Investigation of scan delays for CT evaluation of inner wall layering and peak enhancement of the canine stomach and small intestine using a 20 second fixed-injection-duration and bolus tracking technique.

Many gastrointestinal diseases affect the mucosal layer, suggesting that on computed tomography (CT) examination, detection of consistent inner wall layering of the gastrointestinal tract may aid in detection of disease. Changes in wall enhancement can also characterise specific diseases and provide prognostic information. The objectives of this mixed retrospective and prospective analytical study were therefore to identify the scan delays for peak detection of canine stomach and small intestinal inner wall layering and enhancement when using a 20 s fixed-injection-duration and bolus tracking technique. For each patient, 700 mg I/kg iohexol was administered intravenously. Bolus tracking was used to determine aortic arrival. Diagnostic scans were performed after a post-aortic arrival scan delay. Postcontrast CT series were grouped according to post-aortic arrival scan delay: 5 s (n = 17), 10 s (n = 18), 15 s (n = 23), 20 s (n = 10), 25 s (n = 6), 30 s (n = 14), 35 s (n = 17), 40 s (n = 24), and 180 s (n = 60). The stomach and small intestine were assessed for the presence of a contrast-enhancing inner wall layer and wall enhancement. Statistical modeling showed that the scan delays for peak inner wall layering and enhancement were 10 and 15 s for the small intestine, respectively, and 40 s for the stomach. For the injection protocol used in this study, assessment of the canine gastrointestinal tract may use scan delays of 10-15 s and 40 s.

Recommendations for standardized plane definition in canine cardiac MRI.

With the growing interest in cardiac magnetic resonance imaging (cMRI), veterinary radiologists will increasingly be asked to use this modality to answer complex cardiological questions. Plane alignment is crucial for reproducible assessment of the heart. Anesthesia time is a limiting factor in cMRI. Aims of this prospective experimental study were to introduce a flow chart for standardized cMRI-examination in dogs, to test it for reproducibility using a cardiac CT simulation and to estimate time requirements needed to complete the examination accurately. Six operators (3 radiologists, 1 cardiologist, 1 imaging-resident, 1 technician) simulated a cMRI examination on CT-scans of 6 healthy Beagle dogs twice within two to four weeks. Assessment included qualitative and quantitative scoring of plane quality and time requirements. The quality of planes was high for the left and moderate for the right side of the heart. The intraclass correlation coefficient (ICC) of linear measurements of structures on the left was good to excellent (ICC-range: 0.789-0.948) but dropped to moderate to poor levels for the right side (ICC-range: 0.429-0.738). The median time required to complete a full examination was 30 (range: 13-103) min in the first and 24 (range: 15-62) min in the second evaluation. It differed significantly between operators and was consistently shorter for the left than for the right side. In conclusion, a new standardized scheme for cMRI can be quickly adopted by radiologists with some expertise in cross sectional imaging. Qualitative and quantitative results were highly reproducible for the left but less for the right side.

Computer tomographic comparison of cranial spread of contrast in lumbosacral and sacrococcygeal epidural injections in dog cadavers.

OBJECTIVE: To compare the cranial spread of epidural injectates between lumbosacral (LS) and sacrococcygeal (SCo) approaches in order to guide volume selection for SCo epidural anaesthesia in the dog. STUDY DESIGN: Prospective, randomized cadaveric experimental study. ANIMAL: A group of 13 adult greyhound cadavers. METHODS: The greyhound cadavers were randomly allocated to receive an epidural injection of diluted contrast via the LS or SCo approach. Incremental volumes (0.1, 0.2, 0.4 and 0.6 mL kg-1) were injected consecutively, and a computed tomography (CT) scan was completed following every volume increment. Cranial spread of contrast was recorded by counting the number of vertebrae cranial to the LS space that the injectate had reached, expressed as a vertebral value (n). This vertebral value was measured taking into consideration the percentage of the cord surrounded by contrast (vertebral canal coverage, %). RESULTS: The cranial spread of contrast was similar at 0.1 mL kg-1 [1 (0-3) versus 2 (1-3) n], 0.2 mL kg-1 [3 (0-10) versus 3 (1-5) n], 0.4 mL kg-1 [12 (9-18) versus 11 (3-19) n] and 0.6 mL kg-1 [18 (12-20) versus 15 (10-23) n] for the LS and SCo injections, respectively (p = 0.945). There was a significant interaction between the volume injected and vertebral canal coverage (p < 0.001). CONCLUSIONS AND CLINICAL RELEVANCE: The cranial spread of contrast was similar, independent of whether the epidural injection was performed in the LS or SCo intervertebral space. Current volume guidelines used for the LS approach may produce similar distribution patterns when the SCo approach is used. Further studies are required in order to evaluate the in vivo effectiveness and the adequacy in differently sized dogs of the results found herein.

