COMPUTED TOMOGRAPHY BRONCHIAL LUMEN TO PULMONARY ARTERY DIAMETER RATIO IN DOGS WITHOUT CLINICAL PULMONARY DISEASE

Bronchiectasis is diagnosed in humans using multiple computed tomography (CT) criteria, the most important being dilatation of the bronchi. The most widely used criterion for detection of bronchial dilatation is a bronchial lumen to pulmonary artery diameter (bronchoarterial [BA]) ratio >1.0. No studies have been performed to determine the BA ratio in normal dogs. Thoracic CT images of 24 dogs without clinical pulmonary disease were reviewed. The BA ratio of the lobar bronchi of the left cranial (cranial and caudal parts), right cranial, right middle, left caudal, and right caudal lung lobes was measured. The mean of the mean BA ratio for all dogs was 1.45±0.21 (99% confidence interval [CI]=1.34–1.56). The mean of the mean BA ratio as determined by lung lobe was 1.45±0.04 (99% CI=1.41–1.49). The range of individual BA ratios was 0.8–2.0. There was no significant difference in mean BA ratios as a function of lung lobe ( P =0.60). The BA ratio in these clinically normal dogs was consistent and may be a useful tool in evaluating for bronchiectasis on CT images. BA ratios >2.0 were not identified in this population, suggesting a threshold to differentiate normal from abnormal bronchi.     

ACCURACY OF A COMPUTED TOMOGRAPHY BRONCHIAL WALL THICKNESS TO PULMONARY ARTERY DIAMETER RATIO FOR ASSESSING BRONCHIAL WALL THICKENING IN DOGS

Computed tomography is increasingly being used in veterinary medicine to evaluate animals with pulmonary signs such as coughing, tachypnea, and exercise intolerance, however, a quantitative measure of bronchial wall thickening has yet to be validated in veterinary medicine. Canine chronic bronchitis is a disease that is characterized histologically by thickening of the bronchial walls. Thoracic CT images of 16 dogs with chronic bronchitis and 72 dogs presenting for conditions unrelated to cough were evaluated. A ratio comparing the bronchial wall thickness to the adjacent pulmonary artery diameter was obtained in the right and left cranial and caudal lung lobes. There was no significant difference in dogs with chronic bronchitis or unaffected dogs between the left and right hemithorax, patient weight, patient age, image slice thickness, or CT machine used. Dogs with chronic bronchitis were found to have a significantly greater ratio than unaffected dogs (P < 0.001). The ratios in the cranial lung lobes were found to be significantly greater than the caudal lung lobes in both chronic bronchitis and unaffected dogs (P < 0.001). A receiver operating characteristic curve of the ratios in the cranial lung lobes had an area under the curve of 0.912, indicating high accuracy in predicting for bronchial wall thickening. A ratio of ≥0.6 in the cranial lung lobes was found to have a sensitivity of 77% and specificity of 100% in predicting for the presence of chronic bronchitis, and we propose using this cut‐off as supportive of bronchial wall thickening on CT.     

COMPARISON OF FLUOROSCOPY AND COMPUTED TOMOGRAPHY FOR TRACHEAL LUMEN DIAMETER MEASUREMENT AND DETERMINATION OF INTRALUMINAL STENT SIZE IN HEALTHY DOGS

Tracheal collapse is a progressive airway disease that can ultimately result in complete airway obstruction. Intraluminal tracheal stents are a minimally invasive and viable treatment for tracheal collapse once the disease becomes refractory to medical management. Intraluminal stent size is chosen based on the maximum measured tracheal diameter during maximum inflation. The purpose of this prospective, cross‐sectional study was to compare tracheal lumen diameter measurements and subsequent selected stent size using both fluoroscopy and CT and to evaluate inter‐ and intraobserver variability of the measurements. Seventeen healthy Beagles were anesthetized and imaged with fluoroscopy and CT with positive pressure ventilation to 20 cm H₂O. Fluoroscopic and CT maximum tracheal diameters were measured by three readers. Three individual measurements were made at eight predetermined tracheal sites for dorsoventral (height) and laterolateral (width) dimensions. Tracheal diameters and stent sizes (based on the maximum tracheal diameter + 10%) were analyzed using a linear mixed model. CT tracheal lumen diameters were larger compared to fluoroscopy at all locations (P‐value < 0.0001). When comparing modalities, fluoroscopic and CT stent sizes were statistically different. Greater overall variation in tracheal diameter measurement (height or width) existed for fluoroscopy compared to CT, both within and among observers. The greater tracheal diameter measured with CT and lower measurement variability has clinical significance, as this may be the imaging modality of choice for appropriate stent selection to minimize complications in veterinary patients.     

