ULTRASONOGRAPHIC EVALUATION OF BILIARY CYSTADENOMAS IN CATS

The purpose of this study was to describe the ultrasonographic appearance of biliary cystadenomas in cats and compare the findings to a similar rare form of liver tumor in humans. Biliary cystadenomas are uncommon, benign liver tumors of older cats that may occur as focal or multifocal cystic lesions within the liver. The records of 10 cats which had abdominal ultrasonography and histologic diagnosis of biliary cystadenoma were reviewed. The average age of affected cats was 13.3 years (range 10-16 years). Eight cats were neutered males and two were neutered females. In three cats, the tumors were not seen ultrasonographically due to their small size or from being obscured by near-field reverberation echoes. The remaining seven cats had solitary (4 cats) or multifocal (3 cats) masses corresponding to variable ultrasonographic patterns: multilocular masses containing thin-walled cysts, hyperechoic masses with cystic components, or masses of mixed echogenicity with cystic components. The masses had variable ultrasonographic patterns when multifocal disease was present. Recognizable cysts were evident somewhere within the tumors seen ultrasonographically, although sometimes the cysts appeared very small. The biliary cystadenomas were thought to be clinically silent. Although liver enlargement or a cranial abdominal mass was palpable in 4 cats, no consistent trend of clinical signs, CBC or serum biochemical abnormalities could be directly attributed to biliary cystadenoma. The treatment of choice is surgical resection of the tumor, as continued growth may compress adjacent vital structures within the liver. The differential diagnosis of biliary cystadenomas from other cystic liver lesions such as hepatic cysts, hematomas, abscesses, parasitic cysts, or other liver tumors is discussed.     

SONOGRAPHIC ASSESSMENT OF GALLBLADDER VOLUME IN NORMAL CATS

We quantified gallbladder volume in 30 clinically healthy, fasted, cats, using an ellipsoid formula. All cats had a complete blood count and serum chemistry profile performed. Fasting times before sonography ranged from 12 to 16 h. The median gallbladder volume was 2.42 ml, with a range of 0.84–4.50 ml. The mean gallbladder volume was 2.41 ml. This reference range will assist clinicians when evaluating cats with hepatobiliary disease or suspected extrahepatic biliary obstruction.     

ULTRASONOGRAPHIC FEATURES OF EXTRAHEPATIC BILIARY OBSTRUCTION IN 30 CATS

The goals of our study were to review the ultrasonographic features of spontaneous extrahepatic biliary obstruction in cats and to determine whether these features can assist in differentiating tumor, inflammation, and choleliths as the cause of obstruction. Thirty cats with a presurgical ultrasound examination an dconfirmed extrahepatic biliary obstruction were studied. A common bile duct diameter over 5 mm was present in 97% of the cats with extrahepatic biliary obstruction. Gallbladder dilation was seen in < 50% of the cats. Ultrasound identified all obstructive choleliths (calculus or plugs) in the common bile duct. However, neither common bile duct diameter nor appearance or any other ultrasonographic feature allowed differentiation between tumor and inflammation as the cause of obstruction. A short duration of clinical signs (10 days or less) seemed to be associated with obstructive cholelithiasis.     

