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.     

Evaluation of plasma protein C activity for detection of hepatobiliary disease and portosystemic shunting in dogs

OBJECTIVE: To determine the diagnostic value of protein C (PC) for detecting hepatobiliary disease and portosystemic shunting (PSS) in dogs. DESIGN: Prospective study. ANIMALS: 238 clinically ill dogs with (n = 207) and without (31) hepatobiliary disease, including 105 with and 102 without PSS. PROCEDURES: Enrollment required routine hematologic, serum biochemical, and urine tests; measurement of PC activity; and a definitive diagnosis. Total serum bile acids (TSBA) concentration and coagulation status, including antithrombin activity, were determined in most dogs. Dogs were grouped into hepatobiliary and PSS categories. Specificity and sensitivity were calculated by use of a PC cutoff value of 70% activity. RESULTS: Specificity for PC activity and TSBA concentrations was similar (76% and 78%, respectively). Best overall sensitivity was detected with TSBA, but PC activity had high sensitivity for detecting PSS and hepatic failure. Protein C activity in microvascular dysplasia (MVD; PC > or = 70% in 95% of dogs) helped differentiate MVD from portosystemic vascular anomalies (PSVA; PC < 70% in 88% of dogs). A receiver operating characteristic curve (PSVA vs MVD) validated a useful cutoff value of < 70% activity for PC. CONCLUSIONS AND CLINICAL RELEVANCE: Combining PC with routine tests improved recognition of PSS, hepatic failure, and severe hepatobiliary disease and signified a grave prognosis when coupled with hyperbilirubinemia and low antithrombin activity in hepatic failure. Protein C activity can help prioritize tests used to distinguish PSVA from MVD and sensitively reflects improved hepatic-portal perfusion after PSVA ligation.     

Hepatic lesions of a standard poodle dog with intrahepatic portosystemic shunt

A 1-year-and-3-month-old, male standard poodle dog with intrahepatic portosystemic shunt (PSS) was autopsied. Nineteen regions of the liver were prepared for detailed examination, and the distribution of hepatic lesions caused by PSS was studied in the liver of this dog. Histopathologically, the liver revealed a variety of hepatic lesions including lipogranulomas in the hepatic parenchyma, and a ductular reaction and microvascular proliferation in portal areas. The distribution of the lesions was not significantly different among liver regions. It is concluded that, in the present case, hepatic lesions caused by PSS are independent of shunt location, and are distributed equally in the liver.     

Transvenous retrograde portography for identification and characterization of portosystemic shunts in dogs

Transvenous retrograde portography for identification and characterization of portosystemic shunts in dogs A method for transvenous retrograde portography (TRP) in dogs suspected to have a portosystemic shunt (PSS) and results in 20 dogs are described. For TRP, dogs were anesthetized and positioned in left lateral recumbency A dual-lumen balloon-tipped catheter was inserted into the right jugular vein and advanced into the azygos vein. The balloon was inflated to occlude the azygos vein, and contrast material was injected during fluoroscopic evaluation. The catheter was then positioned in the caudal vena cava just cranial to the diaphragm. The balloon was again inflated to occlude the vena cava, and contrast material was again injected. Once a shunt was identified, selective catheterization was attempted with a guide wire and angled catheter. A PSS was identified in 18 of the 20 dogs. In 10 of the 18, the shunt vessel could be selectively catheterized, allowing measurement of portal pressures while the shunt was occluded with the balloon. In 1 dog, results of TRP were normal, but subsequent exploratory celiotomy revealed a single extrahepatic PSS, which was surgically attenuated. The other dog in which results of TRP were normal did not have a macroscopic PSS. In dogs suspected to have a PSS, TRP may be a useful adjunctive diagnostic test that is less invasive than operative mesenteric vein portography and allows measurement of portal pressures before and after temporary shunt occlusion.     

Acquired portosystemic shunting in two cats.

Acquired portosystemic shunts (PSS) are a clinical entity distinct from congenital PSS. Their apparent incidence in cats is low, which may reflect the rarity of predisposing hepatic parenchymal disease, such as cirrhosis, in this species. Two cats with acquired PSS associated with primary hepatobiliary disease are described. Relevant findings in acquired PSS are discussed, as are potential reasons for the apparently low incidence in the cat.     

