Case report: MRI and CT imaging features of a melanocytic tumour affecting a cervical vertebra in an adult dog, and review of differential diagnosis for T1W-hyperintense lesions.

A 7-year-old Lhasa Apso presented with a history of left thoracic limb lameness and neck pain. Magnetic resonance imaging revealed a well-defined, extradural lesion that was hyperintense on T1-weighted (T1W) images and isointense on T2-weighted (T2W) images and T2* images located at the left lamina of the C4 vertebra. Computed tomography showed an isoattenuating and contrast-enhancing mass centered on the left C4 vertebral lamina with associated osteolysis. The mass was surgically debulked, and histopathology revealed a malignant melanocytic tumour. The patient recovered completely and received radiotherapy and three doses of the melanoma vaccine as adjunctive treatment. Eighteen months following treatment, the patient presented with neck pain again, but further investigations were declined at this stage, and the patient was euthanised. To the author's knowledge, this is the first case report describing the imaging characteristics of a cervical extradural melanocytic tumour in a dog. This case illustrates the MRI and CT imaging features and treatment of a canine melanocytic tumour of the cervical vertebrae.

Paraneoplastic hypercalcemia in a canine patient with a mandibular salivary carcinoma.

OBJECTIVE: To describe a novel presentation of paraneoplastic hypercalcemia caused by a canine salivary carcinoma. ANIMAL: A 6-year-old intact male Husky with hypercalcemia and a spontaneous salivary carcinoma, stage III. CLINICAL PRESENTATION, PROGRESSION, AND PROCEDURES: The dog presented with polyuria, polydipsia, and hypercalcemia. Physical examination revealed a 37 X 43-mm firm mass in the ventrolateral aspect of the right-hand side of the neck, caudal to the temporomandibular joint. Incisional biopsy was suspicious of metastatic carcinoma to the mandibular lymph node. A full-body CT scan found a large, heterogenous, contrast-enhancing mass on the right ventrolateral neck that appeared to be originating from either the mandibular lymph node or right mandibular salivary gland. Parathyroid hormone-related protein was considered within normal reference intervals, and both parathyroid glands appeared ultrasonographically normal. TREATMENT AND OUTCOME: The patient was treated with a marginal surgical excision of the mass, without immediate complications. Histopathology confirmed the presence of a salivary carcinoma with narrow margins of excision and invasion of the mandibular lymph node. Twenty-four hours after surgery, ionized calcium returned to normal reference values and clinical signs completely resolved. CLINICAL RELEVANCE: Hypercalcemia is an urgent pathology with important systemic implications requiring prompt diagnosis and intervention. In this case report, we identify the first salivary carcinoma associated with a paraneoplastic hypercalcemia, including this pathology as a new differential diagnosis. The hypercalcemia resolved with marginal surgical excision, but interestingly the parathyroid hormone-related protein was not overexpressed, meaning that this neoplasia could mediate hypercalcemia by another pathophysiological mechanism.

Feline Emphysematous Gastritis in a Cat with Pancreatitis and Secondary Hepatic Lipidosis.

A 7 yr old female neutered domestic shorthair was presented with a 2 mo history of lethargy and hyporexia progressing to anorexia. Initial diagnostics indicated pancreatitis with secondary hepatic lipidosis. Supportive care, including the placement of an esophageal feeding tube, was initiated. The feeding tube was removed traumatically by the cat and thus replaced. The cat acutely deteriorated while hospitalized, developing marked hypersalivation and an obtunded mentation. Radiographs were taken to confirm placement of the feeding tube in case tube dislodgement was contributing to the hypersalivation; results confirmed appropriate positioning and gastric pneumatosis. Despite intensified medical management, the patient suffered cardiopulmonary arrest 7 days after hospital admission. Post-mortem examination confirmed necrotizing gastritis with emphysema alongside segmental mucosal necrosis in the jejunum, focal pancreatic necrosis, and diffuse hepatic lipidosis. Gas in the gastric wall is a rare finding in veterinary medicine and can arise due to gastric pneumatosis or emphysematous gastritis; there are scant reports of either in feline medicine. This report documents a case of emphysematous gastritis in a cat with concurrent pancreatitis and hepatic lipidosis. The cat developed emphysematous gastritis without undergoing gastrointestinal surgery which is currently the only reported feline predis-posing factor for development.

