Gawain Hammond

Radiographic anatomy of the articular process joints of the caudal cervical vertebrae in the horse on lateral and oblique projections

REASONS FOR PERFORMING STUDYnPlain radiography is the standard imaging technique for investigation of diseases associated with the articular process joints (APJ) of the caudal neck; however, the radiographic anatomy of these structures on both lateral and oblique radiographic projections has not previously been described in detail.nnnOBJECTIVESnTo determine the optimal technique for obtaining oblique radiographs of the APJ of the caudal cervical vertebrae (C4-5, C5-6 and C6-7) and to provide a detailed description of their normal radiographic appearance, on both lateral and oblique radiographic projections.nnnMETHODSnRadiopaque markers were used to highlight the contours of the APJ on both lateral and oblique radiographs. A novel cineradiographic technique was employed to determine the optimal oblique projection to permit both left and right APJ to be assessed on the same radiograph. Lateral and oblique radiographs of the caudal neck were obtained in 6 live horses under standing sedation to assess the feasibility of the technique.nnnRESULTSnThe radiopaque markers facilitated identification of the APJ by clearly outlining the margins of the cranial and caudal articular processes on lateral and oblique radiographs. The optimal range of angles for obtaining oblique radiographs was 50-55 degrees for C4-5, 45-55 degrees for C5-6 and 45-5 degrees for C6-7. Obtaining oblique radiographs within the specified range of angles resulted in a consistent radiographic image of the APJ in the caudal cervical region in the live individual.nnnCONCLUSIONS AND POTENTIAL RELEVANCEnThe description of the normal radiographic anatomy of the cervical APJ of the caudal neck region in horses provides a valuable reference for the interpretation of cervical radiographs. Using the standardised technique to obtain oblique radiographs of the equine cervical vertebrae may provide additional diagnostic information about the APJ.

Computed Tomographic Features of Incomplete Ossification of the Canine Humeral Condyle

OBJECTIVESnTo 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.nnnSTUDY DESIGNnCase control study.nnnANIMALSnDogs with IOHC (n=20; 38 elbows) and 25 normal elbows.nnnMETHODSnElbows 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.nnnRESULTSnNineteen 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.nnnCONCLUSIONSnPresence of elbow incongruence may be an underlying factor in failure of ossification centers to fuse leading to IOHC.nnnCLINICAL RELEVANCEnIOHC is clearly defined by CT, and it should be considered in larger Spaniel breeds, with a chronic forelimb lameness or HCF.

Radiographic analysis of trochlear notch sclerosis in the diagnosis of osteoarthritis secondary to medial coronoid disease.

Trochlear notch sclerosis (TNS) as assessed by radiography has been shown to be increased in elbow dysplasia (ED) associated medial coronoid process disease (MCD). The aims of this study were to investigate whether two defined radiographic tests evaluating TNS would increase the sensitivity of detecting osteoarthritis secondary to MCD, and to assess whether there was a correlation between increasing TNS with severity of MCD. Sixty-one dogs with MCD (121 elbows) were selected from the imaging database. The controls were nine cadavers (18 disease-free elbows). Standard International Elbow Working Group radiographs and CT scans were taken of each elbow. Plain radiographs were analysed using various assessments: osteophyte grade (0-3), coronoid grade (0-3), TNS descriptive grade (0-3) and TNS ratio. The TNS ratio was calculated from the depth of ulnar sclerosis at the level of the disto-cranial margin of the humeral condyles divided by the cranio-caudal ulna depth. The TNS descriptive assessment and ratio both increased the overall sensitivity of diagnosing osteoarthritis secondary to MCD above the other radiographic tests. The sensitivity of the TNS ratio at <0.3 mm was 91%-96% and the TNS descriptive assessment was 77%-96%. Radiographic TNS significantly increased with increasing severity of coronoid disease grade as evaluated by CT p < 0.01. The finding that TNS increases the sensitivity of diagnosing osteoarthritis secondary to MCD is valuable to those that have neither a CT scanner nor arthroscopy readily available. The assessments described in this study are easy to apply and do not require any sophisticated technology in order to detect sclerosis.

Effect of delayed acquisition times on gadolinium-enhanced magnetic resonance imaging of the presumably normal canine brain.