Cryptococcosis in the koala (Phascolarctos cinereus): pathogenesis and treatment in the context of two atypical cases.

Disseminated cryptococcosis caused by Cryptococcus gattii (molecular type VGI) was diagnosed in an adult free-ranging female koala (Phascolarctos cinereus). Subclinical cryptococcosis was later diagnosed in this koala's joey. In the adult koala, a pathological fracture of the tibia was associated with the bone lysis of marked focal cryptococcal osteomyelitis. Limb-sparing orthopedic intervention, in the setting of disseminated cryptococcosis, was judged to have a poor prognosis, and the adult koala was euthanized. The joey was removed and hand-reared. Serological testing revealed persistent and increasing cryptococcal capsular antigenemia in the absence of clinical signs of disease and it was subsequently treated with oral fluconazole for approximately 16 months, rehabilitated and released into the wild. It was sighted 3 months post-release in a good state of health and again at 18 months post-release but was not recaptured on either occasion. This is the first published report of cryptococcal appendicular osteomyelitis in a koala. It is also the first report of concurrent disease in a dependent juvenile and the successful treatment of subclinical cryptococcosis to full resolution of the cryptococcal antigenemia in a free-ranging koala. This paper provides a discussion of cryptococcal osteomyelitis in animals, host-pathogen-environment interactions and treatment and monitoring protocols for cryptococcosis in koalas. Published reports describing the treatment of cryptococcosis in koalas are also collated and summarised.

Vascular conspicuity differs among injection protocols and scanner types for canine multiphasic abdominal computed tomographic angiography.

Multiphasic multidetector computed tomographic angiography is a standard diagnostic test for canine abdominal vascular disorders. Three imaging protocols have been previously described. The test-bolus protocol allows precise timing but can be time consuming to perform. Bolus-tracking software is fast and easy to use but can be problematic for exact timing of vascular phases. A recently described fixed-injection-duration protocol is not influenced by body weight and provides a wider temporal window for arterial acquisitions. Objectives of this retrospective and prospective, multicentric, method comparison study were to determine which of the three multidetector computed tomographic angiography protocols allows best vascular conspicuity of the canine abdomen and to assess the influence of different multidetector computed tomography (CT) scanners on study quality. Triple-phase multidetector computed tomographic angiography canine abdominal studies from 30 dogs were retrospectively retrieved from three different institutions. Each institution performed one of the three computed tomographic angiography protocols (4-row and 16-row multidetector CT). Prospectively, the three protocols were also acquired with similar conditions on a 64-row MDCT in 21 dogs. Main abdominal vessels were scored by blinded readers for each phase. The fixed-injection-duration protocol had the best combined arterial and portal vascular conspicuity on scanners of limited speed, while the test-bolus protocol provided the best overall vascular conspicuity on 64-row multidetector CT scanner. The quality of arterial studies performed on 64-row MDCT scanner was improved compared to the ones performed on four- to 16-row multidetector CT scanners. Findings supported the fixed-injection-duration protocol as the best compromise between an ideal portal vascular enhancement and an easily reproducible protocol on scanners with low and high number of detector rows.

Effect of proximal translation of the osteotomized tibial tuberosity during tibial tuberosity advancement on patellar position and patellar ligament angle.

