Atypically located accessory splenic hemangiosarcoma in a Dog: Diagnostic value of triple-phase computed tomography.

A 10-year-old Cocker spaniel presented with lethargy. Triple-phase computed tomography was obtained with a contrast test bolus at the level of porta hepatis, which revealed a right lower abdominal mass. The mass was not connected to other abdominal organs; however, a linear structure was observed connecting the splenic hilum to the mass, which was suspected to be the feeding vessel. The arterial phase image was obtained again with a contrast bolus at the level of the celiac artery. A prominent contrast-enhanced feeding artery originating from the splenic artery to the mass was observed. Histopathology confirmed an accessory splenic hemangiosarcoma.

Radiologic and computed tomography evaluation of the beaks from three bird species.

This study aimed to evaluate the beaks of three species of birds using radiography and computed tomography (CT). The mean lengths of maxillary and mandibular rostra on radiographs were highest for toco toucan, followed by buff-necked ibis, and least for red-legged seriema birds. The height and width of maxillary and mandibular rostra measured on CT had mean values highest for toco toucans, followed by red-legged seriema, and least for buff-necked ibis. Except for the proximal region of the maxillary rostrum, the HU values were positive for other regions of the maxillary and mandibular rostra in the buff-necked ibis and red-legged seriema and negative in all for the toco toucan.

Arthrographic description of the canine carpal joint cavities and its recesses.

Joint effusion is diagnostically important. The canine carpal joint effusion, which is sometimes difficult to detect clinically, has received less attention in diagnostic ultrasound (US) studies. The aim of the present study was to provide a description of the morphological appearance of the canine carpal joint cavities and recesses using US, radiography, helical computed tomography (CT) and three-dimensional volume rendering technique (3D-VRT) images and to prove the applicability of musculoskeletal US for the detection of artificial carpal joint effusion in dogs. The understanding of the characteristics of these structures in normal patients is essential in the diagnosis. Twenty-eight clinically and radiologically unremarkable canine carpal cadavers of different breeds were examined, representative images were selected and anatomical structures were labelled. The canine carpal joint cavities and in particular its recesses had a complex appearance with a basic structure found in all dogs: Antebrachiocarpal joint: dorsoproximal antebrachiocarpal recess, dorsodistal antebrachiocarpal recess, medial antebrachiocarpal recess, lateral antebrachiocarpal recess and five palmar antebrachiocarpal recesses. Middle carpal joint: two dorsal middle carpal recesses, medial common middle carpal and carpometacarpal recess, lateral common middle carpal and carpometacarpal recess, four palmar middle carpal recesses. The carpometacarpal joint had dorsal and palmar funnel-shaped and irregular, finely tubular extensions, the most prominent ran dorsal to metacarpal III, the maximum distal end represented the proximal metacarpal diaphysis. All recesses presented ultrasonographically as a generalized anechogenic to hypoechoic filled continuation of the articular capsule with an indistinct peripheral hypoechogenic to isoechogenic fine capsule, the synovial-connective tissue interface was difficult to identify. The novel results of this study provide the first morphological description of the ultrasonographic, radiographic and computed tomographic arthrographic appearance of the canine carpal joint cavities and recesses with different injection volumes. The canine carpal joint cavities and in particular its recesses had a complex appearance with a basic structure found in all dogs. The applicability of musculoskeletal US to visualize an artificial carpal effusion has been demonstrated. The results of this study, and in particular US, give the practitioner an advantage in visualizing joint effusion and assist in the decision to perform arthrocentesis.

Physical examination and CT to assess thoracic injury in 137 cats presented to UK referral hospitals after trauma.