ULTRASONOGRAPHIC CHARACTERISTICS OF LIPIDURIA IN CLINICALLY NORMAL CATS

Echoes are frequently seen in the urinary bladder of cats during abdominal ultrasound. These have been attributed to hematuria, pyuria, crystalluria, and lipid. However, sonographic findings have not been previously correlated with urinalysis. We prospectively evaluated 40 clinically normal cats via ultrasound, serum chemistry, and urinalysis. Thin layer chromatography was performed on the urine to determine the amount (mg) of lipid subfractions including diacylglycerol, triglyceride, phospholipid, free fatty acid, cholesterol, and cholesterol ester. Ninety percent (36/40) of the cats in our population had sonographic echoes suspended in the urinary bladder, with most having a subjective score of mild echoes (n = 20). None of the sonographic echoes were gravity dependent or caused distal acoustic shadowing, reverberation, or twinkle artifact. Of the cats with sonographic echoes in the urine, 66% (24/36) had no significant findings on urinalysis other than the presence of lipid. The total amount of subjective sonographic echoes was not significantly related to the total amount of fat measured on thin layer chromatography or the number of lipid droplets seen on urinalysis. An increased amount of urine diacylglycerol was significantly associated with clumping of echoes (P = 0.02) and the amount of lipid droplets seen on urinalysis (P = 0.04). An association between increased amounts of urine diacylglycerol and the amount of echoes seen on ultrasound approached significance (P = 0.05). Findings from this study support previously published theories that sonographic echoes within the urinary bladder of clinically normal cats may be due to urine lipid.     

SONOGRAPHIC EVALUATION OF URINARY BLADDER WALL THICKNESS IN NORMAL DOGS

Urinary bladder wall thickness was evaluated by ultrasonography in 16 normal dogs. Sterile saline solution was administered via urinary catheters to control the degree of bladder distention. Bladder wall thickness was measured on static ultrasound images in 4 locations and at 3 degrees of bladder distention (minimal, mild, and moderate). Four randomized distention sequences with 3 distentions per sequence were performed on each dog and the data were analyzed using Williams' balanced Latin square. Mean bladder wall thickness was 2.3 mm in minimally distended bladders (0.5 ml/kg saline), 1.6 mm in mildly distended bladders (2 ml/kg saline) and 1.4 mm in moderately distended bladders (4 ml/kg saline). Mean bladder wall thickness increased significantly with increasing body weight and with decreasing bladder distention. The caudoventral measurement location produced a statistically significant smaller measurement, with a difference of 0.3 mm. Sex did not affect bladder wall thickness. Distention sequence and repetition of distentions did not affect bladder wall thickness.     

ULTRASONOGRAPHIC EVALUATION OF RENAL AUTOGRAFTS IN NORMAL CATS

The purpose of this study was to determine changes in resistive index (RI) and renal size that occur in normal feline kidney autografts in the immediate post-transplant period. Qualitative changes in renal parenchymal echogenicity and pelvic dilation were also noted, although this was not a major focus of the study. Fourteen domestic short-haired cats underwent bilateral nephrectomies followed by an autograft of the right kidney to either the aorta or external iliac artery. Due to post-operative complications, only nine of these cats completed the study. Ultrasonographic determination of the RI and renal size was made before transplantation and on days 1, 4, 7, 10, and 13 following transplantation. No significant changes in renal RI were identified during the study. Renal size increased significantly, peaking at 63% above baseline on day 7, and stayed elevated at 50% above baseline on day 13. There was no evidence of rejection or other abnormalities found on histologic evaluation of the transplanted kidneys. It was concluded that the RI of normal feline renal autografts does not significantly change in the immediate post-operative period. However, significant renal enlargement, likely due to a combination of post-operative edema and hypertrophy, does occur. This study provides baseline information for comparison with feline allografts in the immediate post-transplant period.     

ULTRASONOGRAPHIC OBSERVATION OF SECRETIN-INDUCED PANCREATIC DUCT DILATION IN HEALTHY CATS

Secretin is a polypeptide hormone that stimulates secretion of bicarbonate from the exocrine pancreas and, in healthy human subjects, causes transient pancreatic duct dilation observable sonographically. In humans with chronic pancreatitis, secretin administration fails to cause pancreatic duct dilation, theoretically due to the restrictive effects of periductal fibrosis. We characterized the effect of exogenous secretin administration on the width of the pancreatic duct in nine healthy domestic cats. Cats were given a commercially available secretin product (ChiRho Stim™) while the pancreatic duct was monitored sonographically. Mean pancreatic duct diameter increased from 0.77±0.33 to 1.42±0.40 mm after secretin administration ( P =0.0017). The mean percent increase in pancreatic duct diameter over basal diameter for all time points up to 15 min postsecretin administration was 101.9±58.8%. Applicability of this technique to diagnose chronic pancreatitis in cats will need to be investigated.     

