ULTRASONOGRAPHIC IMAGING OF THE LATERAL CEREBRAL VENTRICLES IN THE DOG

Ultrasonography was effectively used to evaluate lateral cerebral ventricles in 28 dogs with persistent fontanelles. There was a significant incidence of ventriculomegaly in miniature and brachycephalic breeds. No relationship was found between the size and the fontanelle and the presence or size of ventriculomegaly. A significant relationship was found between the presence of a fontanelle and the presence of ventriculomegaly. There was no statistically significant relationship found between the presence of clinical signs and ventricular size.     

ULTRASONOGRAPHIC FEATURES OF CANINE LIPOMAS

The purpose of this study was to evaluate the ultrasonographic features of canine lipomas. A group of 94 dogs with a soft tissue mass was considered. All dogs were examined ultrasonographically and cyto/histologic examination was performed. Twenty-four dogs, whose mass was diagnosed as a lipoma, were selected. Fifty-five lipomas were present on the 24 dogs. Fifty-one lipomas were superficial and located subcutaneously. Four lipomas were deep and located in the paratesticular region. Ultrasonographically, lipomas appeared as oval, well-defined, encapsulated, striated masses.     

ULTRASONOGRAPHIC ANATOMY OF THE CANINE ELBOW

To produce detailed ultrasonographic images of the soft tissue structures around the canine elbow joint, a series of greyhound cadaver limbs were scanned both intact and dissected in a water bath. Suitable transducer positions and bone landmarks are described and the ultrasonographic appearance of the lateral collateral ligament, anconeal process, triceps tendon, origin of olecranon ligament, biceps tendon insertion, medial collateral ligament, and medial coronoid process are illustrated. Improved understanding of the anatomy of the canine elbow will support clinical ultrasonography of this region.     

ULTRASONOGRAPHIC FEATURES OF CANINE GASTROINTESTINAL PYTHIOSIS

Pythiosis is a chronic pyogranulomatous infection of the gastrointestinal tract or skin caused by the water borne pathogen Pythium insidiosum. The ultrasonographic features of nine dogs with gastrointestinal pythiosis are reported. The stomach, duodenum, jejunum or colon were affected. All dogs had thickening of the gastrointestinal wall and areas with obliteration of the normal layered appearance. In one dog an eccentric mass was found arising from the serosal surface of the wall of the colon with mild diffuse wall thickening. Regional lymph node enlargement was seen in seven of the nine dogs. One dog had invasion of the pancreas and signs compatible with extrahepatic biliary obstruction. When compared to previous reports of gastrointestinal neoplasia, the features of wall thickening, loss of layering and regional lymphadenopathy are not considered specific for gastrointestinal pythiosis. Histological examination of tissue specimens is required for diagnosis.     

ULTRASONOGRAPHIC ANATOMY OF THE NORMAL CANINE KIDNEY*

Radiographic and ultrasonic examinations were performed in 12 normal dogs. Initial ultrasound examinations were performed in normally hydrated dogs. The ultrasonic appearance of the diuresed kidney was evaluated after excretory urography and intramuscular administration of furosemide. The dogs were euthanized for anatomic correlation with the sonographic appearance of the kidneys. Renal cortex, medulla, pelvic diverticula, intrarenal vessels, renal pelvis, and renal sinus fat were identified sonographically. Kidney enlargement during diuresis was due to increase renal medullary size. Veterinary Radiology, Vol. 25, No. 4, 1984; pp 173–178.     

ULTRASONOGRAPHIC DESCRIPTION OF CANINE MASTITIS

Ultrasonographic images were acquired of the mammary glands of 40 bitches with physiologically lactating (n = 20) or inflamed glands (n = 20). Echogenicity, structure, homogeneity, thickness, and distinguishability of each tissue layer were assessed. Additionally, overall echogenicity was noted. In the normal lactating gland, different tissues could be differentiated easily. The parenchyma was, without exception, separated from adjacent tissues and was visible as medium echogenic tissue with a coarse-grained structure. The tissue always had some echogenic lines and anechoic areas and was slightly heterogeneous. The loss of distinct layering of the tissue was characteristic of an inflamed mammary gland and inflamed regions had reduced echogenicity. Additionally in five bitches with mastitis, the ultrasound examination was repeated five times for documentation of the progress of the illness and associated changes, supplemented with a color Doppler sonogram to assess changes in blood vessel density. Information from the examinations carried out via B-mode did not allow treatment success to be predicted. Two bitches with reduced blood vessel density centrally had a poor outcome whereas three bitches with increased blood vessel density had a good outcome. Thus, Doppler sonography might be a useful tool to obtain information of the prognosis in acute canine mastitis.     