MRI features of canine hemangiosarcoma affecting the central nervous system.

Hemangiosarcoma is the most common metastatic tumor involving the brain in dogs but detailed published descriptions of the magnetic resonance imaging (MRI) features are lacking. The objective of this multi-center, retrospective case series study was to describe MRI characteristics of canine hemangiosarcoma affecting the central nervous system (CNS). Medical records of seven referral institutions were retrospectively reviewed. Dogs were included if they had a histopathologically confirmed diagnosis of hemangiosarcoma affecting the CNS and undergone an MRI of the brain and/or vertebral column. Lesions were independently evaluated by two observers. Twenty dogs met the inclusion criteria and one dog had both intracranial and intramedullary hemangiosarcoma. Consistent MRI features included heterogeneous (17/21) lesions in all sequences with mainly mixed signal intensity (12/21), presence of susceptibility artifact on T2*w (15/16), associated moderate to severe perilesional edema (21/21), and moderate to strong (20/21) heterogeneous (14/21) or ring-like (6/21) contrast enhancement. Intracranial hemangiosarcoma was frequently multiple and intra-axial, affecting consistently the telencephalon and no differences in MRI features were found between primary and metastatic hemangiosarcoma. This is the first MRI description of primary intracranial hemangiosarcoma and primary intracranial epithelioid hemangiosarcoma. Vertebral hemangiosarcomas were segmental poorly marginated polyostotic and highly aggressive lesions invading the thoracic vertebral canal and paraspinal tissues. Epidural hemangiosarcomas were single and well-marginated lesions in the thoracolumbar and/or lumbar region. Intramedullary hemangiosarcomas were cervical, metastatic in origin, and frequently (3/4) accompanied by intracranial lesions. These described MRI features will aid early identification of hemangiosarcoma guiding subsequent diagnostics and therapeutics.

Comparison of CT features of 79 cats with intranasal mass lesions.

OBJECTIVES: This retrospective multicentre study compared the CT characteristics of cats diagnosed with intranasal mass lesions to determine if defining imaging features exist between different tumour types and between neoplastic and non-neoplastic lesions. METHODS: The medical records of two institutions were reviewed for cats with CT findings consistent with an intranasal mass lesion with subsequent histopathological examination. For each CT scan the mass location, growth pattern, margin distinction, contrast enhancement pattern and presence of intralesional areas of mineralisation or necrosis were recorded. The presence of facial deformity, the location and type of bone changes, extranasal extension of the mass lesion and the regional lymph nodes size, contrast pattern and hilus visibility were also documented. RESULTS: Thirty-five cats with nasal lymphoma, 28 cats with non-lymphomatous nasal neoplasia (carcinoma or sarcoma) and 16 cats with inflammatory lesions met the inclusion criteria. Cats with non-lymphomatous nasal neoplasia were more likely to show unilateral nasal changes (odds ratio [OR] 3.9), areas of intralesional calcification (OR infinity) and extension of the mass lesion within the frontal sinus (OR 4.5), while cats suffering from nasal lymphoma were more likely to show a mixed (OR 4.5) and expansile growth pattern (OR 7.8), and a regional lymphadenomegaly (OR 2.4). The CT findings in cats diagnosed with inflammatory mass-like lesions were highly variable and overlapped with findings for nasal neoplasms but were significantly associated with the absence of bony changes to the nasal cavity boundaries (OR 10.2). CONCLUSIONS AND RELEVANCE: Findings from the current study support the ability of CT to aid in the discrimination of tumour type in cats presented with an intranasal mass lesion.

Evaluation of radiographs for the detection of sublumbar lymphadenopathy in dogs.