BILOBED GALLBLADDER IN A CAT: ULTRASONOGRAPHIC APPEARANCE

A five-month-old male domestic shorthair cat presented with a history of vomiting for 4 days. An ultrasound examination of the abdomen was performed as part of the diagnostic workup. The gallbladder appeared to be bilobate. The cat died the following day from renal failure. At necropsy, a bilobed gallbladder was confirmed and considered to be a congenital anomaly unrelated to the cat's death.     

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 CHARACTERISTICS OF THE CISTERNA CHYLI IN EIGHT DOGS AND FOUR CATS

Ultrasonography of the cisterna chyli has been used in humans to diagnose increased lymphatic flow or lymph flow obstruction and to guide percutaneous embolization of the thoracic duct via the cisterna chyli. The aim of this study was to describe the ultrasonographic characteristics of the dorsal portion of cisterna chyli in dogs and cats with chylous ascites or chylothorax and in a group of healthy dogs and cats. The aorta and the cranial mesenteric artery were used as anatomic landmarks. Ultrasonography was performed before and 2 h after a fatty meal in healthy dogs and cats. The visualized structure was confirmed to be a dilated cisterna chyli at necropsy in a dog with chylous ascites. The confirmed or presumed cisterna chyli was consistently detected using ultrasonography in nonfasted healthy animals and clinically affected animals and appeared as an anechoic tubular structure, without detectable flow, at the right dorsolateral aspect of the aorta. It had a similar ultrasonographic appearance in patients with chyloabdomen and in nonfasted healthy dogs and cats. There was considerable overlap in diameters of the cisterna chyli for affected and healthy animals. The shape and size of the cisterna chyli in an individual animal were variable during the same ultrasound examination and between different examinations. This study demonstrated the appearance of the presumed dorsal portion of the cisterna chyli by ultrasonography and might provide useful preliminary data for further studies into the feasibility of ultrasound‐guided injections or aspirations of the cisterna chyli in dogs and cats.     

ULTRASONOGRAPHIC AND PATHOLOGIC FEATURES OF INTESTINAL SMOOTH MUSCLE HYPERTROPHY IN FOUR CATS

The ultrasonographic findings for four cats with intestinal smooth muscle hypertrophy are described. In two cats, intestinal smooth muscle hypertrophy was associated with chronic enteritis. In the remaining two cats, intestinal smooth muscle hypertrophy affected the intestinal tract proximal to stenosis due to alimentary lymphoma and an intestinal foreign body, respectively. Moderate increased thickness of the affected intestinal wall, measuring 7-8 mm, was evident on abdominal ultrasonographic examination of all subjects. In addition, the ultrasonographic five-layered feature of the intestinal wall was maintained, and only the muscular layer appeared thickened. Abdominal ultrasound allowed a presumptive diagnosis of intestinal smooth muscle hypertrophy that was confirmed histologically in all cats.     

ULTRASONOGRAPHIC FINDINGS IN DOGS AND CATS WITH GASTROINTESTINAL PERFORATION

A retrospective study was performed to evaluate the sonographic features of gastrointestinal (GI) perforation in dogs and cats. Sonographic findings in 19 animals (14 dogs and 5 cats) included regional bright mesenteric fat (19), peritoneal effusion (16), fluid-filled stomach or intestines (12), GI wall thickening (11), presence of free air (9), loss of GI wall layering (9), regional lymphadenopathy (8), reduced GI motility (7), pancreatic changes (4), corrugated intestines (4), presence of a mass (3), presence of a foreign body (3), and mineralization of the gastric wall (1). In 14 patients, "perforation" was listed as a differential diagnosis by the sonographer. Abdominal radiographs and radiographic reports were available for 14 patients. Radiographic findings were decreased serosal detail (12), free air (8), peritoneal contrast medium (1), and suspected foreign body (1). GI perforation was listed as radiographic diagnosis in eight patients, seven of which had evidence of pneumoperitoneum, and one had leakage of contrast material on an upper GI study. In 9/14 patients with radiography, "GI perforation" was listed as a sonographic diagnosis. In three patients in which free air was diagnosed sonographically, radiographs were either not available (2) or the presence of free air was not detected at presentation (1). Peritoneal fluid analysis was performed in nine patients, five of which were identified as septic inflammation, and the remaining four were classified as neutrophilic inflammation with no etiologic agent identified. The histologic or surgical diagnoses were as follows: three intestinal surgical dehiscence; one percutaneous endoscopic gastrostomy tube site leakage; one duodenal adenocarcinoma; one ileocolic lymphoma; one trichobezoar; one ascarid impaction; and one bobby pin foreign body. In the remaining 10 patients, a focal area of gastric/intestinal ulceration or transmural necrosis with perforation was identified without evidence of an underlying cause.     

