits. Ventrolateral lesions resulted in circling and contralateral proprioceptive deficits. In several dogs, regions other than the thalamus were also affected: four extended into the midbrain; six extended to the internal capsule, and two dogs had a second lesion in the cerebellum. Three clinical syndromes were identified in association with thalamic infarction. These signs varied somewhat, most likely because lesions were not confined to specific nuclear boundaries and involved different combinations of thalamic nuclei.

A 2-year-old, male Weimaraner presented with acute-onset nonaxial exophthalmos with dorsal deviation of the left globe. Periorbital swelling, pain and a profuse purulent ocular discharge were present on the left side. A draining sinus tract was present in the left ventral conjunctival fornix and another in the left pterygopalatine fossa. The right eye was normal on complete ophthalmic examination. Orbital ultrasonography revealed large, double, linear, parallel echogenic bands with shadowing present in the ventrolateral aspect of the left orbit suggestive of a foreign body. Deformation of the posterior segment was also present. Removal of the orbital foreign body was attempted under ultrasound guidance via the discharging sinuses in the ventral conjunctival fornix and the pterygopalatine fossa. Neither approach was successful; however, a small amount of organic material was retrieved confirming the diagnosis of orbital foreign body. Magnetic resonance imaging (MRI) revealed a linear foreign body of 8 x 1.5 x 0.8 cm extending from the orbit to the level of the oropharynx. A modified lateral orbitotomy with zygomatic arch resection on the left side allowed removal of the wooden foreign body.

In humans affected with inflammatory myopathies, regions of altered signal intensity are found on magnetic resonance (MR) images of affected muscles. Although electromyography (EMG) is more practical for muscle disease evaluation, and a muscle biopsy is the only manner in which a definitive diagnosis can be made, MR imaging has proven useful if a specific anatomic localization is difficult to achieve. Three dogs with focal inflammatory myopathy diagnosed with the assistance of MR imaging are discussed and the findings are compared with those found in humans. MR images of the affected muscles in each dog were characterized by diffuse and poorly marginated abnormal signal on T1- and T2-weighted images. Marked enhancement was noted in these muscles after contrast medium administration. An inflammatory myopathy was confirmed histologically in all three dogs. A good association existed between the MR images and muscle inflammation identified histopathologically. MR imaging may be a useful adjunctive procedure for canine inflammatory myopathies.

Intervertebral disk extrusion is rarely reported in the cat. In this case, the clinical, radiologic, and magnetic resonance imaging findings of an acute intramedullary intervertebral disk extrusion in a 5-year-old domestic shorthaired cat are described. Radiographically, there was mineralized disk material within the vertebral canal. On magnetic resonance images, the disk material was found to be within the spinal cord. A linear disk trail extending from the disk space into the spinal cord may be specific for intramedullary disk extrusion.

Medullobastoma is an uncommon caudal fossa tumor. The imaging features of medullobastoma in the dog are poorly described. In this report, the magnetic resonance (MR) appearance of a cerebellar medullobastoma in a dog is described. The MR features were similar to medulloblastomas in adult humans, with the tumor arising laterally and extending to the surface of the cerebellar hemisphere. Correct localization of medulloblastoma may be difficult and it should be considered as a differential for both extra- and intra-axial caudal fossa masses.

An 8-month-old German Shepherd dog was presented for investigation of pelvic limb gait abnormality. Neurolocalization indicated a T3-L3 spinal cord lesion. The myelographic appearance was of an intramedullary lesion at T9/10, but upon subsequent magnetic resonance imaging it was determined that the mass was extramedullary. A diagnosis of nephroblastoma was made on histological examination. The imaging features of this rare tumor and the differentiation of intradural-extramedullary and intramedullary masses are discussed.

Eosinophilic bronchopneumopathy is a disease characterized by the infiltration of the lung and bronchial mucosa by eosinophils. The aim of the present study was to describe the CT findings in a large series of dogs with confirmed diagnosis of eosinophilic bronchopneumopathy. Computed tomographic scans of 15 dogs with confirmed diagnosis of eosinophilic bronchopneumopathy were evaluated retrospectively by two boarded radiologists who reached a consensus. Abnormalities were identified in 14/15 (93%) dogs, including pulmonary parenchymal abnormalities in 14/15 (93%) dogs, bronchial wall thickening in 13 (87%) dogs, which was considered marked in eight (53%), plugging of the bronchial lumen by mucus/debris in 11 (73%) dogs, and bronchiectasis in nine (60%) dogs. Pulmonary nodules were identified in 5/15 (33%) dogs including one dog with a mass. All dogs with a nodular lung pattern had additional abnormalities. Lymphadenopathy was present in 10 dogs (67%). Lesions associated with eosinophilic bronchopneumopathy are variable and heterogeneous and encompass a wider variety of computed tomographic features than reported previously. Computed tomographic images were abnormal in the majority of affected dogs, hence CT is a useful modality to characterize the nature and distribution of thoracic lesions in dogs with eosinophilic bronchopneumopathy.