The purpose of this study was to evaluate radiographs for the detection of sublumbar lymph node (SLN) enlargement. Ultrasound was used to determine SLN size. Twenty-two dogs with anal gland adenocarcinoma or lymphoma were prospectively included, with 16/22 having SLN enlargement on ultrasound. Twenty-one dogs without enlargement were retrospectively included as controls. Three blinded observers evaluated 43 right lateral abdominal radiographs for the presence of SLN enlargement. Sensitivity and specificity of radiographs for the detection of SLN enlargement were 81%/70%, 94%/81%, and 75%/100% for a general practitioner, imaging resident, and radiologist, respectively. Ventral displacement of the colon, a soft tissue opacity in the caudal retroperitoneal space and loss of conspicuity of the ventral margin of the iliopsoas muscle were radiographic findings significantly associated with identification (P-values < 0.05). Markedly enlarged SLNs (> 21.5 mm) were consistently detected radiographically by observers with specialist imaging training. Key clinical message: Radiographic visualization should raise suspicion of neoplastic infiltration of SLN but lack of visualization does not exclude mild to moderate enlargement. Additional imaging such as ultrasound or computed tomography remains important to confirm or exclude sublumbar lymphadenopathy.

Évaluation de radiographies pour la détection de lymphadénopathie sub-lombaire chez des chiens. Le but de la présente étude était d'évaluer des radiographies pour détecter l'augmentation de taille des ganglions sub-lombaires (SLN). L'échographie fut utilisée pour déterminer la taille des SLN. Vingt-deux chiens avec un adénocarcinome des glandes anales ou un lymphome furent inclus prospectivement, avec 16/22 ayant des SLN augmentés lors de l'échographie. Vingt-et-un chiens sans augmentation de taille furent inclus rétrospectivement comme témoins. Trois observateurs ont évalué à l'aveugle 43 radiographies abdominales latérales droites pour la présence d'augmentation des SLN. La sensibilité et la spécificité des radiographies pour la détection d'augmentation des SLN étaient de 81 %/70 %, 94 %/81 % et 75 %/100 % pour un praticien généraliste, un résident en imagerie et un radiologiste, respectivement. Un déplacement ventral du côlon, une opacité des tissus mous dans l'espace rétropéritonéal caudal et une perte de visibilité de la bordure ventrale du muscle iliopsoas furent des trouvailles radiographiques associées significativement avec l'identification (P < 0,05). Des SLN avec une forte augmentation de taille (> 21,5 mm) étaient constamment détectés radiographiquement par des observateurs avec une formation spécialisée en imagerie.Message clinique clé:La visualisation radiographique devrait soulever des soupçons d'infiltration néoplasique des SNL mais le manque de visualisation n'exclu pas une augmentation de taille de légère à modérée. Des analyses en imagerie additionnelles, telles que l'échographie ou la tomodensitométrie, demeurent importantes pour confirmer ou exclure une lymphadénopathie sub-lombaire.(Traduit par Dr Serge Messier).

Effect of osteoarthritis on the repeatability of patella tendon angle measurement in dogs.

OBJECTIVE: To evaluate the influence of osteoarthritis on the measurement of patella tendon angle (PTA) and determine intraobserver and interobserver variability. STUDY DESIGN: Retrospective clinical study. SAMPLE POPULATION: Eighty-seven mediolateral radiographs that were obtained prior to tibial tuberosity advancement. METHODS: Radiographic osteoarthritis was scored by 2 observers using guidelines derived from the International Elbow Working Group Protocol. Patella tendon angle was measured by 3 observers on 3 occasions, with at least 7 days between measurements. The data were statistically analyzed via weighted κ and Kruskal-Wallis testing. RESULTS: A fair strength of agreement was found among observers scoring osteoarthritis, with the same grades in 48% of radiographs. The intraobserver average bias between PTA measurements 1 and 3 ranged from -0.38° to -0.94°. Interobserver bias in angle measurement ranged from -0.92° to -2.00°. Observer 1 had the narrowest range of PTA differences (12.1°), and observer 3 had the highest range of PTA differences (23.5°). Observer 2 had the lowest mean bias (-0.38°). The mean bias was lowest between observers 1 and 2 (-0.92°) and highest between observers 1 and 3 (-2.0°). The mean intraobserver standard deviation of the PTA measurement differences was 2.90°, and interobserver standard deviation of the PTA measurement differences was 2.26°. The degree of osteoarthritis did not influence PTA measurements or their variability. CONCLUSION: The current study did not find evidence of an influence of osteoarthritis on PTA or on the repeatability of measurements. CLINICAL SIGNIFICANCE: Our findings suggest that osteoarthritis should not affect the radiographic planning for tibial tuberosity advancement surgery. The high variances in PTA measurement in less experienced observers may influence the clinical outcome of surgery.