BRAIN MAGNETIC RESONANCE IMAGING CHARACTERISTICS IN DOGS AND CATS WITH CONGENITAL PORTOSYSTEMIC SHUNTS

Animals with a portosystemic shunt (PSS) often have neurologic abnormalities. Diagnostic imaging, including brain magnetic resonance (MR) imaging, is not performed routinely in these animals. In this study, brain MR images were obtained in 13 dogs and three cats with a PSS, and in 15 dogs and five cats that were neurologically normal and used as controls. All animals with a PSS had widened sulci. In addition, 10 out of 13 dogs with a PSS and one out of three cats with a PSS had hyperintense focal areas in the lentiform nuclei on T1-weighted (T1W) images, which did not enhance after intravenous gadolinium. Following surgical correction of the PSS, MR imaging examinations were repeated in one dog and one cat. The hyperintensity of the lentiform nuclei had decreased. This study indicates that MR imaging findings of widened sulci and hyperintensity of the lentiform nuclei on T1W images may be found in dogs and cats with a PSS.     

Determination of inheritance of single congenital portosystemic shunts in Yorkshire terriers

A hereditary basis for congenital portosystemic shunts (PSS) in Yorkshire terriers was explored through record and pedigree analysis and a breeding trial. The odds ratio for PSS in Yorkshire terriers was 35.9 times greater than for all other breeds combined. Wright's coefficient of inbreeding was approximately twice as high for Yorkshire terriers with PSS as compared to normal members of the breed (P=0.09). No common ancestors were found that were significant to the PSS group. Two affected Yorkshire terriers were bred and produced two normal puppies. Congenital PSS appears to be hereditary in Yorkshire terriers; however, the mechanism of inheritance has yet to be elucidated.     

Characterization of Hepatoportal Microvascular Dysplasia in a Kindred of Cairn Terriers

Hepatoportal microvascular dysplasia (MVD), a congenital disorder of the hepatic vasculature, is described in a kindred of Cairn Terrier dogs. Cairn Terrier dogs (n = 165) were evaluated using the serum bile acid test. Affected dogs, identified by abnormal fasting or postprandial serum bile acid concentrations, were divided into 2 groups. Group 1 dogs (n = 147) were used for pedigree analysis. Group 2 dogs (n = 18) were characterized on the basis of history, physical examination, clinicopathologic studies, diagnostic imaging of the liver and portal circulation, and hepatic histopathology. Group 2 contained control dogs (n = 2), dogs with hepatoportal MVD (n = 11), and dogs with macroscopic portosystemic vascular anomalies (PVSA) (n = 5). With the exception of high serum bile acid concentrations, dogs with hepatoportal MVD were indistinguishable from control dogs on the basis of history, physical examination, clinicopathologic findings, survey abdominal radiography, abdominal ultrasound, or transcolonic scintigraphy. Contrast portography in dogs with MVD revealed abnormalities of terminal twigs of the portal vasculature with out large intrahepatic or extrahepatic shunting vessels. Histopathologic abnormalities in dogs with hepatoportal MVD were similar to those reported for dogs with PSVA. Pedigree analysis suggested an autosomal inheritance for MVD. Dogs with MVD had high serum bile acid concentrations, abnormal indocyanine green clearance, and hepatic pathology suggestive of PSVA, but they lacked characteristic clinical findings of PSVA. The clinical significance of MVD is unclear. Dogs with MVD were clinically normal when evaluated but long-term follow-up is not yet available. Dogs with hepatoportal MVD should be identified at an early age to avoid confusion in future diagnostic evaluations. J Vet Intern Med 1996:10:219–230. Copyright © 1996 by the American College of Veterinary Internal Medicine .     

USE OF MAGNETIC RESONANCE ANGIOGRAPHY FOR DIAGNOSIS OF PORTOSYSTEMIC SHUNTS IN DOGS

A prospective study was conducted to determine the sensitivity and specificity of diagnosis of portosystemic shunts (PSS) and the accuracy of anatomically locating single congenital PSS in dogs using magnetic resonance angiography (MRA). MRA was performed on 10 normal dogs and 23 dogs with PSS. Sensitivity and specificity of MRA to diagnose any shunt among all dogs were 80% and 100%, respectively. Among dogs identified with PSS, sensitivity and specificity of MRA for diagnosis of multiple extrahepatic shunts were 63% and 97%, respectively, and for diagnosis of single congenital shunts were 79% and 100%, respectively. Using MRA, radiologists correctly identified shunts as extrahepatic or intrahepatic in 83% of patients and correctly identified the origin and insertion of the shunts in 57% and 97% of patients, respectively. Use of MRA is specific for diagnosis of PSS and is a sensitive indicator of anatomic location of single congenital portosystemic shunts.     