Septic pericarditis and myocardial abscess are rare conditions in dogs. They are usually caused by foreign bodies, penetrating wounds, systemic infections or extension of local infections such as endocarditis, pleuritis or pulmonary infections to the myocardial tissue. Here we report a septic pericardial effusion and myocardial abscess in a young English Springer spaniel presenting with a long history of pyrexia and lethargy. No cause could clearly be identified although a penetrating injury or dissolving foreign body was highly suspected. The patient was successfully treated with a surgical approach in combination with broad spectrum antibacterials resulting in resolution of clinical signs without recurrence of the infection.

Computed tomography (CT) is an established technique for detecting shoulder lesions in dogs, however the clinical significance of shoulder CT lesions often remains uncertain. The purposes of this retrospective study were to describe the prevalence of CT lesions in both shoulder joints for 89 dogs presenting with thoracic limb lameness and to compare CT lesions with clinical characteristics. For all included dogs, results of a full orthopedic examination, other diagnostic tests, and signalment data were available in medical records. Multilevel, multivariable logistic regression was used to test clinical significance of the most prevalent CT lesions and determine factors associated with their presence. Computed tomographic lesions were detected in one or both shoulder joints for 51/89 dogs (57.3%). Mineralization of one or more surrounding peri-articular soft-tissue structures was identified in 31.5% of dogs, with supraspinatus muscle/tendon mineralization being the most frequently identified (24.7%). The prevalence of humeral head osteochondrosis was 9 and 21.3% of dogs had shoulder osteoarthritis. Border collies (odds ratio [OR] 9.3; 95% CI 1.39-62.1, P = 0.02) and dogs with shoulder pain (OR 4.3; 95% CI 1.08-17.1, P = 0.04) had increased risk of osteochondrosis lesions. Border collies (OR 8.4; 95% CI 1.27-55.6; P = 0.03) and older animals (OR 1.04; 95% CI 1.02-1.1, P0.001) had increased risk of osteoarthritis lesions. Female entire dogs had an increased risk of supraspinatus mineralization lesions (OR 6.8; 95% CI 1.55-29.5, P = 0.01). Findings indicated that shoulder CT lesions are common in dogs with thoracic limb lameness, and that some CT lesions are not associated with shoulder pain.

Greyhound nonsuppurative meningoencephalitis is an idiopathic breed-associated fatal meningoencephalitis with lesions usually occurring within the rostral cerebrum. This disorder can only be confirmed by postmortem examination, with a diagnosis based upon the unique topography of inflammatory lesions. Our purpose was to describe the magnetic resonance (MR) imaging features of this disease. Four Greyhounds with confirmed Greyhound nonsuppurative meningoencephalitis were evaluated by MR imaging. Lesions predominantly affected the olfactory lobes and bulbs, frontal, and frontotemporal cortical gray matter, and caudate nuclei bilaterally. Fluid attenuation inversion recovery (FLAIR) and T2 weighted spin-echo (T2W) sequences were most useful to assess the nature, severity, extension, and topographic pattern of lesions. Lesions were predominantly T2-hyperintense and T1-isointense with minimal or absent contrast enhancement.

A 4-year-old neutered female terrier-cross was evaluated for an acute onset of paraplegia. Utilizing magnetic resonance (MR) imaging, the cause of the neurologic deficits was determined to be a lumbar intervertebral disc extrusion. The MR study additionally demonstrated parenchymal hyperintensity on T2-weighted images and similarly located diffuse hypointensity on gradient echo images, cranial and caudal to the compressive extradural lesion. Hemorrhagic myelomalacia was suspected based on these MR characteristics, which was subsequently confirmed surgically and histopathologically.

Ischemia and infarction of the spinal cord is a known cause of acute spinal injury in dogs. Currently, the diagnosis of spinal cord infarction in small animals is based on history, clinical signs, and the exclusion of other differentials with radiography and myelography. It is a diagnosis only confirmed through necropsy examination of the spinal cord. The aim of this paper is to describe the Magnetic resonance imaging (MRI) findings of the spinal cord of dogs with suspected spinal cord infarcts to utilize this technology for antemortem support of this diagnosis. This retrospective study evaluated the spinal MR examinations of 11 dogs with acute onset of asymmetric nonpainful myelopathies. All patients except one (imaged at 2 months) were imaged within 1 week of clinical signs and managed conservatively with minimal medical and no surgical intervention. They were followed clinically for a minimum of 4 months after discharge. MR findings in all dogs were characterized by focal, intramedullary, hyperintense lesions on T2-weighted images with variable contrast enhancement similar to what is reported in humans. Though it could not be used to diagnose spinal cord infarction definitively, MRI was useful in excluding extramedullary spinal lesions and supporting intramedullary infarction as a cause of the acute neurologic signs. Together with the history and clinical examination findings, MRI is supportive of a diagnosis of spinal cord infarction.