ULTRASONOGRAPHIC DIAGNOSIS OF GASTROINTESTINAL SMOOTH MUSCLE TUMORS IN THE DOG

Historical, physical examination, clinicopathologic, radiographic and ultrasonographic findings of 13 dogs with gastrointestinal (GI) smooth muscle tumors (11 leiomyosarcomas, 2 leiomyomas) were reviewed. History, including signalment and chief complaint, physical examination and bloodwork were neither sensitive nor specific for GI neoplasia. Imaging procedures, radiology and ultrasonography, detected the presence of abdominal masses in 12 patients, including 9 animals lacking a palpable mass on initial examination. Survey radiographs of 10 of the 13 dogs revealed a mass effect in 5/10 dogs, evidence of peritoneal effusion or free abdominal gas in 3/10 dogs, and an obstructive pattern with gas and fluid distension of the intestinal tract in 1/10 dogs. Ultrasonography identified an abdominal mass in 12/13 dogs, and peritoneal effusion in 5 animals. Ultrasonography correctly recognized an association of the mass with bowel segments by the presence of intraluminal gas, within or adjacent to the mass effect, in 10 dogs, and strongly suggested an intestinal origin in one additional animal. GI smooth muscle tumors often appeared as large masses, eccentrically projecting from the bowel wall, frequently containing single or multiple hypo/anechoic regions. Based on this study we conclude that ultrasonography is more sensitive than survey radiography in the detection of GI smooth muscle tumors, and may present specific features to distinguish smooth muscle tumors from other types of GI tumors. Ultrasonography is recommended as a screening procedure for cases where GI neoplasia is suspected.     

SURVEY OF THE USE OF RADIOGRAPHY VS. ULTRASONOGRAPHY IN THE INVESTIGATION OF GASTROINTESTINAL FOREIGN BODIES IN SMALL ANIMALS

A question frequently asked by clinicians who are treating small animals suspected of having gastrointestinal foreign bodies is whether one imaging test such as survey radiography or ultrasonography is sufficient to make the diagnosis. A study was undertaken to try and answer this question. Survey abdominal radiography and ultrasonography was performed on 16 small animals (11 dogs, five cats) with clinical signs of an obstruction because of a confirmed gastrointestinal foreign body. The majority of the foreign bodies (14/16) were confirmed by surgical removal and were located in the small intestine. A gastric foreign body was retrieved endoscopically and a colonic foreign body was passed in the feces. Radiographically identifiable foreign bodies were evident in nine animals. Small intestinal overdistension was present radiographically in seven animals. Ultrasonography detected a foreign body in all 16 animals. The foreign bodies were identified by their distal acoustic shadowing and variable degrees of surface reflection. An intestinal perforation was detected sonographically but not radiographically. The value of additional sonographic findings including thickening of the gastrointestinal wall and loss of layering, free peritoneal fluid, and lymphadenopathy in these animals is discussed. The findings in this series suggest that in a small animal with a gastrointestinal foreign body, ultrasonography alone could be used to make the diagnosis and may be a more appropriate choice than survey radiography.     

Comparison of computed radiography and conventional radiography in detection of small volume pneumoperitoneum

The role of digital imaging is increasing as these systems are becoming more affordable and accessible. Advantages of computed radiography compared with conventional film/screen combinations include improved contrast resolution and postprocessing capabilities. Computed radiography's spatial resolution is inferior to conventional radiography; however, this limitation is considered clinically insignificant. This study prospectively compared digital imaging and conventional radiography in detecting small volume pneumoperitoneum. Twenty cadaver dogs (15-30 kg) were injected with 0.25, 0.25, and 0.5 ml for 1 ml total of air intra-abdominally, and radiographed sequentially using computed and conventional radiographic technologies. Three radiologists independently evaluated the images, and receiver operating curve (ROC) analysis compared the two imaging modalities. There was no statistical difference between computed and conventional radiography in detecting free abdominal air, but overall computed radiography was relatively more sensitive based on ROC analysis. Computed radiographic images consistently and significantly demonstrated a minimal amount of 0.5 ml of free air based on ROC analysis. However, no minimal air amount was consistently or significantly detected with conventional film. Readers were more likely to detect free air on lateral computed images than the other projections, with no significant increased sensitivity between film/screen projections. Further studies are indicated to determine the differences or lack thereof between various digital imaging systems and conventional film/screen systems.     