OBJECTIVES: The aim of the study was to describe clinical examination and thoracic CT (TCT) findings in cats after trauma, and to identify physical examination findings associated with both abnormalities on TCT and the need for therapeutic interventions. METHODS: A multicentre, retrospective, observational study was conducted. Cats admitted to the participating hospitals with a history of blunt trauma and that underwent TCT were eligible. Data were collected on signalment, history, physical examination, TCT findings and subsequent interventions. RESULTS: In total, 137 cats were included. Road traffic accidents (RTAs) were the most frequently reported cause of trauma (69%). Tachypnoea (32%), pale mucous membranes (22%) and dyspnoea (20%) were the most common abnormal findings on thoracic examination. The most frequently identified thoracic pathologies on TCT were atelectasis (34%), pulmonary contusions (33%), pneumothorax (29%) and pleural effusion (20%). Thoracocentesis was the most commonly performed intervention (12%), followed by chest drain placement (7%). A total of 45 (33%) cats had no physical examination abnormalities but did have abnormalities detected on TCT; six of these cats required interventions. Increasing numbers of thoracic abnormalities on clinical examination were associated with increasing likelihood of having abnormal findings on TCT (odds ratio [OR] 2.04, 95% confidence interval [CI] 1.21-3.44, P = 0.008) and of requiring an intervention (OR 1.82, 95% CI 1.32-2.51, P <0.001). CONCLUSIONS AND RELEVANCE: RTAs were the most common reported cause of blunt trauma. Atelectasis, pulmonary contusions and pneumothorax were the most common abnormalities identified on TCT, and thoracic drainage was the most utilised intervention. TCT may be useful in identifying cats with normal thoracic physical examination findings that have significant thoracic pathology, and a high number of abnormal findings on thoracic examination should raise suspicion for both minor and major thoracic pathology. The results of this study can be used to assist in selecting appropriate cases for TCT after blunt trauma.

Imaging diagnosis: CT characteristics of a retrobulbar hibernoma in a dog.

A 12-year-old female spayed Beagle was referred for investigation of exophthalmos. CT revealed a well-defined, retrobulbar mass causing rostro-dorsal displacement of the left globe. The mass had a mildly heterogeneous precontrast soft tissue attenuation with mild heterogeneous enhancement following iohexol administration. The mass was surgically removed en bloc with an orbital exenteration. Histopathology confirmed the mass to be a hibernoma, a benign tumor of brown adipose tissue. Hibernomas have CT characteristics consistent with both benign and malignant adipose tumors and may be underrecognized by radiologists.

Computed tomography and three dimensional anatomical study of the liver in the chinchilla (Chinchilla lanigera).

Few instances of neoplastic formations in the liver of chinchillas have been found, even though the species is widely used in different scientific experiments. In the present article we investigate the anatomical features of the chinchilla's liver using CT and three dimension (3D) imaging. For the trials we used 12 (six males and six females) clinically healthy chinchillas all at 18 months of age. The animals were positioned in dorsal recumbency. We used Th8 to L2 vertebrae and the sternum as bone markers for the transverse CT study. The investigated anatomical landmarks for the CT coronal study were the vertebrae, costal arch, soft abdominal wall, diaphragm, stomach and the right kidney. 3D reconstructions were accomplished with a specific imaging software. On transverse and coronal CT images, the chinchilla's liver was composed of lobus hepatis sinister lateralis, 'middle lobe'-without proper Latin term in NAV 2017, lobus hepatis dexter and lobus caudatus. The 'middle lobe' was separated into the 'left middle lobe' and the 'right middle lobe'. Lobus hepatis dexter consisted of lobus hepatis dexter medialis and lobus hepatis dexter lateralis. There was an anatomical relation between the liver, fundus ventriculi and corpus ventriculi. Proc. caudatus was in close contact with the right kidney. Vesica fellea was elongated and ellipsoid. 3D reformatted images confirmed the results obtained by transverse and coronal CT studies. The CT density of the liver in HU was 195.6 ± 73.1. The CT and 3D reconstructed images were visualized at high resolution. This data could be used as a basis for further morphological and imaging studies.

Quantitative analysis of the skull in the Japanese wolf (Canis lupus hodophilax) using CT.

