Hepatic microvascular dysplasia in dogs: a retrospective study of 24 cases (1987-1995)

Jejunal arteriovenous malformation and multiple acquired extrahepatic portosystemic shunts in a juvenile dog, presenting with melena

A juvenile dog referred with a 1-month history of persistent melena and severe anaemia, was diagnosed with a jejunal arteriovenous malformation, and multiple acquired extrahepatic portosystemic shunts. A midline coeliotomy was performed, the jejunal arteriovenous malformation was localised intraoperatively and was successfully removed via an enterectomy. Histopathology confirmed a true arteriovenous malformation. Despite the initial improvement, the patient developed seizure episodes secondary to hepatic encephalopathy 8 months after surgery. Fifteen months after surgery, the owner opted for euthanasia due to the ongoing seizure episodes. Post-mortem histologic examination of the liver showed features consistent with portal vein hypoplasia. A congenital arteriovenous malformation should be considered as a differential diagnosis in juvenile patients with a chronic history of haemorrhage from the gastrointestinal tract. In addition, acquired portosystemic shunts may occur in patients with portal vein hypoplasia and jejunal arteriovenous malformations.

Congenital Portosystemic Shunts in Dogs and Cats: Classification, Pathophysiology, Clinical Presentation and Diagnosis

Congenital portosystemic shunts (CPSS) are abnormal vascular communications between the portal and the systemic circulation, bypassing the hepatic parenchyma and resulting in liver hypoplasia and hepatic insufficiency. Such connections develop in utero and persist postnatally. CPSS are among the two most common congenital vascular anomalies of the liver in small animals, along with primary hypoplasia of the portal vein without portal hypertension (PHPV without PH). CPSS can be extrahepatic (ECPSS), most commonly diagnosed in small and toy breed dogs and cats, or intrahepatic (ICPSS), most commonly seen in large breed dogs. Single ECPSS is the most common type encountered in both dogs and cats. Clinical signs of CPSS are non-specific and may wax and wane, while laboratory findings can raise clinical suspicion for CPSS, but they are also not specific. Definitive diagnosis will be established by evaluation of liver function tests, such as determination of fasting plasma ammonia (FA) levels, and pre- and postprandial serum bile acids concentrations, and diagnostic imaging. The purpose of this article is to review the definition, classification, pathogenesis, clinical presentation, and diagnosis of CPSS in dogs and cats, highlighted by the authors' clinical experience.

Diagnostic value of liver function tests and ultrasonography in dogs with suspected congenital portosystemic shunts

BACKGROUND

Diagnosing a congenital portosystemic shunt (cPSS) in dogs can be challenging. The current study aims to report diagnostic performance of fasting ammonia (FA), preprandial, postprandial and paired serum bile acids (SBA) and abdominal ultrasound (aUS) in dogs suspected of having a cPSS.

METHODS

Medical records of dogs suspected of having a cPSS at initial presentation were retrospectively reviewed.

RESULTS

In total, 192 dogs suspected of cPSS were included: a cPSS was confirmed in 147 dogs and excluded in 45 dogs. FA had the best combined sensitivity and specificity (77.4 and 93.3%, respectively) to diagnose cPSS. The sensitivity and negative predictive value were 100.0% for paired SBA, making paired SBA the best test to exclude cPSS in this population. Sensitivity and specificity of aUS were 80.8 and 90.0%, respectively.

CONCLUSIONS

In dogs with clinical signs compatible with cPSS, elevated FA is suggestive of cPSS, whereas normal paired SBA makes the presence of a cPSS unlikely. Although aUS is a useful tool to diagnose cPSS, additional imaging is required to visualize cPSS in almost 20% of cases. Furthermore, the localisation of cPSS can be misdiagnosed, especially in case of extrahepatic cPSS that do not insert into the prehepatic vena cava.