A delay in imaging following intravenous contrast medium administration has been recommended to reduce misdiagnoses. However, the normal variation of contrast enhancement in dogs following a delay has not been characterized. Contrast-enhanced MR imaging of 22 dogs was assessed, in terms of identification of normal anatomic structures, to investigate the variation associated with 10-min delay between contrast medium administration and imaging. All dogs had a normal brain MR imaging study and unremarkable cerebrospinal fluid. Specific regions of interest were assessed both objectively, using computer software, and subjectively using three observers. Mean contrast enhancement > 10% was seen in the pituitary gland, choroid plexus, meninges, temporal muscle, trigeminal nerve, and the trigeminal nerve root. Structures with an active blood-brain barrier had minimal contrast enhancement (< 6%). Enhancing structures had significantly more contrast enhancement at t = 1 min vs. t = 10 min, except in temporal muscle, the trigeminal nerve and the trigeminal nerve root. Interobserver agreement was moderate to good in favor of the initial postcontrast T1-weighted (T1w) sequence. The observers found either no difference or poor agreement in identification of the nonvascular structures. Intraobserver agreement was very good with all vascular structures and most nonvascular structures. A degree of meningeal enhancement was a consistent finding. The initial acquisition had higher enhancement characteristics and observer agreement for some structures; however, contrast-to-noise was comparable in the delayed phase or not significantly different. We provide baseline references and suggest that the initial T1w postcontrast sequence is preferable but not essential should a delayed postcontrast T1w sequence be performed.

Effect of delayed acquisition times on Gadolinium-enhanced MRI of the presumably normal canine brain

A delay in imaging following intravenous contrast medium administration has been recommended to reduce misdiagnoses. However, the normal variation of contrast enhancement in dogs following a delay has not been characterized. Contrast-enhanced MR imaging of 22 dogs was assessed, in terms of identification of normal anatomic structures, to investigate the variation associated with 10-min delay between contrast medium administration and imaging. All dogs had a normal brain MR imaging study and unremarkable cerebrospinal fluid. Specific regions of interest were assessed both objectively, using computer software, and subjectively using three observers. Mean contrast enhancement > 10% was seen in the pituitary gland, choroid plexus, meninges, temporal muscle, trigeminal nerve, and the trigeminal nerve root. Structures with an active blood-brain barrier had minimal contrast enhancement (< 6%). Enhancing structures had significantly more contrast enhancement at t = 1 min vs. t = 10 min, except in temporal muscle, the trigeminal nerve and the trigeminal nerve root. Interobserver agreement was moderate to good in favor of the initial postcontrast T1-weighted (T1w) sequence. The observers found either no difference or poor agreement in identification of the nonvascular structures. Intraobserver agreement was very good with all vascular structures and most nonvascular structures. A degree of meningeal enhancement was a consistent finding. The initial acquisition had higher enhancement characteristics and observer agreement for some structures; however, contrast-to-noise was comparable in the delayed phase or not significantly different. We provide baseline references and suggest that the initial T1w postcontrast sequence is preferable but not essential should a delayed postcontrast T1w sequence be performed.

Budd-Chiari-like syndrome caused by a congenital hiatal hernia in a shar-pei dog

CONGENITAL diaphragmatic hernias have been well documented in shar-pei dogs (Callan and others 1993). The presenting signs are usually regurgitation, vomiting and hypersalivation. Ascites has not been reported in congenital or acquired diaphragmatic hernias. This short communication describes a congenital hiatal hernia in a shar-pei dog that presented with ascites caused by a mechanical obstruction of the caudal vena cava (Budd–Chiari-like syndrome [BCLS]) (Van der Linde-Sipman and Stokhof 1974). A six-month-old male shar-pei dog was referred with a two-week history of regurgitation, abdominal enlargement and lethargy. There was no history of trauma. Physical examination revealed marked fluid distension of the abdomen, pitting oedema of the pelvic limbs (Fig 1), enlarged prescapular lymph nodes and a slight pyrexia (39·0°C). The initial diagnostic evaluation included serum biochemistry, haematology, urinalysis and analysis of abdominal fluid following paracentesis. Serum biochemistry demonstrated panhypoproteinaemia (albumin 20 g/l, reference range 29 to 36 g/l, globulin 19 g/l, reference range 28 to 42 g/l) and hypocalcaemia that was probably due to the hypoalbuminaemia. Mild hyperglycaemia and leucocytosis (monocytosis and neutrophilia), which were attributed to stress, were also identified. The urinalysis was unremarkable. The abdominal fluid was found to have a protein content of 28 g/l and a cell count of 0·375 x 109/l consisting of non-degenerate neutrophils, occasional eosinophils and a few macrophages. The enlarged lymph nodes were attributed to vascular congestion and were not investigated. A radiograph of the thorax demonstrated a large, soft tissue opacity containing some gas shadows in the caudo dorsal right thorax. An area of alveolar infiltrate partially obscured the cardiac silhouette. Loss of abdominal serosal detail secondary to a peritoneal effusion was evident (Fig 2). Abdominal ultrasonography confirmed the presence of moderately echogenic free fluid within the abdomen. The diaphragm appeared indistinct at the mid-ventral level. One liver lobe was identiVeterinary Record (2006) 159, 322-323