In this study using computed tomography (CT), the volumes of the internal cranial cavities, such as the braincase, frontal sinus and tympanic cavity, and the ratio of the volume of each cavity to the skull volume in Japanese wolves were quantified, and CT images of the frontal sinus were observed. The results were then compared with those of other wolf subspecies, including Akita, a dog breed, to clarify the characteristics of the internal cranial cavities in Japanese wolves. The present study revealed that the Japanese wolf had a relatively larger braincase volume and a relatively smaller frontal sinus volume than the wolf ssp. (a group of wild wolf subspecies except the Japanese wolf) and Akita. Moreover, the relative and absolute tympanic cavity volumes of the Japanese wolf and Akita were significantly smaller than those of the wolf ssp. In the CT image or macroscopic observations, the frontal sinuses of the wolf ssp. and Akita were relatively well developed to the caudal and dorsal directions, respectively, compared with that of the Japanese wolf, and the tympanic cavity of the wolf ssp. was more largely swelled ventrally and medially than that of other groups.

CT features of cutaneous and subcutaneous canine mast cell tumors and utility of conventional and indirect lymphography to detect clinically unknown mast cell tumors and to map the sentinel lymph nodes.

Computed tomography is frequently used to stage canine mast cell tumors (MCTs). The aims of this prospective, observational study were to describe the CT features of MCTs, to evaluate the performance of CT in detecting additional or incidental MCTs, to distinguish between cutaneous (cMCT) or subcutaneous (scMCT) MCTs, and to identify one or multiple sentinel lymph nodes (SLNs) by indirect CT lymphography (ICTL). Seventy-two dogs affected by 111 MCTs were included. The recorded parameters were: shape, size, attenuation (Hounsfield units [HU]), location (cutaneous or subcutaneous), and presence of fat stranding. The SLNs were compared with the regional lymph nodes and supplementary MCTs were registered. Mast cell tumors mostly appeared with well-defined margins (89%), round/oval shape (71%), homogeneous enhancement (90%) with a mean postcontrast density of 62.0 ± 23.4 HU and associated with fat stranding (43%). Cutaneous mast cell tumors were more frequently round (P = .003), whereas scMCTs were oval (P = .011) with a larger mean maximal diameter (2.91 ± 1.57 cm vs 1.46 ± 1.28 cm, P = .002) and more feeding vessels (77% vs 39% P = .044). Compared with histopathology, CT accuracy in differentiating cMCTs and sMCTs was 57%, with an interobserver agreement of 88% (three reviewers). Indirect CT lymphography showed the SLN in 82 of 85 (97%) cases, 32% of them not corresponding to the regional node. CT showed additional or incidental MCTs in 23 of 72 (32%) dogs. In conclusion, the common CT appearance of canine cMCTs and scMCTs is reported with some statistical differences between the two categories. CT is useful in identifying clinically undetected MCTs and SLNs, although it shows low accuracy in distinguishing between cMCT and scMCT.

Cervical spine reconstruction after total vertebrectomy using customized three-dimensional-printed implants in dogs.

BACKGROUND: Sufficient surgical resection is necessary for effective tumor control, but is usually limited for vertebral tumors, especially in the cervical spine in small animal neurosurgery. OBJECTIVE: To evaluate the primary stability and safety of customized three-dimensional (3D)-printed implants for cervical spine reconstruction after total vertebrectomy. METHODS: Customized guides and implants were designed based on computed tomography (CT) imaging of five beagle cadavers and were 3D-printed. They were used to reconstruct C5 after total vertebrectomy. Postoperative CT images were obtained to evaluate the safety and accuracy of screw positioning. After harvesting 10 vertebral specimens (C3-C7) from intact (group A) and implanted spines (group B), implant stability was analyzed using a 4-point bending test comparing with groups A and C (reconstituted with plate and pins/polymethylmethacrylate after testing in Group A). RESULTS: All customized implants were applied without gross neurovascular damage. In addition, 90% of the screws were in a safe area, with 7.5% in grade 1 (< 1.3 mm) and 2.5% in grade 2 (> 1.3 mm). The mean entry point and angular deviations were 0.81 ± 0.43 mm and 6.50 ± 5.11°, respectively. Groups B and C significantly decreased the range of motion (ROM) in C3-C7 compared with intact spines (p = 0.033, and 0.018). Both groups reduced overall ROM and neutral zone in C4-C6, but only group B showed significance (p = 0.005, and 0.027). CONCLUSION: Customized 3D-printed implants could safely and accurately replace a cervical vertebra in dog cadavers while providing primary stability.