ULTRASONOGRAPHIC EVALUATION OF GASTROINTESTINAL DISEASES IN SMALL ANIMALS

Sonographic findings of 18 dogs and four cats with gastrointestinal (GI) diseases were reviewed. Wall thickness, wall layer identification, wall symmetry, extension of the lesion, nature of the GI contents, motility, and regional and/or systemic involvement were recorded for each animal. Ultrasonographic appearance of gastrointestinal neoplasms, gastrointestinal obstruction, ileus, intussusception, inflammatory GI diseases, and congenital disorders are discussed.     

ULTRASONOGRAPHIC APPEARANCE AND CLINICAL FINDINGS IN 14 DOGS WITH GALLBLADDER MUCOCELE

Fourteen dogs with enlarged gallbladders and immobile stellate or finely striated bile patterns on ultrasound are described. Smaller breeds and older dogs were overrepresented, with 4/14 Cocker Spaniels. Most dogs presented for nonspecific clinical signs such as vomiting, anorexia and lethargy. Abdominal pain, icterus and hyperthermia were the most common findings on physical examination. All dogs except one had serum elevation of total bilirubin and/or alkaline phosphatase, alanine aminotransferase and gamma glutamyl transferase. All dogs were diagnosed with a gallbladder mucocele upon histologic and/or macroscopic evaluation. Ultrasonographically, mucoceles are characterized by the appearance of the stellate or finely striated bile patterns and differ from biliary sludge by the absence of gravity dependent bile movement. On ultrasound, gallbladder wall thickness and wall appearance were variable and nonspecific. The cystic or common bile duct were normal sized in 5 dogs although all 5 had evidence of biliary obstruction at surgery or necropsy. Loss of gallbladder wall integrity and/or gallbladder rupture were present in 50% of the dogs, all located in the fundus. Gallbladder wall discontinuity on ultrasound indicated rupture whereas neither bile patterns predicted the likelihood of gallbladder rupture. Pericholecystic hyperechoic fat or fluid were suggestive of but not diagnostic for a gallbladder rupture. Cholecystectomy appears to be an appropriate treatment for mucoceles, if not to treat a gallbladder rupture, at least in most dogs to prevent it since gallbladder wall necrosis was identified by histology in 9 of 10 dogs. Mucosal hyperplasia was present in all gallbladders examined histologically. Positive aerobic bacterial culture was obtained from bile in 6 of 9 dogs. Cholecystitis was diagnosed histologically in 5 dogs and 4 dogs had signs of gallbladder infection solely upon bacterial bile culture. Gallbladder infection was not present with all the mucoceles suggesting that biliary stasis and mucosal hyperplasia may be the primary factors involved in mucocele formation. Based on the results of our study, we suggest two alternate courses of action in the presence of a distended gallbladder with an immobile ultrasonographic stellate or finely striated bile pattern: a cholecystectomy when clinical or biochemical signs of hepatobiliary disease are present or a medical treatment (antibiotics and choleretics) and patient monitoring by follow-up ultrasound examinations when the patient does not have clinical or biochemical abnormalities. An aerobic bile culture should be obtained in all patients, by ultrasound-guided fine needle aspirate or at surgery.     