COMPARISON OF THORACIC ULTRASONOGRAPHY AND RADIOGRAPHY FOR THE DETECTION OF INDUCED SMALL VOLUME PNEUMOTHORAX IN THE HORSE

Small volume pneumothorax can be challenging to diagnose in horses. The current standard method for diagnosis is standing thoracic radiography. We hypothesized that thoracic ultrasonography would be more sensitive. Objectives of this prospective, experimental study were to describe a thoracic ultrasound method for detection of small volume pneumothorax in horses and to compare results of radiography and ultrasound in a sample of horses with induced small volume pneumothorax. Six mature healthy horses were recruited for this study. For each horse, five 50 ml air boluses were sequentially introduced via a teat cannula into the pleural space. Lateral thoracic radiographs and standardized ultrasound (2D and M‐mode) examinations of both hemithoraces were performed following administration of each 50 ml air bolus. Radiographs and ultrasound images/videos were analyzed for detection of pneumothorax by four independent investigators who were unaware of treatment status. Sensitivity, specificity, positive predictive values, negative predictive values, and agreement among investigators (Kappa test, κ) were calculated for radiography, 2D and M‐mode ultrasound. Comparisons were made using a chi‐squared exact test with significance set at P < 0.05. Two‐dimensional (84%) and M‐mode (80%) ultrasound were more sensitive than radiography (48%) for pneumothorax detection (P = 0.02 and P = 0.04, respectively). Specificity and positive predictive values were similar for all three imaging modalities (P = 1). Agreement between investigators for pneumothorax detection was excellent for 2D ultrasound (κ = 1), very good for M‐mode ultrasound (κ = 0.87), and good for radiography (κ = 0.79). Findings from this experimental study supported the use of thoracic ultrasonography as a diagnostic method for detecting pneumothorax in horses.     

Sonographic detection of small amounts of free peritoneal gas in beagle dogs

The detection of small amounts of free peritoneal gas in the canine patient can pose a diagnostic dilemma. The objective of this study was to determine how much of this free gas could be detected ultrasonographically. Ultrasound examinations were carried out after increments (0.1 ml) of air were intraperitoneally injected. Via ultrasonography, 0.4 ml of free gas can be reliably detected. The authors concluded that ultrasonography is a very sensitive modality for the detection of small amounts of peritoneal free gas (above 0.4 ml).     

ULTRASONOGRAPHY AND RADIOGRAPHY OF THE CANINE POSTPARTUM UTERUS

A vulvovaginal discharge following parturition in a bitch is often a cause of concern to owners and clinicians, especially if whelping was complicated in any way. Ultrasonography could potentially distinguish between normal and abnormal postpartum uterine states because the uterine wall and luminal contents can be imaged in detail. Five normal bitches were examined to determine the normal ultrasonographic appearance of the postpartum uterus and the sensitivity of ultrasonography in detecting the involuting uterus, comparing this sensitivity with that of radiography. Ultrasonography was done at 1, 4, 8, 12, 18 and 24 days postpartum, radiography at 1, 4, 8, 12 and 18 days postpartum. By 12 days postpartum, the uterus could not be seen on radiographs, while at 24 days postpartum the uterus was still sonographically identifiable. The ultrasonographic characteristics of the involuting uterus are described.     

Comparison of thoracic radiographs and single breath-hold helical CT for detection of pulmonary nodules in dogs with metastatic neoplasia

Imaging studies in people indicate that x-ray computed tomography (CT) is a more sensitive technique than thoracic radiography for the detection of pulmonary metastasic neoplasia. Systematic studies comparing CT and thoracic radiographic techniques in veterinary patients have not been performed. The present retrospective study was designed to directly compare the efficacy of these 2 techniques in detecting pulmonary nodules in dogs. Eighteen dogs with histologically confirmed pulmonary metastatic neoplasia had contemporaneous thoracic radiographs and pulmonary CT scans compared. Quantitative analyses included estimation of pulmonary nodule size, number, and lobar distribution on thoracic radiographs and CT images. Only 9% of CT-detected pulmonary nodules were identified on thoracic radiographs (P < .003). The lower size threshold was approximately 1 mm to detect pulmonary nodules on CT images and 7-9 mm to reliably detect nodules on radiographs (P < .0001). Additionally, pulmonary nodules were detected in a significantly greater number of lung lobes using CT as compared with thoracic radiographs (P < .0001). These data indicate that CT is significantly more sensitive than thoracic radiography for detecting soft-tissue nodules in dogs. As such, thoracic CT should be considered in any patient with neoplasia that has potential for pulmonary metastasis to more reliably stage the disease, particularly when accurate characterization of the extent and distribution of pulmonary metastatic disease affects therapeutic planning.     