Microcytosis and Iron Status in Dogs With Surgically Induced Portosystemic Shunts

Microcytosis is common in dogs with congenital portosystemic shunts (PSS) and acquired liver disease. The objective of this study was to determine if microcytosis could be induced in normal dogs by surgical creation of PSS, and to characterize the changes in hematology and iron status. Hematocrit, mean cell volume, mean cell hemoglobin, and mean cell hemoglobin concentration decreased linearly from 45.5%. 69.1 fL, 22.8 g/dL and 33.1% to 39.5%. 55.9 fL, 17.8 g/dL and 31.9%. respectively, 18 weeks after creation of PSS. The erythrocyte count did not change, but red cell distribution widths indicated a shift to a heterogenous population with decreased volume. Mean cell volume and mean cell hemoglobin decreased rapidly after induction of PSS and were significantly ( P < .05) different from presurgery values within 2 weeks. Serum iron and copper concentrations and total iron binding capacity were decreased in dogs with PSS. Liver iron concentration doubled after creation of PSS, with the majority of stainable iron located in Kupffer cells. The changes in erythrocyte indices and measures of iron status in dogs with surgically induced PSS were similar to those in dogs with congenital PSS. Microcytosis developed rapidly in dogs after induction of PSS. These results indicate that iron deficiency was not the cause of microcytosis in these dogs.     

Feline urate urolithiasis: a retrospective study of 159 cases

The objective of the study was to characterize the signalment, clinicopathologic data, and diagnostic imaging of cats with urate urolithiasis, as well as the salts of uric acid present in the uroliths. A retrospective analysis of feline urate uroliths submitted to the GV Ling Urinary Stone Analysis Laboratory between 2000 and 2008 was included. From these data, records were assimilated from referring veterinarians (143); furthermore, all recorded cases from within the William R Pritchard Veterinary Medical Teaching Hospital (16) were included. Median values for the complete blood count and chemistry panels available were within the reference intervals, when provided, with only a few outliers present. Of all cases evaluated, seven had a portosystemic shunt (PSS). Cats with urate uroliths and a PSS were younger than cats without a PSS (2 years vs 7 years). The pathogenesis of urate uroliths in cats is poorly understood. Most cats were not completely evaluated for a PSS, however, clinicopathologic parameters indicating hepatic dysfunction were seldom noted; more sensitive diagnostics such as serum bile acids were rarely performed to confirm or negate the presence of a shunt. Studies are warranted to evaluate pathogenesis of urate uroliths to tailor proper management and breeding strategies.     

Osteochondral dysplasia of the coxofemoral joints in a Friesian foal: Clinical findings and methods of diagnosis

Diseases of the coxofemoral (hip) joint are infrequently diagnosed in horses. Most cases are presented as an unilateral condition and usually are of traumatic origin. This case report describes a Friesian foal with a clinically obvious thoracolumbar kyphosis, combined with a weight‐shifting stance and a shortened stride of both hindlimbs. General clinical and lameness examinations, computed tomographic examination of the pelvis, and macroscopic and histopathological examinations of the coxofemoral joints were performed. This revealed a final, phenotypical diagnosis of a primary osteochondral dysplasia of both coxofemoral joints with secondary osteoarthritis. Similar to the occurrence of this condition in other species and considering the small genetic basis of the Friesian horse breed, a genetic predisposing factor is suspected to play a key role in the developing mechanism of dysplastic coxofemoral joint disease in horses as illustrated with this case. Computed tomography scanning appears to be a useful imaging technique in the detection of coxofemoral joint disease in small horses and foals.     