COMPUTED TOMOGRAPHIC CHARACTERISTICS OF THE CISTERNA CHYLI IN DOGS

Previous lymphangiographic studies have investigated the use of computed tomography (CT) for characterizing the thoracic duct and its tributaries in dogs. However, there is limited published information on the appearance of the canine cisterna chyli using CT. The objective of this retrospective study was to describe the features of the canine cisterna chyli in pre‐ and post‐contrast abdominal CT studies. The presence, location, shape, maximum width, size compared with the aortic diameter (Ao:cisterna chyli ratio) and mean attenuation of the cisterna chyli were recorded from archived abdominal CT scans of 30 dogs. Breed, age, sex and neutering status were also noted. A cisterna chyli was identified in 26 of the dogs (87%). In 22 cases a cisterna chyli could be reliably identified prior to intravenous contrast administration and in all 26 cases in postcontrast images. The cisterna chyli was most commonly located right dorsolateral to the abdominal aorta between L1 and L4. Shape varied on transverse images from crescent‐like to globular and maximum diameters ranged from 5 to 9 mm. The Ao:cisterna chyli ratio varied between 0.29 and 0.71 (mean value—males: 0.32; females: 0.38). On pre‐contrast images the mean Hounsfield units were 21.3HU (range: –3.8 to 64.25). Mild enhancement of the cisterna chyli post‐contrast was observed in 24 dogs (80%). Findings supported the use of pre‐ and post‐contrast abdominal CT as a non‐invasive method for assessing qualitative and quantitative characteristics of the canine cisterna chyli.     

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 r_s = .786, P < 0.0005 and end expiration r_s = .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.     

CONTRAST-ENHANCED COMPUTED TOMOGRAPHIC IMAGING OF THE AUDITORY TUBE IN MESATICEPHALIC DOGS

Computed tomography after contrast medium injection was performed in three mesaticephalic canine cadavers to image the auditory tube. Cadavers were positioned in lateral recumbency for imaging. A myringotomy incision was made in the left tympanic membrane of each dog, and contrast medium was infused into the ear canal and middle ear through a balloon-tip catheter. With this method, contrast medium filled the left bulla and auditory tube in all three cadavers. Computed tomography following contrast medium injection was effective for evaluation of the canine auditory tube. Future studies are required to determine the usefulness, as well as the safety, of this procedure in the evaluation of the auditory tube in other breeds of dogs as well as dogs with otitis     

COMPUTED TOMOGRAPHIC APPEARANCE OF PRIMARY LUNG TUMORS IN DOGS

Canine primary lung tumors typically appear radiographically as a well‐circumscribed solitary mass in the periphery of a caudal lung lobe. Consolidated and diffuse forms of primary lung tumors have also been described. Nineteen dogs with computed tomographic (CT) images of the thorax and a histological diagnosis of primary lung tumor (17 primary carcinomas and two primary sarcomas) were evaluated retrospectively to characterize the CT findings. All primary lung tumors were bronchocentric in origin with internal air bronchograms. The bronchi were typically narrowed, displaced, and often obstructed by the tumor. Eighteen of 19 (95%) of the tumors were solitary and there was one pneumonic/alveolar form. Most solitary tumors were well circumscribed (17/18), located in the central to periphery of the lung (14/18), and in a cranial or caudal lobe (16/19). Most primary lung tumors (11/17) had mild to moderate heterogeneous contrast enhancement. Five of 19 dogs (26%) had evidence of pulmonary metastasis. Internal mineralization (3/19) and tracheobronchial lymphadenopathy (4/19) were also identified. On CT examination, solitary, well circumscribed, bronchocentric masses with internal air bronchograms are consistent with a primary pulmonary tumor in dogs.     