RADIOGRAPHIC AND COMPUTED TOMOGRAPHIC EVALUATION OF OTITIS MEDIA IN THE DOG

The purpose of this study was to compare computed tomography (CT) and radiography in the identification of canine middle ear disease. Fourteen canine patients underwent a radiographic "bullae series" and CT examination of the tympanic bullae. Confirmation of otitis media was based on surgery. The overall diagnostic accuracy of CT and radiographs regarding the diagnosis of otitis media was similar. Although a marked difference was not detected between radiographs and CT for detecting otitis media using Youden's index values, CT was a more sensitive test for the detection of otitis media.     

ULTRASONOGRAPHY VERSUS RADIOGRAPHY FOR DETECTION OF FLUID IN THE CANINE TYMPANIC BULLA

The tympanic bullae of 20 previously healthy cadaver animals were randomly filled with sterile saline or air. The heads were positioned using tape ties and a rostrocaudal open mouth radiograph taken. The resulting radiographs were assessed by a blinded ECVDI diplomate, with each tympanic bulla being recorded as being either air or fluid filled. Ultrasound examination of the bullae was performed, by a blinded assessor, using a B-mode 5 mHz sector probe (Sonotron-VingMed Sound A/S, PO Box 141, N3191, Horten, Norway) operating at 3 mHz. Each bulla was recorded as being either air or fluid filled. Results of radiography and ultrasonography were each compared to the actual status of the bulla in a chi square analysis. Sensitivity of radiography was 80%, with specificity of 65%. Ultrasonographic sensitivity was 100% and specificity 100%. Ultrasonography may in future provide a cheap, noninvasive, rapid and widely available method for diagnosing otitis media in clinical cases.     

COMPARISON OF COMPUTED TOMOGRAPHY AND ABDOMINAL RADIOGRAPHY FOR DETECTION OF CANINE MECHANICAL INTESTINAL OBSTRUCTION

Vomiting, often caused by mechanical intestinal obstruction, is common in dogs. Equivocal radiographic signs often necessitate repeat radiographs or additional imaging procedures. For our prospective, case‐controlled, accuracy study, we hypothesized the following: (1) using computed tomography (CT), radiologists will be more sensitive and specific for detecting mechanical intestinal obstruction and recommending surgery compared to using radiographs; and (2) using measurements, radiologists will be more sensitive and specific using radiographs or CT for detecting mechanical intestinal obstruction and recommending surgery. Twenty dogs had abdominal radiographs and abdominal CT. Seventeen dogs had abdominal surgery and three dogs were not obstructed based on clinical follow‐up. Confidence levels (five‐point scale) of three experienced radiologists for mechanical intestinal obstruction and recommending surgery were recorded before and after making selected measurements. Eight dogs had surgically confirmed mechanical intestinal obstruction, and 12 dogs did not have obstruction. For detecting mechanical intestinal obstruction, CT was more sensitive (95.8% vs. 79.2%) and specific (80.6% vs. 69.4%) compared to radiographs, but the difference was not statistically significant. For recommending surgery, radiography was more sensitive (91.7% vs. 83.3%) and specific (83.3% vs. 72.2%) than using CT, but differences were not statistically significant. We reported objective CT measurements for predicting small mechanical intestinal obstruction. By incorporating these objective data, the diagnosis of mechanical intestinal obstruction changed in five of 120 instances (radiographs and CT). In no instance (0/120), did the objective data change the recommendation for surgery. Using CT or abdominal radiographs for the detection of canine mechanical intestinal obstruction is sensitive and specific when evaluated by experienced veterinary radiologists.     