BACKGROUND: Cranial cruciate ligament insufficiency is a common orthopaedic problem in canine patients. This cadaveric and radiographic study was performed with the aim of determining the effect of proximal translation of the tibial tuberosity during tibial tuberosity advancement (TTA) on patellar position (PP) and patellar ligament angle (PLA). RESULTS: Disarticulated left hind limb specimens harvested from medium to large breed canine cadavers (n = 6) were used for this study. Limbs were mounted to Plexiglass sheets with the stifle joint fixed in 135° of extension. The quadriceps mechanism was mimicked using an elastic band. Medio-lateral radiographs were obtained pre-osteotomy, after performing TTA without proximal translation of the tibial tuberosity, and after proximal translation of the tibial tuberosity by 3mm and 6mm. Radiographs were blinded to the observer for distance of tibial tuberosity proximalization following radiograph acquisition. Three independent observers recorded PP and PLA (tibial plateau method and common tangent method). Comparisons were made between the stages of proximalization using repeated measures ANOVA. Patellar position was found to be significantly more distal than pre-osteotomy, if the tibial tuberosity was not translated proximally (P = 0.001) and if it was translated proximally by 3mm (P = 0.005). The difference between pre-osteotomy PP and 6mm proximalization was not significant. The PLA was significantly larger if the tibial tuberosity was not translated proximally compared to tibial tuberosity proximalization of 6mm using the tibial plateau and the common tangent methods (P = 0.006 and P = 0.015 respectively). CONCLUSIONS: Proximalizing the tibial tuberosity during TTA helps in maintaining vertical position of the patella in the patellar groove. Proximalization of the tibial tuberosity reduces PLA when compared to TTA without tibial tuberosity proximalization.

Influence of Scan Resolution, Thresholding, and Reconstruction Algorithm on Computed Tomography-Based Kinematic Measurements.

Radiographic data, including computed tomography (CT) and planar X-ray, is increasingly used for human and animal kinematic studies. There is a tendency toward using as high-resolution imaging as possible. Higher resolution imaging is one factor (in conjunction with the reconstruction algorithm), which may increase the precision of reconstructed three-dimensional (3D) surface models in representing true bone shape. However, to date no study has tested the effects of scan resolution, threshold, and 3D model reconstruction algorithm on the accuracy of bone kinematic results. The present study uses a novel method to do this where canine tarsal bones were positioned on a radiolucent Lego™ board and scanned before and after undergoing known translations and/or rotations. The digital imaging and communications in medicine (DICOM) images were acquired using two different CT scanning resolutions and processed using three different segmentation threshold levels and three different reconstruction algorithms. Using one bone as the reference bone, an iterative closest point (ICP) algorithm was used to register bones to a global co-ordinate system and allow measurement of other bone kinematics in terms of translations and rotations in and around the x-, y-, and z-axes. The measured kinematics were compared to the "known" kinematics, which were obtained from the Lego™ board's manufacturing standards and tolerances, to give accuracy error metrics for all bones. The results showed error in accuracy of measured kinematics was at subvoxel levels (less than 0.5 mm). Despite altering the volume and surface area of the 3D bone models, variation in resolution, segmentation threshold and reconstruction algorithm had no significant influence upon the accuracy of the calculated tarsal bone kinematics.

EFFECTS OF TWO CONTRAST INJECTION PROTOCOLS ON FELINE AORTIC AND HEPATIC ENHANCEMENT USING DYNAMIC COMPUTED TOMOGRAPHY.