A COMPARISON OF RADIOGRAPHIC AND COMPUTED TOMOGRAPHIC FINDINGS IN 31 DOGS WITH MALIGNANT NASAL CAVITY TUMORS

Nasal cavity radiographs and CT images from 31 dogs with nasal cavity cancer were compared. All dogs had abnormal clinical signs relating to -nasal cancer and histologic confirmation of malignant nasal cavity neoplasia. No dog had cyto reductive surgery prior to imaging. All radiographic and CT examinations were abnormal. CT was more accurate than radiographs in identifying unilateral versus bilateral nasal cavity disease and tumor extension into adjacent structures such as the cranial cavity, hard palate, and pterygopala-tine fossa. The improved accuracy of CT in these respects was not of benefit in the confirmation of nasal cavity disease because radiographs were abnormal in every instance. However, CT may be useful for more accurate tumor staging, predicting possible treatment-related complications, and planning of surgery and radiation therapy. It was also determined that one dorsally located radiation therapy portal bounded laterally by the medial ocular canthi, as described in previous reports, would not have been adequate for encompassing all abnormal tissue in 28 of the 31 dogs evaluated.     

COMPARISON OF COMPUTED TOMOGRAPHIC AND PATHOLOGIC FINDINGS IN 17 DOGS WITH PRIMARY ADRENAL NEOPLASIA

The CT appearance of canine adrenal masses has been reported, but associations between imaging features and pathologic features of these lesions have not been investigated in detail. The purpose of this study was to test associations between different types of adrenal neoplasia and their CT and pathologic features. A retrospective cross‐sectional study was performed and inclusion criteria were histologic diagnosis of primary adrenal neoplasia, contrast‐enhanced CT examination of the abdomen and surgical resection of the mass or necropsy examination. For all included dogs, CT images and histopathologic specimens were reviewed independently by two veterinary radiologists and a veterinary pathologist, respectively. Seventeen dogs met inclusion criteria. Diagnoses were adenocarcinoma in nine (53%) dogs, pheochromocytoma in five (29%) dogs, and adenoma in three (18%) dogs. Pheochromocytoma was associated with CT signs of vascular invasion (likelihood ratio = 4.8, 95% CI = 1.3–18.3, P = 0.03) and macroscopic vascular invasion (likelihood ratio = 9.6, 95% CI = 1.4–65.9, P = 0.02). There was excellent agreement between signs of vascular invasion in CT images and vascular invasion at surgery or necropsy (kappa = 0.86, P = 0.001). A peripheral contrast‐enhancing rim in delayed postcontrast CT images was associated with fibrous encapsulation of the tumor (kappa = 0.53, P = 0.05), and a heterogeneous pattern of contrast distribution in delayed postcontrast CT images was associated with adrenal hemorrhage or infarction on histological examination (kappa = 0.45, P = 0.05). Findings indicated that CT enabled assessment of adrenal neoplasia features that reflected their biological behavior and pathological findings, however overlapping characteristics between tumor types limited the potential for reliably distinguishing them based on CT alone.     

THREE-DIMENSIONAL HELICAL COMPUTED TOMOGRAPHIC ANGIOGRAPHY OF THE LIVER IN FIVE DOGS

The objective of this study was to develop a simple, safe, minimally invasive protocol to evaluate the hepatic vasculature. Five purpose-bred Beagle dogs underwent noncontrast-enhanced computed tomographic scan of the entire abdomen. A dynamic, nonincremental computed tomography scan at the level of T11 was then performed using a test bolus of contrast medium to determine time to peak opacification and to aid in the calculation of scan delay. The time to peak arterial enhancement ranged from 2.0 to 7.0 s, with a median of 2.0 s. The time to peak portal venous enhancement ranged from 23.0 to 46.0 s, with a median of 32.0 s. Scan delay for arterial opacification ranged from 0 to 5.0 s, with a median of 0 s. Scan delay for the portal phase of opacification ranged from 6.0 to 21.0 s, with a median of 17.0 s. Using this information, two separate computed tomographic studies were used to image the arterial and portal venous phases of circulatory opacification, respectively. The dogs were hyperventilated to prevent breathing motion during the scan, each of which required approximately 20 s. A power injector was used to inject diatrizoate meglumine (128 mg I/kg) through an 18-gauge cephalic vein catheter at a rate of 5 ml/s. Scanning was initiated after the appropriate scan delay to optimize the specific phase of vascular filling. Maximum intensity projections allowed clear delineation of the hepatic arteries and the portal venous system, while eliminating overlying structures that might interfere with image analysis. Time/density curves were generated, and the time needed for each study was recorded. Hepatic arteries and portal veins were clearly visualized in all dogs. Parenchymal opacification was also observed.     