Detection of rib trauma in newborn foals in an equine critical care unit: a comparison of ultrasonography, radiography and physical examination

REASONS FOR PERFORMING STUDY: Previous studies have shown that in man ultrasonography is more accurate than radiography for detecting rib fractures. OBJECTIVES: To describe clinical, radiographic and ultrasonographic findings related with rib fractures in newborn foals in an equine critical care unit; and to compare diagnostic accuracy of ultrasonography to radiography. METHODS: A prospective ultrasonographic study was performed on 29 foals presented to the emergency unit. This study was performed at the Centre Hospitalier Universitaire Vétérinaire (CHUV), University of Montreal. Physical examination as well as radiographic and ultrasonographic examinations were performed. RESULTS: Thoracic radiographs revealed 10 rib fractures in 5 of 26 (19%) foals. Ultrasonography revealed 49 fractures in 19 of 29 (65%) foals of which fillies (n = 13; 68%) were significantly over represented as were fractures to the left thorax (n = 15; 78%). Seventeen of 19 foals (90%) had rib fractures located 3 cm or less from the costochondral junction, the distal part of the rib being displaced laterally in all cases. In 2 foals, where both thoracic radiographs and ultrasonography detected rib fractures, the site of fractures was located on the mid portion of the rib. Rib fractures were detected only by thoracic radiographs in one foal. Sixty-five percent (32/49) of fractured ribs had a moderate displacement (1-4 mm). CONCLUSIONS: Rib fractures are seen frequently in newborn foals in equine critical care units. Ultrasonography is more accurate than radiography and reveals fractures in most patients presented in emergency. The position (costochondral junction) of rib fractures and of the fragments suggest that most thoracic trauma probably occurs during parturition. POTENTIAL RELEVANCE: Ultrasound imaging increases awareness and improves the diagnosis of rib fractures in newborn foals.     

RADIOGRAPHIC AND ULTRASONOGRAPHIC FINDINGS OF EMPHYSEMATOUS CYSTITIS IN FOUR NONDIABETIC FEMALE DOGS

The urinary bladder of four dogs with emphysematous cystitis was assessed radiographically. Ultrasonography was also performed using a 7.5-MHz microconvex probe in dorsal recumbency and in a standing position. Ultrasonographically there were bright echoes and reverberations typical of gas in all dogs. This was entrapped in the bladder wall as it appeared in the same location in recumbent and standing positions. Bladder size was reduced and bladder content was echogenic in all dogs. In only one out of the four dogs was a gas stripe seen in the bladder on radiographs. Proteus mirabilis was isolated from the urine of all patients. Diabetes was ruled out on the basis of urine and blood analysis. A small amount of gas can be difficult to detect on radiographs. Ultrasonography appears to be a more sensitive technique for detection of gas within the bladder at an early stage of emphysematous cystitis. Prevalence of emphysematous cystitis may be underestimated if only radiographs are made.     

Comparison of radiography and ultrasonography to detect osteochondrosis lesions in the tarsocrural joint: A prospective study

Reasons for performing study: Lesions located on the medial malleolus of the tarsocrural joint can be difficult to image radiographically. Ultrasonography allows evaluation of articular cartilage and subchondral bone. Objectives: To compare dorso30° lateral‐plantaromedial‐oblique (DL‐PlMO) and dorso45° views to detect lesions on the medial malleolus, to validate the use of ultrasonography to show lesions in the tarsocrural joint and to compare its sensitivity to radiography. Methods: Tarsocrural joints (n = 111) with osteochondrosis were evaluated ultrasonographically and radiographically prior to arthroscopic lesion debridement. A complete radiographic examination was made and the best view to detect each lesion recorded. Longitudinal and transverse ultrasonography of the dorsal aspect of the joint was performed and the best scan plane to image each lesion recorded. Results: There were 94 joints with lesions on the distal intermediate ridge of tibia, 24 with lesions on the medial malleolus, and 4 with lesions on the lateral trochlear ridge. The sensitivity of radiography to detect lesions on the medial malleolus and distal intermediate ridge of tibia was 71 and 96%, respectively. Eighty‐two percent of lesions on the medial malleolus were better imaged on dorso30° view. The sensitivity of ultrasonography to detect lesions on the medial malleolus and distal intermediate ridge of tibia was 83 and 98%, respectively. Ultrasonography was significantly more sensitive than radiography to detect lesions on the medial malleolus and distal intermediate ridge of tibia. Conclusion: Dorso30° lateral‐plantaromedial‐oblique view was the best to image lesions on the medial malleolus. Ultrasonography was a valuable diagnostic tool to diagnose lesions in the tarsocrural joint and was more sensitive than radiography for lesions located on the medial malleolus and distal intermediate ridge of tibia. Clinical relevance: Radiographic examination should include a dorso30° view for detection of lesions on the medial malleolus and ultrasonography should be considered to diagnose osteochondrosis in the tarsocrural joints.     