Reconstructive surgery with an autologous bone graft in a dog with presumptive chronic non-bacterial osteomyelitis.

A 15-year-old Cocker Spaniel was referred to for the evaluation of left forelimb lameness. Radiographic and computed tomography examinations revealed osteolysis of the proximal left third, fourth and fifth metacarpal bones and pathological fractures of the proximal left fourth metacarpal bone. Histopathological examination via bone biopsy did not provide a definitive diagnosis, and the owner elected limb-sparing surgery. The fourth metacarpal bone and digits were amputated. Subsequently, autologous bone grafts were performed on the lytic area of the third and fifth metacarpal bones. The dog showed improvement in gait 7 weeks after reconstructive surgery. Chronic non-bacterial osteomyelitis (CNO) was diagnosed by exclusion. To the best of our knowledge, CNO has not been previously reported in dogs.

Three-dimensional modelling and morphometric analysis of skull of badger (Meles meles) with computed tomography images.

BACKGROUND: Morphometric measurements help to understand the skull morphology in different animal species, detect skull deformations and figure out their causes. OBJECTIVES: The aim of this study is to make a three-dimensional (3D) modelling of the badger skull using computed tomography, to show its anatomical structures and to reveal the morphometric measurement values. METHODS: Skull measurements were carried out using a digital calliper at 27 measurement points based on metric measurement points. After the scanned images were stored in Digital Imaging and Communications in Medicine format, they were transferred to MIMICS 20.1 (The Materialize Group) programme and 3D models the skulls were created. The surface area and volume values of the skulls were calculated on these models. RESULTS: The volume and surface area parameters were expressed as mean ± SE. Four different indices were calculated using osteometric measurements. Statistical analyses were made by determining the mean value and standard deviation of the examined properties and the correlation coefficients among these properties. In the metric measurement points taken as a basis, the longest measurement in the skulls was the total length and its mean value was 124.60 ± 0.64 mm. The shortest measurement was the breadth dorsal to the external auditory meatus, and its mean value was 6.75 ± 0.24 mm. CONCLUSIONS: Consequently, statistical differences in the craniometric values of badgers' skulls were determined by using CT and 3D modelling software. In addition, it was concluded that the badger skull can be easily distinguished from other carnivore species by carrying out morphometric measurements.

Introducing a novel intraoral mandibular nerve block technique for loco-regional analgesia in camels (Camelus dromedarius): a cadaveric study using computed tomography.

The aim of this study was to introduce a novel intraoral technique for performing mandibular nerve blocks in dromedary camels (Camelus dromedarius). In this study, 18 adult camel skulls of varying ages and breeds were examined to determine the position of the mandibular foramen. Using a Vernier caliper, three dimensions in millimeters were measured: (1) the distance between the mandibular foramen (MF) and the caudal edge of the third molar tooth at the occlusal surface level, (2) the distance between the MF and the rostral edge border of the mandible's ramus (RER) at the occlusal surface level, and (3) the distance between the MF and the ventral margin border of the mandible (VM). The technique was evaluated using five intact camel cadaver heads (n = 5), and a total of ten mandibular nerve blocks were described. An 18-gauge 80-mm Tuohy needle was inserted into the mouth commissure and advanced caudally while injecting a saline-methylene blue solution. The accuracy of the injection was confirmed through the infiltration of the contrast dye into the target area using computed tomography (CT) and post procedural dissection. Anatomical study of the mandibular nerve site was performed to aid the blind insertion of the needle. The findings contribute to the development of veterinary anesthesia techniques and provide anatomical considerations for clinicians performing oral surgeries in sedated camels. The results demonstrated the successful implementation of the intraoral technique, highlighting its efficacy and reliability in achieving local anesthesia for oral surgeries involving the lower jaw and teeth in sedated camels. Further research studies are needed to evaluate the long-term efficacy and safety of the technique and to compare it with existing approaches.