This prospective study compared aortic and hepatic enhancement achieved using a contrast injection protocol with a fixed rate of 5 ml/s vs. that achieved using a protocol with fixed injection duration of 20 s in eight cats. Cats were assigned into two groups (Group 1, rate 5 ml/s; Group 2, duration 20 s). The dose of contrast was the same in both groups (740 mgI/kg). Regions of interest (ROI) were drawn in the aorta and liver for transverse scans acquired at the hepatic hilus. Time to peak aortic enhancement occurred significantly earlier in Group 1 (M = 11s, SD = 1.63) than in Group 2 (M = 25.5 s, SD = 2.51). Peak aortic enhancement was significantly higher in Group 1 (M = 1906.51 HU, SD = 368.64) than in Group 2 (M = 745.08 HU, SD = 201.84). Duration of aortic enhancement equal to or above 300 HU was statistically longer in Group 2 (M = 24.5 s, SD = 8.39) than in Group 1 (M = 10 s, SD = 1.63). There were no significant differences in time to peak liver enhancement, peak liver enhancement, or duration of hepatic arterial phase between groups. Findings supported the hypothesis that longer injection duration results in a broader bolus geometry with a longer time to peak and a lower peak aortic enhancement in cat. This strong influence of injection duration on timing of aortic enhancement may help future users optimize protocols for CT angiography of the aorta and multiphasic evaluation of the liver, pancreas, and small intestine.

Effects of stifle flexion angle and scan plane on visibility of the normal canine cranial cruciate ligament using low-field magnetic resonance imaging.

Low-field magnetic resonance imaging (MRI) is commonly used to evaluate dogs with suspected cranial cruciate ligament injury; however, effects of stifle positioning and scan plane on visualization of the ligament are incompletely understood. Six stifle joints (one pilot, five test) were collected from dogs that were scheduled for euthanasia due to reasons unrelated to the stifle joint. Each stifle joint was scanned in three angles of flexion (90°, 135°, 145°) and eight scan planes (three dorsal, three axial, two sagittal), using the same low-field MRI scanner and T2-weighted fast spin echo scan protocol. Two experienced observers who were unaware of scan technique independently scored visualization of the cranial cruciate ligament in each scan using a scale of 0-3. Visualization score rank sums were higher when the stifle was flexed at 90° compared to 145°, regardless of the scan plane. Visualization scores for the cranial cruciate ligament in the dorsal (H (2) = 19.620, P = 0.000), axial (H (2) = 14.633, P = 0.001), and sagittal (H (2) = 8.143, P = 0.017) planes were significantly affected by the angle of stifle flexion. Post hoc analysis showed that the ligament was best visualized at 90° compared to 145° in the dorsal (Z = -3.906, P = 0.000), axial (Z = -3.398, P = 0.001), and sagittal (Z = -2.530, P = 0.011) planes. Findings supported the use of a 90° flexed stifle position for maximizing visualization of the cranial cruciate ligament using low-field MRI in dogs.

Bone augmentation for cancellous bone- development of a new animal model.

BACKGROUND: Reproducible and suitable animal models are required for in vivo experiments to investigate new biodegradable and osteoinductive biomaterials for augmentation of bones at risk for osteoporotic fractures. Sheep have especially been used as a model for the human spine due to their size and similar bone metabolism. However, although sheep and human vertebral bodies have similar biomechanical characteristics, the shape of the vertebral bodies, the size of the transverse processes, and the different orientation of the facet joints of sheep are quite different from those of humans making the surgical approach complicated and unpredictable. Therefore, an adequate and safe animal model for bone augmentation was developed using a standardized femoral and tibia augmentation site in sheep. METHODS: The cancellous bone of the distal femur and proximal tibia were chosen as injection sites with the surgical approach via the medial aspects of the femoral condyle and proximal tibia metaphysis (n = 4 injection sites). For reproducible drilling and injection in a given direction and length, a custom-made c-shaped aiming device was designed. Exact positioning of the aiming device and needle positioning within the intertrabecular space of the intact bone could be validated in a predictable and standardized fashion using fluoroscopy. After sacrifice, bone cylinders (Ø 32 mm) were harvested throughout the tibia and femur by means of a diamond-coated core drill, which was especially developed to harvest the injected bone area exactly. Thereafter, the extracted bone cylinders were processed as non-decalcified specimens for µCT analysis, histomorphometry, histology, and fluorescence evaluation. RESULTS: The aiming device could be easily placed in 63 sheep and assured a reproducible, standardized injection area. In four sheep, cardiovascular complications occurred during surgery and pulmonary embolism was detected by computed tomography post surgery in all of these animals. The harvesting and evaluative methods assured a standardized analysis of all samples. CONCLUSIONS: This experimental animal model provides an excellent basis for testing new biomaterials for their suitability as bone augmentation materials. Concomitantly, similar cardiovascular changes occur during vertebroplasties as in humans, thus making it a suitable animal model for studies related to vertebroplasty.