REPEATABILITY AND REPRODUCIBILITY OF TRANSABDOMINAL ULTRASONOGRAPHIC INTESTINAL WALL THICKNESS MEASUREMENTS IN THOROUGHBRED HORSES

The aims of this study were to assess the repeatability and reproducibility of transabdominal ultrasonography to assess intestinal wall thickness in adult Thoroughbred horses (n=8). Ultrasonographic cineloops were captured by one examiner from each horse for five consecutive days. During each examination at least three cineloops were obtained for five different intestinal tract locations. Measurements were performed by three separate observers to assess reproducibility and measured on three separate occasions by three observers to evaluate short‐term repeatability. The repeatability of measurements from the duodenum (0.3 ± 0.04 cm), jejunum (0.29 ± 0.05 cm), ventral colon (0.37 ± 0.01 cm), and cecum (0.42 ± 0.03 cm) were good ( P >0.291). The reproducibility of measurements from the duodenum, jejunum, and ventral colon were good ( P >0.394). Reproducibility of measurement of the cecal wall was inadequate ( P =0.01), although the maximum difference between observers was 0.07 cm. It was possible to image all areas on all days, with the exception of the duodenum, which could not be imaged in one horse, on 1 day. Equine intestinal wall measurements are therefore repeatable and reproducible with the exception of reproducibility of the measurements of cecal wall. Although an accepted clinical technique, measurement of cecal wall thickness from intestinal ultrasound images in a clinical setting must be interpreted with care.     

ULTRASONOGRAPHIC ASSESSMENT OF SINCALIDE-INDUCED CANINE GALLBLADDER EMPTYING: AN AID TO THE DIAGNOSIS OF BILIARY OBSTRUCTION WINNER OF THE 1991 RESIDENT-AUTHORED PAPER AWARD SPONSORED BY THE AMERICAN COLLEGE OF VETERINARY RADIOLOGY

Gallbladder emptying studies using ultrasonography were performed on ten normal dogs, one normal control dog, three dogs with biliary obstruction and three dogs with nonobstructive hepatobiliary disease. An intravenous bolus of a synthetic cholecystokinin was used to induce emptying. The normal canine gallbladder emptied at least 40% of its volume within one hour of synthetic cholecystokinin (0.04 μg/kg) administration. Maximum response was seen within 5 to 20 minutes. The gallbladder in icteric dogs with nonobstructive hepatobiliary disease (1 cholecystitis, 1 cholangitis, 1 cholangiohepatitis) also emptied at least 40% of its volume within one hour. The obstructed gallbladder (1 chronic pancreatitis, 1 acute pancreatitis, 1 pancreatic mass) emptied less than 20% within one hour. A significant difference (p>0.05) in the maximum percent gallbladder emptying was found between the dogs with biliary obstruction and nonobstructed, icteric dogs. No side effects to the synthetic cholecystokinin were observed.     

COMPARISON BETWEEN ULTRASONOGRAPHIC AND CLINICAL FINDINGS IN 43 DOGS WITH GALLBLADDER MUCOCELES

Cholecystectomy is the current standard recommended treatment for dogs with gallbladder mucoceles. However, medical management with monitoring has also been recommended for asymptomatic dogs. The purpose of this retrospective study was to compare ultrasonographic patterns of gallbladder mucoceles with clinical disease status in a group of dogs. For each included dog, the ultrasonographic pattern of the mucocele was classified into one of six types: type 1, immobile echogenic bile; type 2, incomplete stellate pattern; type 3, typical stellate pattern; type 4, kiwi like pattern and stellate combination; type 5, kiwi like pattern with residual central echogenic bile; and type 6, kiwi like pattern. A total of 43 dogs were included. Twenty‐four dogs, including 11 dogs with gallbladder rupture, were symptomatic. Nineteen dogs were asymptomatic. Cholecystectomy (n = 19), medical therapy (n = 17), or monitoring (n = 6) treatments were applied according to clinical signs and owners’ requests. One dog suspected of having gallbladder rupture was euthanized. Frequencies of gallbladder mucocele patterns were as follows: type 1 = 10 (23%), type 2 = 13 (30%), type 3 = 5 (12%), type 4 = 11 (26%), type 5 = 4 (9%), and type 6 = 0. In dogs with gallbladder rupture, type 2 (8/13) was the most common. No significant correlations were found between ultrasonographic patterns of gallbladder mucoceles and clinical disease status or gallbladder rupture. Findings indicated that ultrasonographic patterns of gallbladder mucoceles may not be valid bases for treatment recommendations in dogs.     