Serum insulin-like growth factor-1 as a marker of improved liver function and surgical outcome in dogs with congenital extrahepatic portosystemic shunts

Serum insulin-like growth factor-1 concentration (sIGF-1c) is reduced in various hepatopathies in humans and dogs. This work aimed to evaluate sIGF-1c in dogs before and after congenital extrahepatic portosystemic shunt (cEHPSS) attenuation, in relation to surgical outcome (closed vs. persistent shunting). Secondarily, it aimed to assess if sIGF-1c can discriminate between cEHPSS and portal vein hypoplasia (PVH) and finally compare sIGF-1c ratio (postoperative/preoperative sIGF-1c) to pre-prandial serum bile acids (preBA), post-prandial bile acids (postBA), bile acid stimulation test (BAST) and fasting ammonia (FA), regarding surgical outcome. Thirty-nine dogs were included: 15 with closed cEHPSS, 15 with persistent shunting and nine with PVH. Transplenic portal scintigraphy was used to classifiy surgical outcome. There was no significant difference in sIGF-1c between dogs with cEHPSS and those with PVH (P > 0.05). Postoperative sIGF-1c increased in all dogs (P < 0.001 and P = 0.023 for closed and persistent shunting, respectively) and the increase was more pronounced in closed cEHPSS than in persistent shunting (P = 0.006). Using an optimal sIGF-1c ratio cut-off of 2.23, the sensitivity was 93.3% and the specificity was 66.7% for differentiation between surgical outcomes. Serum pre-prandial bile acids, postBA BAST and FA had sensitivities of 80%, 86.7%, 86.7%, 60%; and specificities of 100%, 93.3%, 93.3%, 100%, respectively. There was a greater increase in sIGF-1c after shunt closure than during persistent shunting; nevertheless sIGF-1c ratio was inferior to advanced imaging to assess surgical outcome.

Lobular diameters of autopsied dog livers give clues for an appropriate liver biopsy methodology

Hepatobiliary diseases of animals are frequently diagnosed by a combination of imaging, clinical pathology, and histopathology. A standardized surgical liver biopsy protocol, however, has not been established in veterinary medicine with regard to the selection of lobe and site of the liver to yield the most diagnostic information. To address this matter, we histologically examined 33 livers of autopsied dogs from which tissue samples of 4 different lobes as well as 4 different sites of each lobe were prepared. We measured the hepatic lobular diameter (HLD) as an objective variable to refer to the inter-lobar or inter-site difference among the biopsied samples. A measurement of 2,623 hepatic lobules resulted in 1.042 mm as the average of all the HLD values. Statistical analysis further revealed that the HLD tended to be small in a superficial 2 mm area of the liver parenchyma regardless of biopsy location, thus this area should be evaluated carefully by pathologists. The results also suggest that the HLD values of the quadrate lobe may measure smaller than those in the other lobes. Therefore, one would be able to obtain representative data of the entire liver by taking a sample from any single lobe except for the quadrate lobe. HLD measurements are needed in order to accumulate potentially useful information on the microanatomy and pathophysiology of the liver.

Retrospective Liver Histomorphological Analysis in Dogs in Instances of Clinical Suspicion of Congenital Portosystemic Shunt

Introduction

The clinical symptoms of portosystemic shunts (PSSs) and hepatic microvascular dysplasia (HMD) - portal vein hypoplasia (PVH) in dogs are similar. PSSs are abnormal vascular connections between the portal vein system and systemic veins. HMD is a very rare developmental vascular anomaly, recognisable during histopathological examination. The study aim was to assess the prevalence of HMD-PVH and hepatocellular and vascular pathologies in the liver.

Material and Methods

Liver biopsies from 140 dogs (of different breeds and both sexes) arousing clinical suspicion of PSS were examined histopathologically.

Results

An initial PSS diagnosis was confirmed in 125 dogs (89.29%). HMD-PVH was found in 12.32% of dogs, as an isolated disease in 9.29%, especially in Yorkshire terriers, and with extrahepatic PSS in 6.67%. Histopathological analysis of muscles around sublobular veins showed that HMD cases presented hypertrophy or hypertrophy with fibrosis. In 2.17% of all dogs with liver vascular developmental disorders calcification was visible around vessels (without correlation by degenerative changes in those vessels), suggesting prior onset of deep metabolic disorders. Clinical suspicion of PSS was also formed upon quite different pathological processes in young dogs.

Conclusion

Histopathological findings diagnosed the type of vascular anomalies (PSS or HMD-PVH) or other pathological changes conclusively, therefore detailed hepatic histopathology is an indispensable component of the clinical diagnostic process.