Effect of ventilation technique and airway diameter on bronchial lumen to pulmonary artery diameter ratios in clinically normal beagle dogs.

In dogs, a mean broncho-arterial ratio of 1.45 ± 0.21 has been previously defined as normal. These values were obtained in dogs under general inhalational anesthesia using a single breath-hold technique. The purpose of the study was to determine whether ventilation technique and bronchial diameter have an effect on broncho-arterial ratios. Four healthy Beagle dogs were scanned twice, each time with positive-pressure inspiration and end expiration. For each ventilation technique, broncho-arterial ratios were grouped into those obtained from small or large bronchi using the median diameter of the bronchi as the cutoff value. Mean broncho-arterial ratios obtained using positive-pressure inspiration (1.24 ± 0.23) were statistically greater than those obtained at end expiration (1.11 ± 0.20) P = 0.005. There was a strong positive correlation between bronchial diameter and broncho-arterial ratios for both ventilation techniques (positive-pressure inspiration rs = .786, P < 0.0005 and end expiration rs = .709, P < 0.0005). Mean broncho-arterial ratio for the large bronchi obtained applying positive-pressure inspiration was 1.39 cm ± 0.20 and during end expiration was 1.22 cm ± 0.20. Mean broncho-arterial ratio for the small bronchi obtained during positive-pressure inspiration was 1.08 cm ± 0.13 and during end expiration was 1.01 cm ± 0.13. There was a statistically significant difference between these groups (F = 248.60, P = 0.005). Findings indicated that reference values obtained using positive-pressure inspiration or from the larger bronchi may not be applicable to dogs scanned during end expiration or to the smaller bronchi.

Orbito-nasal cyst in a young European short-haired cat.

PURPOSE: To describe a case of an orbito-nasal cyst in a cat. PROCEDURE: An 18-month-old male European short-haired cat was presented to the Ophthalmology service of the Vetsuisse Faculty, University of Zurich for a subcutaneous swelling in the medial canthal region of the right eye (OD). Ophthalmologic, ultrasound and CT examinations, and fine needle aspiration were performed. After lesion excision, the removed tissue was submitted for histopathology. CT examination was repeated 5 months after removal of the cyst. RESULTS: Ophthalmologic examination revealed a large fluctuant swelling inferonasal to OD. Despite patent lacrimal puncta, only the first few mm of the lacrimal canaliculi could be cannulated. A normal globe with moderate enophthalmos was present. Ultrasound examination showed a well-defined lobulated cyst-like structure in the right orbit, inferonasal and anterior to the eye. CT examination revealed extension of this lesion through the medial orbital wall into the right nasal cavity. Fine needle aspiration confirmed the cystic nature of the lesion. An orbito-nasal cyst was diagnosed. The orbital part of the cyst was dissected from the surrounding tissue and excised from the periosteum in the medial orbital wall defect. Part of the maxillary bone was removed to allow removal of the cyst from the nasal cavity. Histologically, the cyst wall consisted of a single to multilayered, mostly cuboidal epithelium and surrounding connective tissue. Follow-up revealed a good functional result and no recurrence 7 months after cyst removal. CONCLUSIONS: Similar orbito-nasal cystic structures were reported in dogs but not in cats.

Comparison of healing of the osteotomy gap after tibial tuberosity advancement with and without use of an autogenous cancellous bone graft.

