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.     

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 RADIOGRAPHY AND ULTRASONOGRAPHY FOR DIAGNOSING SMALL‐INTESTINAL MECHANICAL OBSTRUCTION IN VOMITING DOGS

A cross‐sectional study was performed on acutely vomiting dogs to compare the accuracy of radiography and ultrasonography for the diagnosis of small‐intestinal mechanical obstruction and to describe several radiographic and ultrasonographic signs to identify their contribution to the final diagnosis. The sample population consisted of 82 adult dogs and small‐intestinal obstruction by foreign body was confirmed in 27/82 (33%) dogs by surgery or necropsy. Radiography produced a definitive result (obstructed or not obstructed) in 58/82 (70%) of dogs; ultrasonography produced a definitive result in 80/82 (97%) of dogs. On radiographs, a diagnosis of obstruction was based on detection of segmental small‐intestinal dilatation, plication, or detection of a foreign body. Approximately 30% (8/27) of obstructed dogs did not have radiographic signs of segmental small‐intestinal dilatation, of which 50% (4/8) were due to linear foreign bodies. The ultrasonographic diagnosis of small‐intestinal obstruction was based on detection of an obstructive lesion, sonographic signs of plication or segmental, small‐intestinal dilatation. The ultrasonographic presence or absence of moderate‐to‐severe intestinal diameter enlargement (due to lumen dilatation) of the jejunum (>1.5 cm) was a useful discriminatory finding and, when present, should prompt a thorough search for a cause of small‐intestinal obstruction. In conclusion, both abdominal radiography and abdominal ultrasonography are accurate for diagnosing small‐intestinal obstruction in vomiting dogs and either may be used depending on availability and examiner choice. Abdominal ultrasonography had greater accuracy, fewer equivocal results and provided greater diagnostic confidence compared with radiography.     

DENTAL RADIOGRAPHY IN THE DOG WITH A CONVENTIONAL X-RAY DEVICE

This study describes a method of using a conventional x-ray device and film-positioning system for dental radiography in dogs. This system is economical, safe and results in high quality dental radiographs.     

A COMPARISON OF REAL-TIME ULTRASOUND, PALPATION AND RADIOGRAPHY IN PREGNANCY DETECTION AND LITTER SIZE DETERMINATION IN THE BITCH

Fifty-five bitches were examined once, at different intervals for pregnancy. Manual Papation, B-mode real-time ultrasoungraphy, and radiography were used to confirm pregnancy and to count the number of fetuses present. Predicted numbers were compared to whelping data obtained from owners. Radiography was confined to the last trimester of pregnancy and had an overall accuracy of 100% in pregnancy detection and 93% in correct litter size determination. A proor qualtiy radiograph contributed to the one incorrect count estimate. Ultrasound and palpation were used in all three trimester phases starting 3 weeks post coitus. For pregnancy detection ultrasound was 94% accurate (no false positives) and palpation was 88% accurate (one false positive). For fetal counting, ultrasound was 36% accurate and palpation was 12% accurate. Recommendations for the use of ultrasound and radiography in pregnancy evaluation are reviewed.     

ULTRASONOGRAPHIC FEATURES OF PERITONEAL CESTODIASIS CAUSED BY MESOCESTOIDES SP. IN A DOG AND IN A CAT

Peritoneal infections caused by Mesocestoides spp. are rare in dogs and cats. Little data exist on the role of abdominal ultrasonography for diagnosis and therapy management of the disease. We describe the ultrasonographic features of peritoneal cestodiasis in a dog and in a cat. In the dog, abdominal ultrasound allowed both a presumptive diagnosis and the collection of tissue samples to confirm peritoneal larval infection. Ultrasound was also very useful for therapy management. In the second patient the ultrasonographic features of tetrathyridial infection in a cat in which the parasite was observed as an incidental finding during ovariohysterectomy are described.     

TWO-DIMENSIONAL REAL-TIME OCULAR ULTRASONOGRAPHY IN THE DOG

Two-dimensional real-time ultrasonography was performed with three different methods to determine the optimal technique for scanning canine orbital soft tissues. The three techniques included positioning the transducer on the clipped closed eyelid (eyelid contact method), directly on the cornea (corneal contact method), or on a small waterfilled balloon in direct contact with the cornea (water bath offset method). Horizontal and vertical images from the three techniques were compared and graded for diagnostic quality. The corneal contact method provided superior anatomic definition of the posterior globe and extraorbital tissues, whereas the water bath method gave higher-quality images of the anterior chamber and lens. Use of the eyelid contact method to image the eye and periorbital structures was not recommended because of multiple artifacts that severely degrade the image.     