Histopathological characteristics of hepatic lipogranulomas with portosystemic shunt in dogs

In the canine liver with portosystemic shunts (PSS), focal lesions consisting of cells with cytoplasmic brown pigments and lipid vacuoles are often observed in the hepatic parenchyma. Termed lipogranulomas, their histopathological characteristics have been little studied. In the present study, we examined liver biopsy samples from 144 dogs (age: 3 months-16 years; 65 PSS and 79 non-PSS cases), and investigated the histopathological characteristics, incidence, and density of lipogranulomas. Lipogranulomas were detected histopathologically in 55.4% of PSS dogs. The lesions were then grouped into 3 types according to the amount of cytoplasmic lipid vacuoles and brown pigments. The pigments were positive for Berlin blue, PAS, and Sudan black B, but negative with the Hall method. The majority of the cells were immunohistochemically positive for macrophage scavenger receptor, class A (MSR-A), while no cells were positive for hepatocyte-antigen and albumin. The cytoplasmic pigments were recognized as electron-dense microgranular materials by electron microscopy. The incidence of lipogranulomas was significantly higher in the PSS group than non-PSS group when dogs less than 1 year old were excluded. The lipogranuloma density in the liver was significantly higher in the PSS group. It is concluded that lipogranulomas are frequently observed in liver biopsies of canine PSS especially in dogs more than 1 year old. The lesions consisted of Kupffer cells and/or macrophages, and the cytoplasmic brown pigments are ceroid and hemosiderin. The pathogenesis of lipogranuloma in PSS needs to be clarified.     

USE OF CONTRAST HARMONIC ULTRASOUND FOR THE DIAGNOSIS OF CONGENITAL PORTOSYSTEMIC SHUNTS IN THREE DOGS

Contrast harmonic ultrasound was used to determine macrovascular and perfusion patterns in three dogs with congenital extrahepatic solitary portosystemic shunts (PSS). With coded harmonic angiographic ultrasound, the size and tortuosity of the hepatic arteries were subjectively increased. Single pulse intermittent low-amplitude harmonic perfusion imaging provided contrast enhancement time-intensity curves from regions of interest in the liver. Mean (+/- standard deviation) peak perfusion times of dogs with PSS were significantly shorter (p = 0.01; 7.0 +/- 2.0 s) than reported in normal dogs (22.8 +/- 6.8 s). The contrast inflow slope for the dogs with PSS (14.6 +/- 3.7 pixel intensity units [PIU] was significantly (p = 0.05) larger than reported for normal dogs (3.6 +/- 1.4 PIU/s). These results indicate that combined coded harmonic angiographic and contrast harmonic perfusion sonography can be used to detect increased hepatic arterial blood flow as an indicator of PSS in dogs.     

Evaluation of a portocaval venograft and ameroid ring for the occlusion of intrahepatic portocaval shunts in dogs

OBJECTIVE:To evaluate the use of a portocaval venograft and ameroid constrictor in the surgical management of intrahepatic portosystemic shunts (PSS). STUDY DESIGN: Prospective, clinical study. Animal Population: Ten client-owned dogs with intrahepatic PSS. METHODS: Portal pressure was measured after temporary suture occlusion of the intrahepatic PSS. In dogs with an increase in portal pressure greater than 8 mm Hg, a single extrahepatic portocaval shunt was created using a jugular vein. An ameroid ring was placed around the venograft and the intrahepatic PSS was attenuated. Transcolonic pertechnetate scintigraphy was performed before surgery, 5 days after surgery, and 8 to 10 weeks after surgery. Dogs with continued portosystemic shunting were evaluated further by laparotomy or portography. Clinical outcome and complications were recorded. RESULTS: Mean (+/- SD) portal pressure increased from 6 +/- 3 to 19 +/- 6 mm Hg with PSS occlusion; in all 10 dogs, the increase in portal pressure was greater than 8 mm Hg. There were no intraoperative complications, and, after creation of the portocaval shunt, the intrahepatic PSS could be completely ligated in 8 of 10 dogs. The final portal pressure was 9 +/- 4 mm Hg. Postoperative complications included coagulopathy and death (1 dog), ascites (3 dogs), and incisional discharge (3 dogs). Five of 8 dogs had continued portosystemic shunting at 8 to 10 weeks after surgery. Multiple extrahepatic PSS were demonstrated in 4 of these dogs. Clinical outcome was excellent in all 9 surviving dogs. CONCLUSIONS AND CLINICAL SIGNIFICANCE: The surgical technique resulted in a high incidence of multiple extrahepatic PSS. Short-term clinical results were promising, but long-term outcome must be evaluated further.     