Computed tomographic dimensions and densities of the normal eye in Jeju horses.

This study aimed to describe the computed tomographic (CT) dimensions and the contrast attenuation of the eye in Jeju horses and Thoroughbreds. We evaluated the CT images of 10 Jeju horses and 6 Thoroughbreds without ocular abnormalities to assess the ocular dimensions and contrast attenuation. The following measurements showed significant differences between Jeju horses and Thoroughbreds (P<0.05): the diameters of the lens, globe, posterior segment, orbital fossa, and lateromedial distance of the anterior chamber; and the Hounsfield units of the vitreous body. This study describes the CT anatomical characteristics of Jeju horses and Thoroughbreds and the differences between the two breeds and provides useful information for understanding and evaluating of the eyes of Jeju horses through a CT scan.

Usefulness of combining computed tomography and air sac fluid examination to rule out aspergillosis: case study in two gentoo penguins (Pygoscelis papua) with respiratory clinical signs.

Pulmonary aspergillosis occurring in captive penguins living in zoos and aquariums is a fatal disease owing to its high mortality rate. On conducting computed tomography, two gentoo penguins (Pygoscelis papua) with respiratory clinical signs that were housed at an aquarium in Hokkaido, Japan were found to have a certain amount of fluid in their air sacs. This fluid was collected and cultured for bacteria and fungi, the results of which both came back negative. These results enabled us to rule out bacterial infection or aspergillosis and supported our decision not to administer antibacterial and antifungal drugs. Overall, the combination of computed tomography and air sac fluid examination was useful for ruling out bacterial infection or aspergillosis in penguins with respiratory clinical signs.

Receiver operating characteristics of computed tomography (CT) compared to cystoscopy in diagnosis of canine ectopic ureters: Thirty-five cases.

OBJECTIVE: The aim of the study was to determine receiver operating characteristics (ROC) of computed tomographic excretory urography (CTEU) in predicting cystoscopic findings of ureteral anatomy. STUDY DESIGN: Retrospective cohort study. ANIMALS: Thirty-five client-owned dogs. METHODS: The medical records of dogs referred for suspected ectopic ureters were reviewed. Inclusion criteria included CTEU findings reported by board-certified radiologists, followed by rigid cystoscopy with or without ureteral cystoscopic laser ablation (CLA). Data included signalment, urinary incontinence degree, body condition score, weight, degree of colon distension, CTEU and cystoscopy findings. ROC analysis was used to compare CT-predicted ureteral orthotopia/ectopia to cystoscopy findings. Additionally, ROC of CT predicted ureteral orifice locations was analyzed. Regression covariate analysis was performed to identify factors that may have influenced accuracy of diagnosis. RESULTS: The ability of CT to identify a normal and intra-or extramural ectopic ureters conclusively and correctly was 13/26 (50%) and 32/41(78%), respectively. Sensitivity and specificity of identifying extramural versus intramural ureters was 2/7 versus 30/46 (29 vs. 65%) and 61/63 versus 17/24 (97 vs. 71%), respectively. Ectopic orifice determination sensitivity and specificity varied widely depending on location from 0% to 76% and 67% to 97%, respectively. Covariate analysis failed to identify interfering factors. CONCLUSIONS: CT did not accurately predict anatomy of ureters; CT findings may need confirmation by cystoscopy and possibly intraoperative fluoroscopy prior to determining if CLA is indicated or not. CLINICAL SIGNIFICANCE: Our results may be of importance for surgeons interpreting the CTEU findings. CTEU prediction of the location of the ureteral orifice shows low sensitivity especially in or close to the urethral sphincter area.