IMAGING DIAGNOSIS-MAGNETIC RESONANCE IMAGING OF DIFFUSE LEPTOMENINGEAL OLIGODENDROGLIOMATOSIS IN A DOG WITH "DURAL TAIL SIGN".

A case of diffuse leptomeningeal oligodendrogliomatosis affecting the brain and spinal cord of a dog is presented. A 7.5-year old, male neutered Staffordshire bull terrier presented for evaluation of a chronic history of tetraparesis and seizures, with a multifocal neuroanatomical localization was determined. Extra-axial intradural lesions with an atypical presentation of a dural tail sign were seen on MRI. Histologically, the lesions were consistent with leptomeningeal oligodendrogliomatosis. To the authors' knowledge, a dural tail sign has not previously been reported as an MRI characteristic of diffuse leptomeningeal oligodendrogliomatosis in dogs.

Ultrasonographic identification of the dorsal atlantoaxial ligament in dogs.

OBJECTIVE: To determine the ability to identify the dorsal atlantoaxial ligament during ultrasonographic examination of dogs. STUDY DESIGN: Canine cadaveric study. SAMPLE POPULATION: Canine cervical spines (n = 35). METHODS: Thirty-five canine cadavers with an estimated body weight of 6-35 kg were retrieved. Five cervical spines were dissected to assess the length and thickness of the dorsal atlantoaxial ligament and correlate ultrasound-guided injection of ink with anatomical dissection. Ultrasonographic evaluation of the dorsal atlantoaxial ligament was performed on 30 cadavers. The visibility of the dorsal atlantoaxial ligament in both the transverse and the sagittal planes was subjectively scored (0-3). RESULTS: The dorsal atlantoaxial ligament was detectable on ultrasonographic examination in all cadavers: 27/30 and 28/30 were graded as moderately visible (grade 2) or clearly visible (grade 3) in the sagittal and transverse view, respectively. Only 1/30 cadaver specimen of a large breed dog was graded as 1 (indistinct) in both the sagittal and transverse planes. None of the cadavers were graded as 0 (not visible) in any view. CONCLUSION: The dorsal atlantoaxial ligament can be identified in ultrasonographic examination of normal canine cadavers. Future studies on animals with clinical atlantoaxial instability/subluxation are needed to evaluate the role of this imaging technique in providing a safer diagnosis of this condition. CLINICAL RELEVANCE: Ultrasonographic examination of the dorsal atlantoaxial ligament could potentially provide a noninvasive and safe imaging technique that may contribute to the diagnosis of atlantoaxial instability/subluxation in dogs.

Further characterization of computed tomographic and clinical features for staging and prognosis of idiopathic pulmonary fibrosis in West Highland white terriers.

Idiopathic pulmonary fibrosis is an interstitial lung disease of unknown etiology resulting in progressive interstitial fibrosis, with a known predilection in West Highland white terriers. In humans, computed tomography (CT) is a standard method for providing diagnostic and prognostic information, and plays a major role in the idiopathic pulmonary fibrosis staging process. Objectives of this retrospective, analytical, cross-sectional study were to establish descriptive criteria for reporting CT findings and test correlations among CT, clinical findings and survival time in West Highland white terriers with idiopathic pulmonary fibrosis. Inclusion criteria for affected West Highland white terriers were a diagnosis of idiopathic pulmonary fibrosis and available CT, bronchoscopy, bronchoalveolar lavage, echocardiography, and routine blood analysis findings. Clinically normal West Highland white terriers were recruited for the control group. Survival times were recorded for affected dogs. The main CT lung pattern and clinical data were blindly and separately graded as mild, moderate, or severe. Twenty-one West Highland white terriers with idiopathic pulmonary fibrosis and 11 control West Highland white terriers were included. The severity of pulmonary CT findings was positively correlated with severity of clinical signs (ρ = 0.48, P = 0.029) and negatively associated with survival time after diagnosis (ρ = -0.56, P = 0.025). Affected dogs had higher lung attenuation (median: -563 Hounsfield Units (HU)) than control dogs (median: -761 HU), (P < 0.001). The most common CT characteristics were ground-glass pattern (16/21) considered as a mild degree of severity, and focal reticular and mosaic ground-glass patterns (10/21) considered as a moderate degree of severity. Findings supported the use of thoracic CT as a method for characterizing idiopathic pulmonary fibrosis in West Highland white terriers and providing prognostic information for owners.