EVALUATION OF THE URETER AND URETEROVESICULAR JUNCTION USING HELICAL COMPUTED TOMOGRAPHIC EXCRETORY UROGRAPHY IN HEALTHY DOGS

Abdominal computed tomography (CT) using a protocol designed for evaluation of the ureters was performed on six normal purpose-bred research dogs. After noncontrast CT, a postcontrast scan was performed 3 min post midpoint of injection of 400 mgI/kg body weight of diatrizoate meglumine/sodium. Ureteral and ureterovesicular junction anatomy were readily assessed with minimal patient preparation. The ureters were similar in size to reported values and the renal pelvis, ureter, and ureterovesicular junction were easily identified on both noncontrast and contrast-enhanced scans. There was a significant relationship between bladder volume and interureterovesicular junction distance but not between bladder volume and ureterovesicular junction to internal urethral orifice distance. A reliable bony landmark for the identification of the internal urethral orifice could not be determined. The results of this preliminary study of normal anatomy should facilitate the clinical use of CT in the evaluation of ureteral disease (e.g., ureteral ectopia).     

MULTIDETECTOR‐ROW COMPUTED TOMOGRAPHY PATTERNS OF BRONCHOESPHAGEAL ARTERY HYPERTROPHY AND SYSTEMIC‐TO‐PULMONARY FISTULA IN DOGS

Anomalies involving arterial branches in the lungs are one of the causes of hemoptysis in humans and dogs. Congenital and acquired patterns of bronchoesophageal artery hypertrophy have been reported in humans based on CT characteristics. The purpose of this retrospective study was to describe clinical, echocardiographic, and multidetector computed tomography features of bronchoesophageal artery hypertrophy and systemic‐to‐pulmonary arterial communications in a sample of 14 dogs. Two main vascular patterns were identified in dogs that resembled congenital and acquired conditions reported in humans. Pattern 1 appeared as an aberrant origin of the right bronchoesophageal artery, normal origin of the left one, and enlargement of both the bronchial and esophageal branches that formed a dense network terminating in a pulmonary artery through an orifice. Pattern 2 appeared as a normal origin of both right and left bronchoesophageal arteries, with an enlarged and tortuous course along the bronchi to the periphery of the lung, where they communicated with subsegmental pulmonary arteries. Dogs having Pattern 1 also had paraesophageal and esophageal varices, with the latter being confirmed by videoendoscopy examination. Authors conclude that dogs with Pattern 1 should be differentiated from dogs with other congenital vascular systemic‐to‐pulmonary connections. Dogs having Pattern 2 should be evaluated for underlying pleural or pulmonary diseases. Bronchoesophageal artery hypertrophy can be accompanied by esophageal venous engorgement and should be included in the differential diagnosis for esophageal and paraesophageal varices in dogs.     