Comparison between diagnostic ultrasonography and radiography in the evaluation of horses and cattle with thoracic disease: 56 cases (1984-1985)

The results of radiography and ultrasonography were compared on 56 horses and cows with lower respiratory tract disease. Ultrasonography was more sensitive than radiography for the detection of small pleural effusions and consolidations in large animals. The side of the thorax affected and the character of the pleural fluid and lung in large animals with pleural effusion can be evaluated ultrasonographically. The periphery of the lung must be affected to characterize pulmonary lesions ultrasonographically. Radiography is the best technique to characterize lesions deep within the lung when the periphery of the lung is normal.     

RADIOGRAPHIC CHARACTERIZATION OF THE OS PENIS IN THE CAT

The os penis in the cat has not been described radiographically, as compared with the dog. However, a small linear bony radiopacity is sometimes detected in the perineal area of male cats. We hypothesized that the feline os penis might be visible on survey radiographs of the pelvis, and we aimed to investigate the frequency of its visualization using analog and computed radiography (CR) system. One hundred radiographs of the pelvis of 99 male cats were reviewed retrospectively (50 were obtained with a CR system and 50 with an analog system). Age, breed, neutering status, and reason for presentation were recorded, as well as the visualization of the os penis. An os penis was detected in 19/50 (38%) cats with CR and in eight of 50 (16%) cats with analog radiography; this difference was statistically significant. With CR, the median age of cats with a visible os penis was significantly higher than in cats where the os penis was not seen. In one cat with a visible os penis examined with CR and analog radiography, the os penis was only visible on CR images. The penile tissues were examined histopathologically in one cat and well‐differentiated bone was found but there were no pathologic findings detected in surrounding tissues. Thus, the os penis can be detected on radiographs of cats and this should not be mistaken for a pathologic finding such as urolithiasis or dystrophic mineralization.     

COMPARATIVE PERFORMANCE OF RADIOGRAPHY AND COMPUTED TOMOGRAPHY IN THE DIAGNOSIS OF MIDDLE EAR DISEASE IN 31 DOGS

The purpose of this study was to compare computed tomography (CT) and radiography for diagnosing the presence and severity of middle ear disease in dogs with a history of chronic otitis externa. Thirty-one dogs undergoing a total ear canal ablation and bulla osteotomy were studied. Three normal dogs served as controls. All dogs were examined using radiography and CT. Three radiologists independently evaluated imaging studies in random order. A visual analog scale method was used for scoring certainty and severity of middle ear disease. Surgical findings were recorded intra-operatively. Bulla lining samples were submitted for histopathologic evaluation and scored by a single pathologist who also used a visual analog scale system. Findings from both imaging modalities agreed more closely with surgical findings than with histopathologic findings. With either surgical or histopathologic findings as the gold standard, CT was more sensitive than and as specific as radiographs for predicting presence and severity of middle ear disease. Observer performance with CT was more consistent than the performance with radiographs in the detection of changes that occur with middle ear disease. Both radiography and CT were more accurate for predicting the severity of the disease than its presence. Findings indicate that CT is more accurate and reliable than radiography in diagnosing middle ear disease for dogs having concurrent otitis externa, but only when severity of disease is moderate or high. With low severity of disease, diagnostic certainty for both modalities becomes more variable.     

Comparison of radiography and ultrasonography in the evaluation of renal lesions in the dog

Survey abdominal radiographs, excretory urograms, and nephrosonograms were obtained from 14 dogs with renal lesions. Renal enlargement was suspected on survey radiographs and confirmed by excretory urography in 13 dogs. Radiographic differentiation between a solid and cystic renal lesion was not possible in 9 dogs. Ultrasonography determined the presence of solid masses in 12 dogs, established the presence of a renal cyst in the opposite kidney in 1 dog, and revealed hydronephrosis in 2 dogs. Ultrasonography appeared to be more sensitive than radiography in differentiating the internal characteristics of renal lesions.     