IMAGING DIAGNOSIS-MAGNETIC RESONANCE IMAGING AND HISTOPATHOLOGICAL FEATURES OF A SKULL BASE CHORDOMA IN A CAT.

An 8-year-old domestic short-haired cat was presented with anorexia, lethargy, ataxia and one episode of consciousness loss. A midline vertically orientated, biconcave, extra-axial mass originating from the basioccipital bone was detected on magnetic resonance images of the head. The mass was T1W iso- to hypointense when compared with normal grey matter, T2W hyperintense with small areas of isointensity and heterogeneously enhanced with contrast. Multiple signal voids were observed on T2* images. Histopathological evaluation confirmed a chordoma. To the authors' knowledge this is the first report of the imaging characteristics of a chordoma affecting the skull base in a cat.

Ventral occipito-atlanto-axial fluid-filled lesion causing dynamic spinal cord compression in a cat.

Cystic lesions affecting the vertebral canal or spinal cord have rarely been reported in cats. A 3-year-old female neutered domestic longhair cat presented for evaluation of a 2-year-history of episodes of ataxia and paresis affecting all limbs. Neurological examination was consistent with a lesion in the C1-C5 spinal cord segments. Magnetic resonance imaging (MRI) showed a fluid-filled lesion at the occipito-atlanto-axial region causing dynamic spinal cord compression on flexion of the neck. The imaging characteristics were compatible with a juxta-articular cyst. To our knowledge, this is the first report of a fluid-filled lesion causing dynamic cervical spinal cord compression in a cat and highlights the importance of performing flexion-extension MRI views in diagnosing cases with dynamic spinal cord compression.

Epineurial repair of an iatrogenic facial nerve neurotmesis after total ear canal ablation and lateral bulla osteotomy in a dog with concurrent cranio-mandibular osteopathy.

A 7-year-old male entire West Highland white terrier was referred to the Small Animal Hospital at the University of Glasgow for bilateral, chronic, medically unresponsive otitis media and externa. A history of cranio-mandibular osteopathy was also reported. Bilateral total ear canal ablation and lateral bulla osteotomy was performed with the aid of a pneumatic burr. Extensive bone proliferation was present bilaterally originating from the caudal mandibular ramus and tympanic bulla which incorporated the horizontal canal on each side. The right facial nerve was identified leaving the stylomastoid foramen and running in a cranial direction through a 1.5 cm diameter cuff of bone surrounding the horizontal canal and external acoustic meatus. Despite careful dissection, a facial nerve neurotmesis ensued which required microsurgical epineurial repair. Neurologic examination performed 12 h post-operatively revealed abnormalities consistent with right facial nerve paralysis. At 3 months, the facial nerve function was found to have improved significantly and was assessed to be normal four months after surgery. To the authors' knowledge, this clinical communication described the first reported clinical case where unilateral facial nerve paralysis resulting from iatrogenic facial nerve neurotmesis was successfully treated by microsurgical epineurial repair.

Radiographic measurements of the trachea in domestic shorthair and Persian cats.

Tracheal diameter can be assessed from a thoracic radiograph, with assessment of tracheal diameter in dogs based on ratios between tracheal diameter and a skeletal measurement. Reference intervals are not, however, available for the cat. Tracheal narrowing may cause significant clinical problems, although tracheal hypoplasia in dogs may be clinically silent, and is rarely reported in cats (both mesati- and brachycephalic). The tracheal diameter and trachea:thoracic inlet and trachea:rib ratios were calculated for populations of domestic shorthair (DSH) (n = 68) and Persian (n = 40) cats. This gave reference intervals for radiographic tracheal measurements in these breeds. It is proposed that the tracheal diameter in a normal DSH cat should be 18% of the diameter of the thoracic inlet, and compared to 20% in Persian cats.