Further characterisation of the clinical features of chronic pulmonary disease in West Highland white terriers

A CHRONIC respiratory illness, typified by inspiratory crackles and an increased interstitial pattern on thoracic radiography, has been recognised to be particularly prevalent in West Highland white terriers (WHWTs) (Corcoran and others 1999a, b, Lobetti and others 2001, Webb and Armstrong 2002). It has been suggested that this condition may be analogous to idiopathic pulmonary fibrosis (IPF) in human beings, but there is currently no pathological proof to support this assertion. Nevertheless, this clinical presentation is commonly recognised in veterinary practice and the clinical features of the disease have been previously reported, but only in retrospective studies (Corcoran and others 1999a, b, Lobetti and others 2001, Webb and Armstrong 2002). The purpose of the present study was to use a prospective cross-sectional approach to better define and improve the clinical description of this group of WHWTs. For the purpose of this report the term chronic pulmonary disease (CPD) will be used.nnCases of suspected CPD were recruited at the universities of Glasgow, Edinburgh and Pennsylvania veterinary schools over a three-year period. For inclusion in the study, dogs had to have clinical evidence of chronic progressive respiratory disease, readily detectable crackles on thoracic auscultation and no evidence of significant cardiac disease. The minimum information required included clinical history, physical examination, haematology and biochemistry profiles, and thoracic radiography, high-resolution CT (HRCT), bronchoscopy and bronchoalveolar lavage with cytological analysis, under general anaesthesia. Bronchoscopic evaluation was predominantly used to assess for evidence of chronic bronchitis and dynamic airway collapse (Fig 1).nnnnFig 1 nBronchoscopic images at the level of the carina, illustrating differences in mucosal appearance between (a) a dog with interstitial disease (as determined by radiography and …

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.

Central diabetes insipidus associated with primary focal B cell lymphoma in a dog

CENTRAL diabetes insipidus is an uncommon condition characterised by polyuria due to a deficiency in the secretion of antidiuretic hormone from the posterior pituitary gland. The causes of central diabetes insipidus in dogs include intracranial tumours, such as craniopharyngioma, meningioma,

COMPUTED TOMOGRAPHIC FEATURES OF BASIHYOID ECTOPIC THYROID CARCINOMA IN DOGS

Eight dogs with a firm, nonpainful swelling in the ventral laryngeal region and with a final diagnosis of ectopic thyroid carcinoma were investigated by Computed Tomography (CT) at six different institutions. Computed Tomography findings were reviewed, focusing on lesion volume, shape, margins, relationship with surrounding structures and adjacent vessels, attenuation characteristics, and presence of metastases. Ectopic thyroid carcinomas were seen as oval-to-bilobed masses centered on the basihyoid bone with associated bone lysis, highly vascularized capsules with central poorly contrast enhancing areas. In all cases there was laryngeal wall infiltration, in two dogs invasion of the laryngeal lumen and in one case invasion of the ventral muscular and subcutaneous plane. Metastases were found in retropharyngeal lymph nodes (three cases) and in the lung (two cases). Ectopic thyroid carcinoma should be considered in the differential diagnosis when a mass in the basihyoid region is present. Described CT features may be typical for ectopic thyroid neoplasia and could be used to help decide the therapeutic plan.