OBJECTIVE: To evaluate and compare healing, with and without the use of bone graft, of the gap created during tibial tuberosity advancement (TTA). STUDY DESIGN: Prospective study and case series. ANIMALS: Dogs treated with TTA (n=67). METHODS: Prospective study: Mediolateral radiographic projections (6 weeks and 4 months) after TTA without use of bone graft (group I, n=14) were compared with radiographs of consecutive TTA in which the gap was filled with autologous cancellous bone graft (group II, n=14). Two scoring techniques (A, B) were used. Score A was used to grade the overall osteotomy healing (0=no healing, 4=healed osteotomy). Score B evaluated, independently of each other, healing in 3 sites: proximal to the cage (B1), between cage and plate (B2), and distal to the plate (B3). CASE SERIES: nongrafted TTA (4-25 weeks, n=39) were evaluated for healing (Score A). Data was analyzed using t-tests and ANOVA. Significance was set at P≤.05. RESULTS: Prospective study: Score A, B2, and B3 showed no difference in healing between groups at 6.8 weeks and 4.2 months. Score B1 revealed, in both rechecks, a significantly higher density in group II. case series: Radiographs at 11.59±5.99 weeks scored 3.3 (2-4). No healing related complications were observed. CONCLUSION: The osteotomy gap created during TTA healed within expected time regardless of bone graft use.

Comparison of racemic ketamine and S-ketamine as agents for the induction of anaesthesia in goats.

OBJECTIVE: To compare racemic ketamine and S-ketamine as induction agents prior to isoflurane anaesthesia. STUDY DESIGN: Prospective, blinded, randomized experimental study. ANIMALS: Thirty-one healthy adult goats weighing 39-86 kg. METHODS: Goats were premedicated with xylazine (0.1 mg kg(-1)) intravenously (IV) given over 5 minutes. Each goat was assigned randomly to one of two treatments for IV anaesthetic induction: group RK (15 goats) racemic ketamine (3 mg kg(-1)) and group SK (16 goats) S-ketamine (1.5 mg kg(-1)). Time from end-injection to recumbency was measured and quality of anaesthetic induction and condition for endotracheal intubation were scored. Anaesthesia was maintained with isoflurane in oxygen for 90 minutes. Heart rate, invasive arterial blood pressure, oxygen saturation, temperature, end-tidal carbon dioxide and isoflurane were recorded every 5 minutes. Arterial blood samples were taken for analysis every 30 minutes. Recovery time to recurrence of swallowing reflex, to first head movement and to standing were recorded and recovery quality was scored. Two-way repeated measures anova, Mann-Whitney and a Mantel-Cox tests were used for statistical analysis as relevant with a significance level set at p<0.05. RESULTS: Induction of anaesthesia was smooth and uneventful in all goats. There was no statistical difference between groups in any measured parameter. Side effects following anaesthetic induction included slight head or limb twitching, moving forward and backward, salivation and nystagmus but were minimal. Endotracheal intubation was achieved in all goats at first or second attempt. Recovery was uneventful on all occasions. All goats were quiet and needed only one or two attempts to stand. CONCLUSIONS AND CLINICAL RELEVANCE: S-ketamine at half the dose rate of racemic ketamine in goats sedated with xylazine and thereafter anaesthetised with isoflurane induces the same clinically measurable effects.

Computed Tomography-Derived Occipital-Coccygeal Length and Ilium Wing Distance Correlates with Skin to Epidural and Intrathecal Depths in Dogs.