Imaging findings in 11 cats with feline dysautonomia.

Dysautonomia is caused by degeneration of the autonomic ganglia. Failure of the autonomic system affecting the gastrointestinal and urinary tracts can cause oesophageal distension and/or dysfunction, gastric and bowel distension and hypomotility, and urinary bladder distension. The aim of this retrospective study was to describe diagnostic imaging findings in cats with dysautonomia. Common findings were megaoesophagus and/or oesophageal dysfunction, gastric distension and signs of intestinal ileus. Associated aspiration pneumonia and megacolon appeared less commonly. Although diagnostic imaging findings are not specific for this disease, if findings in multiple systems are detected, along with consistent clinical signs and neurological deficits, dysautonomia should be considered among the differential diagnosis.

Computed tomographic features of incomplete ossification of the canine humeral condyle.

OBJECTIVES: To describe computed tomographic (CT) features of canine elbows with incomplete ossification of the humeral condyle (IOHC) and investigate co-existing incongruence in the elbow joint. STUDY DESIGN: Case control study. ANIMALS: Dogs with IOHC (n=20; 38 elbows) and 25 normal elbows. METHODS: Elbows with IOHC and normal elbows were assessed by CT. Standardized dorsal and sagittal reconstructions were created at 3 levels using image analysis software to obtain single measurements of the humero-radial and humero-ulnar joint spaces. On dorsal plane reconstructions, joint space measurements were obtained at the center point of the humero-radial and humero-ulnar articulations. Joint incongruity was defined as the difference between the humero-radial and the humero-ulnar joint spaces. RESULTS: Nineteen dogs (95%), all Spaniel breeds, had either bilateral IOHC demonstrable as a saw-toothed intercondylar complete or incomplete hypoattenuating defect with hyperattenuating margins, or IOHC with contralateral humeral condylar fracture (HCF). Joint incongruity values for IOHC were compared with those of normal elbows. Significant differences were noted at the levels of the medial coronoid apex (P<.0001) and base (P<.004) indicative of humero-ulnar incongruence. Evidence of medial coronoid disease in 10 elbows (26%) and degenerative joint disease in 30 elbows (79%) was also found. CONCLUSIONS: Presence of elbow incongruence may be an underlying factor in failure of ossification centers to fuse leading to IOHC. CLINICAL RELEVANCE: IOHC is clearly defined by CT, and it should be considered in larger Spaniel breeds, with a chronic forelimb lameness or HCF.

Assessment of low-cost teleradiology for grading elbow dysplasia.

Teleradiology involves the creation of a radiographic image that is then transmitted electronically. It has been shown that low-cost teleradiology has a high level of agreement when comparing the original radiograph to the digital image. However, there has been little investigation of the effect of digitization on the score allocated by a grading scheme. Radiographs of 60 canine elbows were selected, each in three projections (mediolateral flexed, mediolateral neutral, craniocaudal). Each radiograph was photographed at 3 megapixel (3 M) and 6 megapixel (6 M) resolution using a digital camera. The images were placed in groups (radiographs, 3 M and 6 M) and randomized. Each elbow was independently graded by a radiologist and an orthopedic surgeon using the BVA elbow scoring scheme, with the different image sets interpreted separately. Intra and interobserver agreement was compared using a kappa analysis. The radiologist had substantial intraobserver agreement for repeated grading of radiographs, and moderate agreement for the other intraobserver tests (3 M vs. radiographs, 6 M vs. radiographs, 3 vs. 6 M). The surgeon had moderate to substantial agreement for the intraobserver tests. There was reduced interobserver agreement for all image groups. These results suggest that low-cost teleradiology may only allow moderate accuracy when used for grading schemes, and this may affect its use for breed scoring schemes. However, there appears to be an inherent subjectivity present in the elbow-grading scheme, seen in both intra and interobserver analysis. Therefore, further study of teleradiology using a different scoring model (e.g., hip dysplasia) may be indicated.