THE SCINTIGRAPHIC EVALUATION OF SOLID PHASE GASTRIC EMPTYING IN NORMAL CATS

The gastric emptying half-time of solid food in normal cats was determined using a scintigraphic technique. ^99mTc-sulfur colloid was applied to dry food. Sequential images were acquired post prandial, and the gastric emptying half-time was determined for several different acquisition and processing parameters. Good correlation was found between different acquisition and processing methods, some of which made use of edge detection applications, while others used different views, or number of views from which the gastric emptying half-time was calculated. The mean ± standard deviation, (range) and median of the gastric emptying half-time determined using the geometric mean of total counts in hand-drawn regions of interest from the lateral and ventral images were 2.47 × 0.71, (1.42–3.61) and 2.37 hours respectably.     

DOPPLER ULTRASONOGRAPHIC ESTIMATION OF RENAL AND OCULAR RESISTIVE AND PULSATILITY INDICES IN NORMAL DOGS AND CATS

Resistive index (RI) and pulsatility index (PI) are indirect measurements of blood flow resistance that may be used to evaluate vascular changes in renal and ophthalmologic diseases. To our knowledge, no reports are available describing values for renal and ocular PI index in the unsedated dog and ocular RI and PI indices in the unsedated cat. The purpose of this study was to measure normal values for both intrarenal and ocular RI and PI within the same subject in unsedated clinically normal dogs and cats. Twenty-seven dogs and 10 cats were considered healthy by means of physical examination, CBC, biochemical profile, urinalysis, and ultrasonography. Systolic blood pressure was measured by Doppler ultrasonography. Intrarenal and ocular arteries were scanned by pulsed Doppler ultrasonography to calculate RI and PI. No significant differences were noted between the values obtained for the right vs. the left kidney and eye. The upper values of these indices were calculated as mean+2 standard deviations resulting in 0.72 and 1.52 for dog renal RI and PI; 0.7 and 1.29 for cat renal RI and PI; 0.76 and 1.68 for dog ocular RI and PI; and 0.72 and 1.02 for cat ocular RI and PI.     

ULTRASONOGRAPHIC APPEARANCE OF SPLENIC DISEASE IN 101 CATS

The sonographic findings in 101 cats with splenic abnormalities are presented. Diagnosis was made by ultrasound-guided fine needle aspirate or fine-needle biopsy (n = 91), ultrasound-guided core biopsy (n = 1), surgical core biopsy (n = 1), or necropsy (n = 10). Two cats had more than one diagnostic procedure (fine needle aspirate and necropsy or core biopsy and necropsy). The splenic abnormalities included lymphosarcoma (n = 30), mast cell tumor (n = 27), extramedullary hematopoiesis and/or lymphoid hyperplasia (n = 27), epithelial tumors (n = 6), mesenchymal tumors (n = 4), malignant histiocytosis (n = 2), myeloproliferative disease (n = 2), pyogranulomatous inflammation (n = 2), erythroleukemia (n = 1), eosinophilic syndrome (n = 1), hematoma (n = 1), and granulomatous splenitis (n = 1). Three cats had more than one splenic abnormality (mast cell tumor and metastatic carcinoma, pyogranulomatous inflammation and lymphoid hyperplasia, histiocytic lymphosarcoma, and lymphoid hyperplasia). Pathognomonic changes were not seen for any of the diseases.