ULTRASONOGRAPHIC ANATOMY OF THE NORMAL CANINE CALCANEAL TENDON

To provide a series of detailed ultrasonographic images of the canine calcaneal tendon, greyhound cadaver pelvic limbs were scanned with a high-resolution transducer, and images compared with dissected specimens. The three components of the calcaneal tendon are the tendons of insertion of the gastrocnemius, superficial digital flexor, and a conjoined tendon formed by tendons from the biceps femoris, semitendinosus, and gracilis. Each of these three tendons was visible in transverse ultrasound images, each measuring 2.4-3.2-mm thick at mid-calcaneal tendon. Improved understanding of the anatomy of the calcaneal tendon will support clinical ultrasonography of this region.     

ULTRASONOGRAPHIC ASSESSMENT OF THE CANINE SCIATIC NERVE

To describe the ultrasonographic technique for investigation of the canine sciatic nerve, four canine cadaver pelvic limbs, two live healthy dogs, and five canine patients with suspected peripheral sciatic nerve lesions were examined with a high-resolution linear ultrasound transducer. The caudal part of the lumbosacral trunk and the origin of the sciatic nerve were visualized through the greater ischiatic foramen. The two components of the sciatic nerve, common peroneal and tibial nerves, were distinguished along the entire length of the nerve, until they branched at the level of the distal femur. In healthy live dogs they appeared as two adjacent hypoechoic tubular structures with internal echotexture of discontinuous hyperechoic bands, surrounded by a thin rim of highly echogenic tissue. The common peroneal component had a smaller diameter and was on the cranial aspect of the tibial component. An ultrasonographic lesion compatible with a peripheral nerve sheath tumor was found in one dog. Improved understanding of the ultrasonographic anatomy of the sciatic nerve supports clinical use of this modality.     

ULTRASONOGRAPHIC PARAMETERS OF NORMAL CANINE ADRENAL GLANDS: COMPARISON TO NECROPSY FINDINGS

Ultrasonographic evaluation of the adrenal glands was performed in 14 fasted healthy adult dogs. Frequency of visualization was 100% for both the left and right adrenal glands. Moderate correlation was present between Ultrasonographic and gross measurements of thickness for both left (r_s= 0.727; p < .005) and right (r_s= 0.537; p < .05) adrenal glands. However, no correlation was found between Ultrasonographic and gross measurements for length or width of either adrenal gland. Differentiation of adrenal cortex and medulla was possible in 79% of left adrenal glands and 64% of right adrenal glands. The echogenicity of the adrenal glands was less than that of the renal cortex in all dogs. Factors which made evaluation of the adrenal glands more difficult included pyloric gas, intestinal gas, and deep-chested body conformation.     

COMPARISON OF ULTRASONOGRAPHIC AND RADIOGRAPHIC MEASUREMENTS OF CANINE PROSTATE DIMENSIONS

The purposes of this study were to: 1) compare prostatic dimensions measured on radiographic and ultrasonographic images and 2) compare a subjective radiographic assessment of prostate size with a previously-described objective method. Thirty-four male dogs undergoing investigation of prostatic disorders were used. Prostate length and depth were measured from ultrasonographic and radiographic images. A subjective assessment of prostate size ('small', 'normal', or 'enlarged') was made in 29 animals by one of the authors who was unaware of radiographic or ultrasonographic measurements. In addition, the distance from sacral promontory to the pubic brim was also measured. A prostate length or depth of >70% of this distance was defined as 'enlarged' and <70% as 'normal'. After the effects of magnification on radiographic measurements were eliminated, there were no significant differences between prostatic length measured by the two methods. However, a significant difference was obtained between prostatic depth measurements. The subjective assessment agreed with a previously described objective assessment of prostatic size in 21/29 dogs for prostate length but in only 12/29 for depth. Prostatic length varied from 46.6 to 116.4% (mean 75.7%) of the distance from the pubic brim to the sacral promontory. Prostatic depth varied from 33.0% to 94.6% (mean 59.7%) of the same distance. It is recommended that prostate length, rather than depth, be used when evaluating prostate size from lateral abdominal radiographs.     