RADIOGRAPHIC EVALUATION OF INDUCED PNEUMOTHORAX IN THE DOG

Serial radiographic examinations were used to assess the incidence of bilateral and unilateral pneumothorax and its resolution following the introduction of air into a pleural space in each of 24 adult mix-breed dogs. Twenty-two (92%) dogs developed bilateral pneumothorax and two dogs (8%) developed unilateral pneumothorax. Volumes of air equal to 5 ml/kg, 15 ml/kg, and 45 ml/kg of body weight had resolved in all dogs developing bilateral pneumothorax by 7, 10, and 14 days, respectively. The vertical beam left lateral recumhent and the expiratory horizontal beam ventrodorsal views were the most effective radiographic views for the detection of pneumothorax. Separation of the visceral and parietal pleural surfaces on the horizontal beam ventrodorsal view was a better indication of small amounts of air in the pleural spaces than separation of the heart from the sternum on the vertical beam lateral view. The right lateral recumbent view, regardless of heam orientation, was most sensitive for the detection of differences in the amount of air in the pleural spaces.     

COMPARISON OF DIGITAL RADIOGRAPHY,ULTRASONOGRAPHY, AND POSITIVE CONTRAST VAGINOURETHROGRAPHY FOR DETERMINING REPRODUCTIVE STATUS OF FEMALE CATS

It is not always possible to identify female cats that have undergone previous ovariohysterectomy based on physical examination alone. An easy, cost‐effective method for screening female cats for reproductive status would be helpful for avoiding unnecessary exploratory laparotomies. The purpose of this prospective study was to compare diagnostic sensitivities of digital radiography, ultrasonography, and positive contrast vaginourethrography for determining reproductive status in female cats. Sixty‐seven recently euthanized female cats of unknown medical history and reproductive status were randomly selected and included in the study. Digital abdominal radiography, digital abdominal radiography with compression, abdominal ultrasonography, and positive contrast vaginourethrography were performed in sequence by a board‐certified veterinary radiologist and a second‐year radiology resident. Immediately following diagnostic imaging procedures, necropsy was performed. Ultrasonography of the uterus had the highest sensitivity (86%) for determining reproductive status of all the imaging modalities tested. The specificity was 88%, and the positive predictive value and negative predictive value were 96% and 68%, respectively. The calculated sensitivities and specificities of other modalities were as follows: digital radiographs (28%, 100%), digital compression radiographs (58%, 100%), and vaginourethrography (32%, 100%). Based on McNemar's test statistic, there was a significant difference in the sensitivity of ultrasound compared to digital radiographs (P ≤ 0.05), compression radiographs (P ≤ 0.05), and vaginourethrogram (P ≤ 0.05). Findings from the current study indicated that ultrasonography is a sensitive diagnostic test for determining reproductive status in female cats. Although more readily available in private practice and shelters, digital radiography and vaginourethrography are not reliable predictors of reproductive status.     

The left lateral projection is comparable to horizontal beam radiography for identifying experimental small volume pneumoperitoneum in the canine abdomen

Nontraumatic spontaneous pneumoperitoneum suggests the presence of gastrointestinal perforation; early detection can be lifesaving. Horizontal beam projections have been reported to be more sensitive than standard radiographic views for detecting small volumes of free peritoneal gas. This prospective, experimental, analytical study compared both left lateral (LL) and ventrodorsal (VD) standard views to horizontal beam projections for detecting small volumes of artificially induced pneumoperitoneum in live dogs. The effect of radiology training on accurate detection of small amounts of free peritoneal air was also assessed. Fourteen dogs had four radiographic projections taken after injection of 0, 2.5, 5, and 10 mL of cumulative air into their abdominal cavities. Radiographs were interpreted individually by three American College of Veterinary Radiology‐certified radiologists and three small animal internship‐trained veterinarians who were blinded to the air volume injected. At 2.5 and 10 mL of air injected, the LL projection had highest odds of an accurate response (odds ratio [OR] = 2.4 and 99.0 when compared to VD horizontal and VD projections, respectively). At 5 mL of air injected, the lateral horizontal (LH) projection had the highest odds of an accurate response (OR = 3.2 compared to VD horizontal). The LL projection was not significantly different from the LH projection at all volumes of air injected. Board certification led to higher odds of accurate responses at volumes of 5 (OR = 2.2) and 10 mL (OR = 3.6), as compared to nonspecialist veterinarians. Overall, LH and standard LL appeared to be the most useful radiographic projections for detection of small amounts of free peritoneal gas.