COMPUTED TOMOGRAPHIC AND RADIOGRAPHIC CHARACTERISTICS OF AORTIC LESIONS IN 42 DOGS WITH SPIROCERCOSIS

Spirocerca lupi is a common cause of vomiting, regurgitation, and sudden death in dogs that live in tropical or subtropical regions. Sudden death due to aortic rupture may occur with no preceding clinical signs. The purpose of this prospective study was to compare radiographic and computed tomographic (CT) characteristics of aortic lesions in a cohort of 42 dogs with endoscopically confirmed spirocercosis. Dorsoventral and right lateral recumbent thoracic radiographic findings were compared with pre‐ and postcontrast thoracic CT findings. Aortic mineralization was detected using CT in 18/42 dogs (43%). Three dogs had faint diffuse aortic wall mineralization. Using CT as the reference standard, radiographs had a sensitivity and specificity of 6% and 96%, respectively, for detecting aortic mineralization. A total of 20 aortic aneurysms were detected using CT in 15/42 dogs (36%). Using CT as the reference standard, radiographs had a sensitivity and specificity of 86% and 56%, respectively, for detecting aortic aneurysms. Respiratory motion, aortic displacement by esophageal masses and Spirocerca nodules adjacent to the aorta mimicked aneurysm formation on radiographs. Aortic thrombi were seen in two dogs in postcontrast CT images. Findings from this study indicated that aortic mineralization and aneurysm formation are common in dogs with spirocercosis. Findings also supported the use of pre‐ and postcontrast CT as effective methods for detecting and characterizing these lesions.     

THE COMPUTED TOMOGRAPHIC APPEARANCE OF ACUTE THORACOLUMBAR INTERVERTEBRAL DISC HERNIATIONS IN DOGS

The appearance of herniated intervertebral disc material in the thoracolumbar vertebral canal was evaluated in 23 dogs using computed tomography (CT). The images were then compared with the myelographic and surgical findings. The normal spinal cord, outlined by epidural fat over intervertebral disc spaces, was of intermediate attenuation on transverse CT images. Herniated disc material was identified in all animals as a heterogeneous hyperattenuating extradural mass. The attenuation of the disc material increased with the degree of mineralization. In seven dogs, the herniated material was only slightly more attenuating than the spinal cord. In these dogs, small fragments of mineralized disc material and significant hemorrhage were found in the epidural space at surgery. In dogs with a long standing history of disc herniations, disc material identified in the vertebral canal had a more hyperattenuating and homogeneous appearance than recently herniated disc material. We conclude that mineralized, herniated disc material and hemorrhage can be identified quickly and safely in dogs using CT.     

EVALUATION OF THE GASTROINTESTINAL TRACT IN DOGS USING COMPUTED TOMOGRAPHY

Abdominal computed tomography (CT) studies of 19 dogs with no history or clinical signs of gastrointestinal disease, and two dogs with a histological diagnosis of gastrointestinal neoplasia were examined retrospectively. Gastrointestinal segments were evaluated subjectively for conspicuity, contrast enhancement, and wall layering after contrast medium administration. In dogs without gastrointestinal disease, there were 62.8% of gastrointestinal segments (serosa to serosa) and 77.7% of gastrointestinal walls (serosa to mucosa) visualized. Wall layering on postcontrast images was seen in 21.8% of gastrointestinal segments. There was significant association between gastrointestinal diameter and wall thickness. There was significant association between weight and gastrointestinal wall thickness in the following regions: gastric fundus, gastric body, gastric pylorus, gastric pyloric antrum, duodenal cranial flexure, jejunum and ascending colon, and between patient weight and gastrointestinal diameter in cranial duodenal flexure, descending duodenum, transverse duodenum, ascending duodenum, and jejunum. Measurements acquired from CT studies correlated well with previously published normal reference ranges for radiographic and ultrasonographic studies. Gastrointestinal neoplasia, diagnosed in two dogs, had a gastrointestinal wall thickness greater than the range of the dogs without gastrointestinal disease. Computed tomography offers identification of the gastrointestinal tract segments in dogs, allows for evaluation of gastrointestinal diameter and aids in investigation of gastrointestinal wall thickness.     

COMPUTED TOMOGRAPHIC FEATURES OF SKULL OSTEOMYELITIS IN FOUR YOUNG DOGS

Computed tomography (CT) features of four immature to young adult dogs with osteomyelitis of the skull are described. Trauma or bite wounds were the cause of infection and Staphylococcus aureus was the most common pathogen. CT features were a combination of soft tissue thickening, bone lysis, and bone proliferation. Bone lysis was extensive in some dogs with a moth-eaten appearance and involved the calvarium, base of the skull, the frontal sinuses, and the temporomandibular joint. In other dogs it was more focal with thinning of the bone rather than complete lysis. Bone proliferation also varied in appearance from irregular palisading or spiculated to expansion and septation of the frontal bone. Sequestrum formation was seen in one dog. Widespread infection in one dog involved the tympanic bullae and the temporomandibular joint. Lysis of the calvarium resulted in bacterial meningitis in two dogs. One dog was euthanized and three were treated with surgical curettage of the affected bone and antibiotic therapy which resulted in resolution of the clinical signs in one dog whereas two dogs had recurrent disease. CT was very helpful for characterizing extent and localization of the infection. Despite the aggressive CT features, osteomyelitis should be considered especially in young animals with a history of trauma or bite wounds. The pathophysiology of skull bone infections is discussed.     