COMPARISON OF RADIOGRAPHY, MYELOGRAPHY AND COMPUTED TOMOGRAPHY FOR THE EVALUATION OF CANINE VERTEBRAL AND SPINAL CORD TUMORS IN SIXTEEN DOGS

Radiographic, myelographic and computed tomographic (CT) studies from sixteen dogs with histologically diagnosed vertebral or spinal cord neoplasia (seventeen lesions) were retrospectively evaluated. Radiographs were compared with CT images to evaluate vertebral bony changes (bone production, lysis or both). Myelographic and CT images were evaluated to separate lesions into one of three categories, extradural, intradural/extramedullary, or intramedullary. These findings were compared to histologic tumor type from surgical or necropsy samples. Histologically, seven lesions were vertebral tumors and were classified as extradural lesions; ten lesions were spinal cord tumors of which eight were classified as intradural/extramedullary and two as intramedullary. Using CT, the amount of bony change associated with extradural lesions was greater than or equal to the amount of bony change visualized using radiographs. Myelography more correctly differentiated between intradural/ extramedullary and intramedullary lesions than did CT, although three open diagnoses detracted from the CT results. This study suggests that when evaluating extradural lesions, the amount of bony change was better visualized using CT than survey radiographs. Myelography was better when compared to CT for classifying spinal cord lesions, however, standardization of the CT imaging protocol may help determine the specific clinical indications for using CT in dogs with suspected vertebral or spinal cord tumors.     

IMAGING DIAGNOSIS—DISSEMINATED PERITONEAL LEIOMYOMATOSIS IN A DOG

A 17‐month‐old male Labrador retriever presented for evaluation of an abdominal mass felt during abdominal palpation. Multiple variably sized cystic masses were identified on sonographic and radiographic images. Exploratory laparotomy revealed multiple peritoneal masses that exhibited atypical contractions and lacked an identifiable organ of origin. Histology and immunohistochemistry of multiple surgically excised masses was consistent with benign tumors of smooth muscle origin (leiomyomas). The presence of multiple peritoneal leiomyomas in this dog is consistent with disseminated peritoneal leiomyomatosis. Two years after diagnosis and multiple surgical interventions, continual insidious enlargement of leiomyomas was identified on ultrasound and CT.     

ENDOSCOPIC ULTRASONOGRAPHY OF THE PANCREAS IN THE DOG

Endoscopic ultrasonography was done in 12 normal adult dogs to investigate its efficacy in visualization of the pancreas. The endoscopic ultrasonographic device used in the present study had a curved-array ultrasound transducer mounted in front of the objective lens. The tip of the ultrasonic endoscope was inserted into the stomach, and all examinations of the pancreas were performed from within the stomach. Endoscopic ultrasonography provided good images of most parts of the pancreas except for the ends of each lobe. Useful information about the pancreatic parenchyma, including pancreatic lobular structure, pancreatic duct, and vessels of the pancreas was obtained by endoscopic ultrasonography. Blood flow within vessels was detected using color Doppler and pulsed-wave Doppler examination. These results suggest that endoscopic ultrasonography is available as an effective diagnostic modality in small animal practice.     

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.     

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.     

ADRENAL ULTRASONOGRAPHY IN THE DOG

The ultrasonographic appearance of the normal canine adrenal gland has not been described. This is due to the small size and shape of the canine adrenal glands, overlying abdominal viscera, similar acoustic texture to that of the surrounding tissue, frequent abundant perirenal fat, and the lack of patient compliance. Adrenal enlargement in association with hyperadrenocorticism, secondary to hyperplasia or neoplasia, can sometimes be identified by finding a distinct structure cranial and/or medial to the cranial pole of either kidney. Case history reports are used to characterize the appearance of adrenal enlargement from hyperplasia and adrenocortical adenocarcinoma. Additional case history reports are included to illustrate possible interpretation problems. Lack of ultrasonographic visualization of the adrenal gland does not rule out the possibility of enlargement, particularly if the enlargement in mild.     

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.     

RENAL AND HEPATIC ULTRASONOGRAPHY IN THE NEONATAL DOG

The ultrasonographic appearance and size of the liver and kidneys of a litter of five pups was examined from birth until six months of age, and compared with a group of five adults of the same breed. Increased renal cortical echogenicity was evident for the first two weeks of life. Up to 12 weeks of age renal size was relatively large in comparison with body size parameters. After 12 weeks measures of renal size were proportionate with body size and were not significantly different from adult dogs. The neonatal liver had a similar ultrasonographic appearance to the adult, although in the first eight weeks parenchymal echogenic stippling was less coarse and portal veins were less well delineated. Measures of hepatic length were inaccurate during the first four weeks after birth due to changes in body conformation. From eight weeks to six months of age these measures were proportionate with body size, although the ratios differed from adult dogs.     