Development of three-dimensional cardiac models from computed tomography angiography.

Three-dimensional (3D) modeling and printing is an emerging technology in veterinary cardiovascular medicine allowing the fabrication of anatomically correct patient-specific models. These patient-specific models can be used for a wide range of purposes including medical teaching, assessment of cardiac function and movement of valve leaflets, design and assessment of devices created for interventional procedures, and pre-surgical planning [1-3]. Additionally, these 3D models can facilitate communication between the clinical team and the patient's owner. The process of creating 3D models starts with acquiring volumetric imaging data sets of the area of interest. Three-dimensional modeling and printing are reliable when high-quality volumetric imaging data are used to create these models. Currently, only ungated- and electrocardiogram (ECG)-gated computed tomography (CT), cardiac magnetic resonance imaging (CMRI), and 3D echocardiography provide the volumetric data sets needed to create these 3D models. These imaging data sets are imported into a software or open-source freeware platform and then segmented to create a virtual 3D model. This virtual 3D model can be further refined using computer-aided design (CAD) software and then be printed to create a physical 3D model. Cardiovascular 3D modeling and printing is a new medical tool which allows us to expand the way we plan interventional procedures, practice interventional skills, communicate with the medical team and owner, and teach future veterinarians.

Computed tomography features and prevalence of focal diaphragmatic mineralization in 300 dogs.

A focal area of mineral attenuation is commonly observed in the diaphragmatic crura of canine patients undergoing a thoracic CT. There is no mention of this finding in either the human or veterinary medicine literature. This retrospective study evaluates 300 canine thoracic CT studies with the aim of describing the CT appearance of this finding and establishing a prevalence in a large cohort of dogs. The presence of the mineral focus and its CT characteristics, including length, attenuation, and appearance, were recorded and correlated with the patient's signalments and anamnesis. The focus was observed in 43 of 300 studies (14.3%). The most common appearance was a thin, millimetric, toothpick-like mineral attenuating structure in the confluence of the diaphragmatic crura, just ventral to the aorta. There was no association with adjacent potentially pathological changes. A significant correlation was found between the presence of the focus and the patient's body weight (P = .03), as well as with a brachycephalic conformation (P = .03). This focus of mineralization represents a relatively common incidental finding in the canine diaphragm and has no evident association with pathology.

Inspection of chicken wings and legs for animal welfare monitoring using X-ray computed tomography, visual examination, and histopathology.

In broiler chickens, fractures of wings and legs are recorded at poultry slaughterhouses based on the time of occurrence. Prekilling (PRE) fractures occur before the death of animal, so the chicken was still able to experience pain and distress associated with the injury (an animal welfare issue). Postkilling (POST) fractures occur when the chickens are deceased and fully bled-out and consequently unable to feel pain (not an animal welfare issue). Current practice dictates that fractures are recognized visually and recorded by the animal welfare officers as mandated by European Union and/or national regulations. However, new potential monitoring solutions are desired since human inspection suffers from some significant limitations including subjectivism and fatigue. One possible solution in detecting injuries is X-ray computed tomography (CT) scanning and in this study we aim to evaluate the potential of CT scanning and visual inspection in detecting limb fractures and their causes. Eighty-three chicken wings and 60 chicken legs (n = 143) were collected from a single slaughterhouse and classified by an animal welfare officer as PRE, POST or healthy (HEAL). Samples were photographed and CT scanned at a veterinary hospital. The interpretation of CT scans along with photographs took place in 3 rounds (1. CT scans only, 2. CT scans + photographs, 3. photographs only) and was performed independently by 3 veterinarians. The consistency of the interpretation in 3 rounds was compared with the animal welfare officer's classification. Furthermore, selected samples were also analyzed by histopathological examination due to questionability of their classification (PRE/POST). In questionable samples, presence of hemorrhages was confirmed, thus they fit better as PRE. The highest consistency between raters was obtained in the 2nd round, indicating that interpretation accuracy was the highest when CT scans were combined with photographs. These results indicate that CT scanning in combination with visual inspection can be used in detecting limbs fracture and potentially applied as a tool to monitor animal welfare in poultry slaughterhouses in the future.