The current clinical techniques for neuraxial needle placement in dogs are predominantly blind without prior knowledge of the depth required to reach the desired space. This study investigated the correlation and defined the relationship between easily obtainable external landmark variables in the dog; occipital-coccygeal length (OCL) and ilium wings distance (IWD), with the skin to epidural and intrathecal space distances using computed tomography (CT). The CT images of 86 dogs of different breeds were examined in this retrospective observational study. Images of dogs in sternal recumbency were optimized to the sagittal view. The distances between the skin and lumbosacral epidural space (LSE) and skin to sacrococcygeal space (SCE) were measured to the ligamentum flavum surrogate (LFS) line. The distance between the skin and the intrathecal space (ITS) was measured from the skin to the vertebral canal at the interlumbar (L5-L6) space. Measurements of the IWD and OCL were performed on dorsal and scout views, respectively. Linear regression equations and Pearson's correlation coefficients were calculated between variables. Data were reported as mean (standard deviation). Significance was set as alpha < 0.05. After exclusion of four dogs, 82 CT scans were included. The depths were LSE 45 (15) mm, SCE 23 (10) mm, and ITS 50 (15) mm. There was a moderate correlation between OCL with LSE (=14.2 + OCL * 0.05 (r = 0.59, p < 0.0001)), and a strong correlation with ITS (=11.4 + OCL * 0.07 (r = 0.76, p < 0.0001)), while a very weak correlation was found with SCE (=14.0 + OCL * 0.02 (r = 0.27, p < 0.0584)). Similarly, with IWD, there was a moderate correlation with LSE (=10.8 + IWD * 0.56 (r = 0.61, p < 0.0001)), and strong correlation with ITS (=9.2 + IWD * 0.67 (r = 0.75, p < 0.0001)), while a weak correlation was found with SCE (=11.2 + IWD * 0.2 (r = 0.32, p < 0.0033)). Mathematical formulae derived from the multiple regression showed that the body condition score (BCS) improved the relationship between IWD and OCL and the LSE, SCE and ITS, while the addition of body weight was associated with multicollinearity. Further studies are required to determine the accuracy of the algorithms to demonstrate their ability for prediction in a clinical setting.

Comparison of four inflation techniques on endotracheal tube cuff pressure using a feline airway simulator.

OBJECTIVES: The aim of this study was to compare four inflation techniques on endotracheal tube cuff (ETC) pressure using a feline airway simulator. METHODS: Ten participants used four different endotracheal cuff inflation techniques to inflate the cuff of a low-pressure, high-volume endotracheal tube within a feline airway simulator. The simulator replicated an average-sized feline trachea, intubated with a 4.5 mm endotracheal tube, connected to a circle breathing system and pressure-controlled ventilation with oxygen and medical air. Participants inflated the ETC: by pilot balloon palpation (P); by instilling the minimum occlusive volume (MOV) required for loss of airway leaks during mechanical ventilation; until a passive release of pressure with use of a loss-of-resistance syringe (LOR); and with use of a syringe with a digital pressure reader (D) specifically designed for endotracheal cuff inflation. Intracuff pressure was measured by a manometer obscured to participants. The ideal pressure was considered to be between 20 and 30 cmH2O. Data were analysed by Shapiro-Wilk, Kruskal-Wallis and χ2 tests, as appropriate. RESULTS: Participants were eight veterinarians and two veterinary nurses with additional training in anaesthesia. Measured median intracuff pressures for P, MOV, LOR and D, respectively, were 25 cmH2O (range 4-74 cmH2O), 41 cmH2O (range 4-70 cmH2O), 31 cmH2O (range 18-64 cmH2O) and 22 cmH2O (range 20-30 cmH2O). D performed significantly better (P <0.001) than all other techniques, with no difference between the other techniques. CONCLUSIONS AND RELEVANCE: Use of D for cuff inflation achieved optimal cuff pressures. There may be high operator-dependent variability in the cuff pressures achieved with the use of P, MOV or LOR inflation techniques. As such, a cuff manometer is recommended when using any of these techniques.

Caval foramen hernia in a cat.

CASE SUMMARY: A 3-year-old neutered female domestic shorthair cat presented for a 2-week history of hyporexia, lethargy and weight loss. Aspartate aminotransferase, alanine aminotransferase and cholesterol were mildly elevated. Thoracic radiographs identified a lobulated soft tissue opacity in the caudal thorax to the right of midline, with the border effacing the caudal vena cava and broad-based towards the diaphragm. The broad base was suggestive of diaphragmatic hernia, with the other radiographic features and location suggestive of caval foramen hernia. Ultrasound confirmed diaphragmatic hernia with liver herniation. CT showed the herniation of multiple liver lobes and the gallbladder through a defect at the caval foramen. Herniorrhaphy was performed via ventral midline coeliotomy. Following this procedure, the cat's clinical signs resolved and its weight has been regained. RELEVANCE AND NOVEL INFORMATION: To our knowledge, this is the first report of successful caval foramen herniorrhaphy in a cat. Caval foramen hernia is a type of congenital diaphragmatic hernia. The authors suggest that its embryopathology involves defective septum transversum development. The case was detected during the standard diagnostic investigation of non-specific clinical signs. Its radiographic findings may easily be mistaken for a pulmonary mass. Although not seen in our case, caval foramen hernia is commonly associated with caudal vena cava obstruction, which can potentially result in Budd-Chiari-like syndrome.