TWO-DIMENSIONAL, REAL-TIME ECHOCARDIOGRAPHY IN THE DOG Technique and Anatomic Validation

Two-dimensional, real-time echocardiography (2DE), studied extensively in humans, has only recently been utilized in veterinary medicine. To develop standardized transducer locations and examination technique and to validate cardiac anatomy as imaged from these locations, 2DE was performed in 12 normal, anesthetized dogs. Anatomic structures were identified by shape, position and motion, selective microbubble-laden saline injections, and percutaneous pin insertion followed by necropsy dissection. Consistent echotomographic images were obtained from right intercostal and left intercostal transducer locations. From the right, long-axis and short-axis views of the heart were obtained. From the left, several long-axis views were possible. One or more views of all four cardiac chambers, atrioventricular and semilunar valves, and the proximal portions of the great vessels were obtained by systematic examination from both sides of the thorax. It was concluded that complete anatomic evaluation of the canine heart by 2DE was possible using a standardized, systematic examination technique.     

ENDOSCOPIC ULTRASONOGRAPHY FOR THE DIAGNOSIS OF INTRATHORACIC LESIONS IN TWO DOGS

Endoscopic ultrasound was developed initially in humans to overcome limitations of conventional ultrasound in examining certain internal organs due to intervening bone or air-filled structures. Endoscopic ultrasound has been used most widely in investigation of the gastrointestinal tract in humans, but many intrathoracic applications as well as endoscopic ultrasound-guided techniques have recently been described. Mediastinal and pulmonary structures can be examined with endoscopic ultrasound since a high frequency ultrasound probe can be brought into close contact with the areas of interest via a transesophageal approach. The purpose of this report is to describe the application of endoscopic ultrasound as an aid in the diagnosis of intrathoracic disease in the dog. Two dogs, one with a history of prior esophageal foreign body extraction, the other with apathy, weakness and dyspnea were referred for further investigation. Both dogs had caudal intrathoracic soft tissue opacities diagnosed radiographically, but their origin and nature were difficult to determine. Conventional ultrasound was limiting in both dogs due to their location and superimposition of gas-filled structures. With endosonography lesions were characterized more completely. We have found endoscopic ultrasound to be an elegant diagnostic tool for the investigation of radiographically detected intrathoracic lesions in the dog whose origins are difficult to determine or do not lend themselves to investigation by conventional ultrasound. Endoscopic ultrasound provides valuable diagnostic information complementary to that provided radiographically which aids in therapeutic planning. Endoscopic ultrasound was also more sensitive for detecting mediastinal lymphadenomegaly than radiography in one of the dogs. An additional advantage of endoscopic ultrasound is the fact that US-guided tissue sampling can be performed during the examination.     

COMPARISON OF COMPUTED RADIOGRAPHY AND CONVENTIONAL FILM-SCREEN RADIOGRAPHY OF THE EQUINE STIFLE

Major advantages of computed radiography are the potential reduction of dose and the possibility of postprocessing. In our study, we compared conventional radiographs to digital radiographs of the equine stifle by subjective evaluation of diagnostic quality when using a decreasing photon flux (mAs). Twelve equine stifle joints from horses of different weight and size were examined. Conventional and digital radiographs were performed identically in a caudocranial projection with the tube angled 15 degrees. A series of four radiographs was performed in each technique with an increasing photon flux starting with 2.5 mAs and going up to 5, 10, and 20 mAs. All radiographs were evaluated subjectively in a blinded fashion by seven readers in terms of contrast, bone structure, and diagnostic value and were graded using a 1-5 scale. Results from conventional and digitized radiographs were compared, and differences between the individual observers were analyzed statistically. Contrast, bone structure, and diagnostic value from digital images were rated significantly better than from conventional images (p < .001). For both techniques, a decrease in ranking was found with a decrease of photon flux. There was only slight interobserver variability. A dose reduction up to a factor of 4 compared to a 100 speed film-screen system seems to be possible without loss of information. Weight and size of the horse are not major influences.     

SONOGRAPHIC AND RADIOGRAPHIC CHANGES ASSOCIATED WITH SPLENIC TORSION IN THE DOG

The clinical, radiographic, and sonographic signs in three dogs with splenic torsion are presented. AH dogs exhibited weight loss, anorexia, and lethargy. Splenomegaly was consistent radiographic finding in two dogs and large ill-defined midabdominal mass was seen in one dog. The spleen was easily imaged sonographically in all dogs. Splenic sonography in two dogs showed diffuse, hypoechoic pattern consistent with splenic congestion. Hilar splenic vessels were enlarged on the sonograms of two dogs.