COMPARISON OF TRANSVERSE COMPUTED TOMOGRAPHIC EXCRETORY UROGRAPHY IMAGES AND MAXIMUM INTENSITY PROJECTION IMAGES FOR DIAGNOSING ECTOPIC URETERS IN DOGS

Computed tomographic maximum intensity projection (MIP) images have been shown to improve reader confidence in their diagnoses and to improve detection of vascular structures and pulmonary nodules. The objectives of this method comparison study were to compare transverse source computed tomographic excretory urography (CTEU) images to two, five, and 10 slab thick MIP images for diagnosing canine ectopic ureters, compare reader confidence, and evaluate interobserver agreement. Two board‐certified veterinary radiologists and a board‐certified small animal internist blindly reviewed transverse source CTEU and two, five, and 10 slab thick MIP images of 24 dogs enrolled in the study. Inclusion criteria included a diagnostic CTEU and either cystoscopic or surgical confirmation of the presence or absence of ureteral ectopia. Eleven dogs were confirmed to have 17 ectopic ureters at surgery and/or cystoscopically. There was no significant difference in reader diagnoses between viewing methods or between viewing methods and the surgical/cystoscopic findings (P < 0.001). Reader confidence was significantly greater on two (P = 0.0080) and five (P = 0.0009) slab thick MIP images with significant interobserver agreement between readers for all viewing methods (P values ranging between 0.0363 and <0.001). In addition, the diagnostic accuracy of MIP images was similar to or better than transverse source CTEU images, when assessed by a radiologist. The study results suggest that CTEU is a reliable imaging technique for diagnosing canine ectopic ureters among specialists of varied experience. In addition, thin slice reconstructed MIP images improve reader confidence and potentially diagnostic accuracy, and thus their use should be considered, especially in more challenging cases.     

COMPUTED TOMOGRAPHY ANGIOGRAPHY FOR EVALUATION OF PULMONARY EMBOLISM IN AN EXPERIMENTAL MODEL AND HEARTWORM INFESTED DOGS

This study was performed to characterize pulmonary embolism with computed tomography pulmonary angiography in experimental pulmonary embolism and heartworm infected dogs. In the experimental group, there were pulmonary changes after pulmonary embolism induction as follows: hypoattenuating round filling defects in pulmonary arteries, arterial dilations with straight and abrupt cut‐off appearances in the pulmonary embolism regions, pulmonary infarctions, a cavity formation and spontaneous pneumothorax, and emboli migration. In the heartworm‐infected group, three out of eight dogs developed pulmonary embolism, especially in the right caudal arteries. Arterial dilations with typical tortuosity were also identified, mainly in the right caudal arteries in five dogs. Computed tomography pulmonary angiography can be an important imaging modality in the diagnosis of pulmonary embolism and the evaluation of pulmonary arterial and parenchymal changes in dogs.     

ULTRASONOGRAPHIC MEASUREMENT OF KIDNEY-TO-AORTA RATIO AS A METHOD OF ESTIMATING RENAL SIZE IN DOGS

Renal size is an important parameter in the assessment of renal disease in dogs. However, because of the great variability in body conformation, absolute renal measurements cannot solely be used when evaluating kidneys with ultrasonography. The use of a ratio comparing renal length and aortic luminal diameter (K/Ao) was investigated. After confirming the reproducibility of these measurements, K/Ao ratios were obtained in 92 dogs without clinical evidence of renal disease. Left and right K/Ao ratios were statistically similar. Based on 95% confidence intervals, renal size should be considered reduced if the K/Ao ratio is < 5.5 and increased when > 9.1.