Ventilated postmortem computed tomography to evaluate the lungs of dogs with and without focal lung lesions.

OBJECTIVE: To identify the optimal ventilation pressure for ventilated postmortem CT assessment of the lungs in cadaveric dogs and compare the optimal ventilation pressures between dogs with and without focal lung lesions. SAMPLE: 12 cadaveric dogs. PROCEDURES: CT was performed with dogs positioned in sternal recumbency within 30 to 180 minutes after death. After orotracheal intubation, lungs were aerated to ventilation pressures of 0, 10, 15, 20, 25, 30, and 35 cm H2O. Lung attenuation measurements were made at 5 predetermined anatomical locations with use of a multi-image analysis graphic user interface tool. Lungs were considered hyperaerated (-1000 to -901 HU), normo-aerated (-900 to -501 HU), poorly aerated (-500 to -101 HU), and nonaerated (-100 to 100 HU) on the basis of lung attenuation values. Optimal ventilation pressure was defined as the pressure at which the percentage of normo-aerated lung was greatest. For analysis, dogs were assigned to one group when focal lung lesions were evident and to another group when lesions were not evident. RESULTS: Median optimal ventilation pressure was significantly higher for those dogs with lung lesions (35 cm H2O), compared with those without (25 cm H2O). CONCLUSIONS AND CLINICAL RELEVANCE: A ventilation pressure of 35 cm H2O may be considered for ventilated postmortem CT to determine the presence of focal lung lesions; however, further investigation is required.

Peripartum clinical manifestations of a mesentericorenocaval shunt in a Burmese cat.

CASE SUMMARY: A 3-year-old entire female Burmese cat was presented for investigation of intermittent lethargy during gestation followed by persistent hypersalivation and ataxia postpartum. The cat had queened three litters in total, with clinical signs worsening during the most recent lactation period. Mild anaemia (26%), hypoglycaemia (2.4 mmol/l; reference interval [RI] 3.9-8.3 mmol/l) and increased postprandial serum bile acids (74 µmol/l; RI <25 µmol/l) were identified on initial bloodwork. Multiphase contrast-enhanced CT identified a mesentericorenocaval portosystemic shunt; this was attenuated surgically with an ameroid constrictor. Clinical signs resolved after surgery. Follow-up 3 months postoperatively revealed normal pre- and postprandial serum bile acids (2 µmol/l and 3 µmol/l, respectively) with repeat CT identifying evidence of shunt attenuation. The cat continued to be healthy and free of clinical signs 12 months postoperatively. RELEVANCE AND NOVEL INFORMATION: Mesentericorenocaval portosystemic shunt morphology has not been previously reported in the cat and should be considered as a differential diagnosis for cats presenting with peripartum onset of malaise, ptyalism or ataxia.

Tasmanian devils with contagious cancer exhibit a constricted T-cell repertoire diversity.

The Tasmanian devil (Sarcophilus harrisii) is threatened by a contagious cancer, known as Devil Facial Tumour Disease (DFTD). A highly diverse T-cell receptor (TCR) repertoire is crucial for successful host defence against cancers. By investigating TCR beta chain diversity in devils of different ages, we show that the T-cell repertoire in devils constricts in their second year of life, which may explain the higher DFTD prevalence in older devils. Unexpectedly, we also observed a pronounced decline in TCR diversity and T cell clonal expansion in devils after DFTD infection. These findings overturned the previous assumption that DFTD did not directly impact host immunity.