ULTRASONOGRAPHIC EVALUATION OF THE CANINE SHOULDER

The aim of this study was to determine the normal ultrasonographic anatomy of the canine shoulder. Fourteen shoulders from 7 clinically normal mid-sized dogs were radiographed and imaged using high frequency ultrasound. Each shoulder was isolated postmortem, and the ultrasonographic and gross anatomy was studied during dissection. The ultrasonographic appearance of the shoulder specimens was similar to that found in the live dogs. Twenty-four shoulders isolated postmortem from 12 variably sized dogs were also used to characterize the normal ultrasound anatomy over a range of sizes. Important anatomic structures that could be consistently evaluated were the biceps tendon and bursa, the bicipital groove surface, the supraspinatous tendon, the infraspinatous tendon, the teres minor tendon, and the caudal aspect of the humeral head. Results of ultrasonographic examination of 4 dogs with shoulder lameness are described to illustrate some applications of canine shoulder ultrasonography in the evaluation of the canine shoulder. In these dogs, ultrasound was a valuable tool to evaluate effusion and synovial proliferation within the bicipital bursa, supraspinatous and biceps tendinitis, biceps tendon strain, and dystrophic calcification.     

NORMAL ULTRASONOGRAPHIC ANATOMY OF THE CANINE NECK

High-resolution, real-time ultrasonographic examinations of the neck were performed on eight normal dogs maintained under general anesthesia. Water-soluble dye was injected into imaged structures under sonographic guidance in two dogs. The anatomy of the neck was verified at postmortem by visualization of dye deposited in the injected structures. Anatomical mapping was then completed by performing complete cervical ultrasound examinations in the remaining six dogs. Normal ultrasonographic anatomy of the canine neck and major anatomic landmarks useful in clinical imaging are described.     

ULTRASONOGRAPHIC DIAGNOSIS OF PORTAL VEIN THROMBOSIS IN FOUR DOGS

Ante mortem diagnosis of portal vein thrombosis was determined ultrasonographically in four dogs. In each dog the thrombus was visible in two-dimensional, grey-scale images of the portal vein obtained through a right intercostal window. Duplex-Doppler measurements and color-Doppler images provided information about the effects of thrombosis on portal blood flow. Reduced portal blood flow compatible with portal hypertension was detected in three dogs. A hypercoagulable state was probably involved in the pathogenesis of portal vein thrombosis in two dogs, one with pancreatitis and gastrointestinal blood loss and another with protein-losing nephropathy and probable immune-mediated anemia. The third dog had chronic ehrlichiosis; thrombosis was probably secondary to vasculitis. The remaining dog had thrombosis secondary to invasion of the portal vein by a recurrent duodenal neoplasm. This dog was euthanized because the tumor was considered inoperable. The dog with pancreatitis developed acute portal hypertension due to obstruction of the portal vein by the thrombus and was euthanized. The dogs with protein-losing nephropathy and ehrlichiosis were treated medically and recovered. Although portal vein thrombosis is uncommon, this complication should be considered in dogs with a variety of abdominal or systemic disorders. Ultrasonography is a practical method for diagnosis of portal vein thrombosis and detection of the underlying cause.     

ULTRASONOGRAPHIC ANATOMY OF THE BRACHIAL PLEXUS AND MAJOR NERVES OF THE CANINE THORACIC LIMB

A technique for ultrasonography of the brachial plexus and major nerves of the canine thoracic limb is described based on examination of five canine cadavers and three healthy dogs. The ventral branches of the spinal nerves that contribute to the brachial plexus are identifiable at their exit from the intervertebral foramina. These nerves may be followed distally, cranial to the first rib, until they form the brachial plexus. The musculocutaneous, ulnar, and median nerves are identified on the medial aspect of mid‐humerus and followed proximally to the axillary region and distally to the elbow. The radial nerve, formed by multiple nerve components, is seen on the mediocaudal aspect of the humerus. Nerves appear as hypoechoic tubular structures with an internal echotexture of discontinuous hyperechoic bands, surrounded by a thin rim of highly echogenic tissue. Improved understanding of the ultrasonographic anatomy of the brachial plexus and its main branches supports clinical use of this modality.     

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.     