Computed tomographic characteristics of confirmed and presumed noncutaneous pythiosis in 25 dogs.

Pythium insidiosum is an aquatic oomycete that causes granulomatous infection in dogs, most commonly cutaneous and gastrointestinal. Ultrasonographic characteristics of gastrointestinal pythiosis have been described; occasionally, CT is utilized in the clinical setting, and CT features of pythiosis have not been published. The purpose of this retrospective, multicenter, descriptive study is to describe CT characteristics of noncutaneous canine pythiosis. The following CT parameters were recorded: lesion anatomic location, number, shape, margination, size, attenuation pre- and postcontrast, enhancement pattern, lymph nodes affected, other lesions identified, and presence of peritoneal effusion or steatitis. Descriptive statistics demonstrating the frequency of lesion appearances were performed. Twenty-five dogs with noncutaneous pythiosis lesions that underwent CT were included; 19 had primarily gastrointestinal infections, four primarily arterial infections, one intrathoracic and intra-abdominal infection, and one primary pulmonary infection. In dogs with primary gastrointestinal infection, lesions were most common at the ileocolic junction and were most frequently focal, well-defined, moderate to marked circumferential wall thickening that was homogeneous and smoothly marginated precontrast, with moderate heterogeneous contrast enhancement. Most dogs had involvement of multiple gastrointestinal regions. Of four dogs with primary arterial involvement, three had large aneurysmal dilatations of the cranial mesenteric artery with severe mural thickening. All dogs had regional lymphadenopathy, which was variable but generally mild. Nine dogs had peritoneal effusion; six dogs had steatitis. CT features of pythiosis can overlap with neoplasia, but pythiosis should be considered as a differential, especially in young dogs. Findings supported using CT as an adjunct imaging test for increasing clinical suspicion of noncutaneous pythiosis.

Presumed mediastinal cysts have a low prevalence in canine thoracic computed tomographic studies.

Mediastinal cysts (MCs) are rare lesions that can arise from embryonic remnants of various mediastinal structures. MCs usually are incidental findings in dogs and cats; however, they can reach a mass-like appearance. The description of MCs on CT in dogs is limited. This retrospective, single-center, descriptive, prevalence study aimed to determine the prevalence of presumed mediastinal cysts (PMCs) in dogs and assess their CT characteristics. Dogs that underwent a thoracic CT scan from January 2019 to August 2021 were included. CT images were evaluated for the presence of PMCs by two diagnostic imaging interns, two last year diagnostic imaging residents, and a board-certified veterinary radiologist. Number, location, margins, shape, volume, size, mass effect, and attenuation values of PMCs were assessed. A total of 866 CT scans were reviewed, and 49 PMCs were identified. The prevalence of PMCs in dogs was 5.66%. English Bulldog and mixed-breed dogs were subjectively overrepresented; however, the possibility of population bias could not be excluded. PMCs were subjectively more frequently observed in male dogs. The PMCs were predominantly round, small, solitary fluid-filled findings localized in the cranioventral mediastinum, with well-defined margins, homogeneous attenuation, and no contrast enhancement. The median attenuation value was 6.32 HU (range: -20.16 to 23.45 HU) precontrast and 7.58 HU (range: -2.45 to 20.79 HU) postcontrast, and the median volume was 1.19 cm3 (range: 0.02-45.32 cm3). Although the prevalence of PMCs was low in our sample population, findings supported prioritizing a differential diagnosis of incidental PMC for dogs with the above imaging characteristics.