Intraoperative contrast echocardiography to verify the surgical occlusion of a single extrahepatic portosystemic shunt in a dog

This report details a bubble echocardiographic study carried out during the surgical treatment of a congenital single extrahepatic portosystemic shunt (PSS) in a Labrador Retriever. After celiotomy, agitated saline was injected through a jejunal vein and microbubbles appeared rapidly in the right cardiac chambers. The test confirmed the presence of a PSS, helping the surgeon to identify the vessel concerned and to rule out a second shunt. Successively, portography confirmed what the exploratory celiotomy had revealed before with the aid of the bubble study: a single shunt was located between the portal vein and the right renal vein. It was completely ligated, as all the criteria for this solution were met. Intraoperative contrast echocardiography (ICE) was easy to perform, helpful and undemanding. It is proposed here as an intraoperative ancillary test to diagnose all PSS and to confirm successful treatment when complete shunt closure is possible.     

Cerebrospinal fluid glutamine,tryptophan, and tryptophan metabolite concentrations in dogs with portosystemic shunts

OBJECTIVE: To determine whether glutamine (GLN), tryptophan (TRP), and tryptophan metabolite concentrations are higher in cerebralspinal fluid (CSF) dogs with naturally occurring portosystemic shunts (PSS), compared with control dogs. ANIMALS: 11 dogs with confirmed PSS and 12 control dogs fed low- and high-protein diets. PROCEDURE: Cerebrospinal fluid and blood samples were collected from all dogs. Serum and CSF concentrations of GLN, alanine, serine, TRP, 5-hydroxyindoleacetic acid (5-HIAA), and quinolinic acid (QUIN) were measured. RESULTS: Cerebrospinal fluid concentrations of GLN, TRP, and 5-HIAA were significantly higher in PSS dogs, compared with control dogs fed high- or low-protein diets. Cerebrospinal fluid QUIN concentration was significantly higher in PSS dogs, compared with control dogs fed the low-protein diet. Serum QUIN concentration was significantly lower in PSS dogs, compared with control dogs fed either high- or low-protein diets. CONCLUSIONS AND CLINICAL RELEVANCE: An increase in CNS GLN concentration is associated with high CSF concentrations of TRP and TRP metabolites in dogs with PSS. High CSF 5-HIAA concentrations indicate an increased flux of TRP through the CNS serotonin metabolic pathway, whereas high CSF QUIN concentrations indicate an increased metabolism of TRP through the indolamine-2,3-dioxygenase pathway. The high CSF QUIN concentrations in the face of low serum QUIN concentrations in dogs with PSS indicates that QUIN production from TRP is occurring in the CNS. High concentrations of QUIN and other TRP metabolites in the CNS may contribute to neurologic abnormalities found in dogs with PSS and hepatic encephalopathy.     

Evaluation of ameroid ring constrictors for the management of single extrahepatic portosystemic shunts in cats: 23 cases (1996-2001)

OBJECTIVE: To document the signalment; history; clinical signs; clinicopathologic, diagnostic imaging, and surgical findings; perioperative complications; and long-term clinical results of ameroid ring constrictor (ARC) placement on single extrahepatic portosystemic shunts (PSS) in cats. DESIGN: Retrospective study. ANIMALS: 23 cats treated with an ARC on a single extrahepatic PSS. PROCEDURE: An ARC was placed surgically around the PSS. Portal pressure was measured prior to ARC placement, with complete temporary PSS occlusion, and after ARC placement. Cats were scheduled for recheck transcolonic portal scintigraphy 8 to 10 weeks after surgery. Follow-up information was obtained by telephone interview with the owners. RESULTS: An ARC was successfully placed in 22 of 23 cats. Intraoperative complications, consisting of PSS hemorrhage, occurred in 2 cats. Mean (+/- SD) portal pressure (n = 15) was 6.7+/-2.9 mm Hg before PSS manipulation, 18.6+/-7.7 mm Hg with complete temporary PSS occlusion, and 6.9+/-2.7 mm Hg after ARC placement. Postoperative complications developed in 77% (17 of 22) of cats after ARC placement, and included central blindness, hyperthermia, frantic behavior, and generalized motor seizures. Perioperative mortality rate was 4.3% (1 of 23). Persistent shunting was identified in 8 of 14 cats. Overall, 75% (15 of 20) of cats had an excellent long-term outcome. CONCLUSIONS AND CLINICAL RELEVANCE: Placement of an ARC on single extrahepatic PSS in cats resulted in low surgical complication and perioperative mortality rates, but most cats did have substantial postoperative complications. Persistent shunting was common, although many cats with persistent shunting were clinically normal.