ULTRASONOGRAPHIC DIAGNOSIS OF PORTOSYSTEMIC SHUNTING IN DOGS AND CATS

The value of ultrasonography was evaluated in 85 dogs and 17 cats presented with a clinically suspected portosystemic shunt (PSS). A PSS was confirmed in 50 dogs and nine cats (single congenital extrahepatic in 42, single congenital intrahepatic in 11, and multiple acquired in six). Six dogs and one cat had hepatic microvascular dysplasia, and 29 dogs and seven cats had a normal portal system. Ultrasonography was 92% sensitive, 98% specific, and had positive and negative predictive values of 98% and 89%, respectively, in identifying PSS, with an overall accuracy of 95%. When a PSS was identified with ultrasonography, extrahepatic, intrahepatic, and multiple acquired PSS could be correctly differentiated in 53/54 patients (98%). The combination of a small liver, large kidneys, and uroliths had positive and negative predictive values of 100% and 51% for the presence of a congenital PSS in dogs. The portal vein/aorta (PV/Ao) and portal vein/caudal vena cava (PV/ CVC) ratios were smaller in animals with extrahepatic PSSs compared with animals with microvascular dysplasia, intrahepatic PSSs and those without portal venous anomalies (P<0.001). All dogs and cats with a PV/Ao ratio of < or = 0.65 had an extrahepatic PSS or idiopathic noncirrhotic portal hypertension. Dogs and cats with PV/Ao and PV/CVC ratios of > or = 0.8 and > or = 0.75, respectively, did not have an extrahepatic PSS. Reduced or reversed portal flow was seen in four of four patients with multiple acquired PSSs secondary to portal hypertension. The presence of turbulence in the caudal vena cava of dogs had positive and negative predictive values of 91% and 84%, respectively, for the presence of any PSS terminating into that vein.     

ULTRASONOGRAPHIC DIAGNOSIS OF CONGENITAL PORTOSYSTEMIC SHUNTS IN DOGS: RESULTS OF A PROSPECTIVE STUDY

The aims of this study were to determine if accurate diagnosis of congenital portosystemic shunt was possible using two dimensional, grey-scale ultrasonography, duplex-Doppler, and color-flow Doppler ultrasonography in combination, and to determine if dogs with congenital portosystemic shunts have increased or variable mean portal blood flow velocity. Eighty-two dogs with clinical and/or clinicopathologic signs compatible with portosystemic shunting were examined prospectively. Diagnosis of congenital portosystemic shunt was subsequently confirmed in 38 of these dogs using operative mesenteric portography: 14(37%) dogs had an intrahepatic shunt and 24(63%) had an extrahepatic shunt. Ultrasonography had a sensitivity of 95%, specificity of 98%, and accuracy of 94%. Ultrasonographic signs in dogs with congenital portosystemic shunts included small liver, reduced visibility of intrahepatic portal vessels, and anomalous blood vessel draining into the caudal vena cava. Correct determination of intra - versus extrahepatic shunt was made ultrasonographically in 35/38 (92%) dogs. Increased and/or variable portal blood flow velocity was present in 21/30 (70%) dogs with congenital portosystemic shunts. In one dog with an intrahepatic shunt the ultrasonographic diagnosis was based partly on finding increased mean portal blood flow velocity because the shunting vessel was not visible. Detection of the shunting vessel and placement of duplex-Doppler sample volumes were facilitated by use of color-flow Doppler. Two-dimensional, grey-scale ultrasonography alone is sufficient to detect most intrahepatic and extrahepatic shunts; sensitivity is increased by additional use of duplex-Doppler and color-flow Doppler. Increased and/or variable portal blood flow velocity occurs in the majority of dogs with congenital portosystemic shunts.     

ULTRASONOGRAPHIC APPEARANCE OF CANINE GASTRIC POLYPS

Benign gastric polyps are uncommon in dogs and most are discovered incidentally. Polyps protruding into the pyloric antrum can cause gastric outflow obstruction. Clinical and ultrasonographic findings in seven dogs with histologically confirmed benign mucosal gastric polyps were reviewed. Sonographic findings such as shape, size, echogenicity, location, evidence of gastric wall thickening, wall layering, and size of regional lymph nodes were recorded. Five sessile and two pedunculated masses of different sizes (range 7–60 mm) and echogenicities were found. They primarily arose from the mucosal layer and protruded into the gastric lumen. Only one dog had a large inhomogeneous mass with a poorly visualized gastric wall layering. The polyps were all single, and were located in the pyloric antrum in six out of seven dogs. Although the ultrasonographic appearance allowed a presumptive diagnosis of mucosal gastric polyp, the final diagnosis was determined from histopathologic examination.