Anomalies of the Portal Venous System in Dogs and Cats as Seen on Multidetector-Row Computed Tomography: An Overview and Systematization Proposal

This article offers an overview of congenital and acquired vascular anomalies involving the portal venous system in dogs and cats, as determined by multidetector-row computed tomography angiography. Congenital absence of the portal vein, portal vein hypoplasia, portal vein thrombosis and portal collaterals are described. Portal collaterals are further discussed as high- and low-flow connections and categorized in hepatic arterioportal malformation, arteriovenous fistula, end-to-side and side-to-side congenital portosystemic shunts, acquired portosystemic shunts, cavoportal and porto-portal collaterals. Knowledge of different portal system anomalies helps understand the underlying physiopathological mechanism and is essential for surgical and interventional approaches.

Multiple acquired portosystemic shunts secondary to primary hypoplasia of the portal vein in a cat

A 6-year 5-month-old spayed female Scottish Fold cat presented with a one-month history of gait abnormalities, increased salivation, and decreased activity. A blood test showed hyperammonemia and increased serum bile acids. Imaging tests revealed multiple shunt vessels indicating acquired portosystemic shunt. Histopathologic analysis of liver biopsy showed features consistent with liver hypoperfusion, such as a barely recognizable portal vein, increased numbers of small arterioles, and diffuse vacuolar degeneration of hepatocytes. These findings supported the diagnosis of primary hypoplasia of the portal vein/microvascular dysplasia, (PHPV/MVD). To our knowledge, this is the first case of feline PHPV/MVD that developed multiple acquired portosystemic shunts and presented with hepatic encephalopathy.

Gallbladder Agenesis in 17 Dogs: 2006-2016

Background

Gallbladder agenesis (GBA) is extremely rare in dogs.

Hypothesis/Objectives

To describe the history, clinical signs, diagnosis, treatment, and outcomes of dogs with GBA.

Animals

Seventeen client‐owned dogs with GBA.

Methods

Medical records from 2006 through 2016 were retrospectively reviewed. Dogs were included when GBA was suspected on abdominal ultrasonography and confirmed by gross evaluation. Signalment, clinical signs, clinicopathological data, diagnostic imaging, histopathology, treatment, and outcome were recorded.

Results

Dogs were of 6 different breeds, and Chihuahuas (10 of 17) were most common. Median age at presentation was 1.9 (range, 0.7–7.4) years. Clinical signs included vomiting (5 of 17), anorexia (2 of 17), ascites (2 of 17), diarrhea (1 of 17), lethargy (1 of 17), and seizures (1 of 17). All dogs had increased serum activity of at least 1 liver enzyme, most commonly alanine aminotransferase (15 of 17). Fifteen dogs underwent computed tomography (CT) cholangiography; common bile duct (CBD) dilatation was confirmed in 12, without evidence of bile duct obstruction. Gross evaluation confirmed malformation of the liver lobes in 14 of 17 dogs and acquired portosystemic collaterals in 5 of 17. Ductal plate malformation was confirmed histologically in 16 of 17 dogs. During follow‐up (range, 4–3,379 days), 16 of 17 dogs remained alive.

Conclusions and Clinical Importance

Dogs with GBA exhibit clinicopathological signs of hepatobiliary injury and hepatic histopathological changes consistent with a ductal plate abnormality. Computed tomography cholangiography was superior to ultrasound examination in identifying accompanying nonobstructive CBD distention. Computed tomography cholangiography combined with laparoscopic liver biopsy is the preferable approach to characterize the full disease spectrum accompanying GBA in dogs.

Clinicopathological Findings and Prognosis in Canine Cases Diagnosed As Primary Hypoplasia of the Portal Vein

Canine primary hypoplasia of the portal vein (PHPV) is a microscopic malformation of the hepatic vasculature. The prevalence, clinical signs, and clinicopathological findings of PHPV in dogs are unclear, because there are few reports concerning PHPV in the veterinary literature. This retrospective study reviewed clinical records and liver biopsy data from 48 dogs with hepatic disease that were examined at a private veterinary hospital in Japan between April 2011 and March 2014 to determine the prevalence of PHPV among dogs that underwent liver biopsy and to determine the clinical and clinicopathological findings of PHPV in dogs. Records for all 48 dogs that underwent liver biopsy were investigated. Collected data included signalment, clinical signs, physical examination findings, complete blood cell count, chemistry results, pre-and postprandial serum total bile acid concentrations, coagulation profiles (prothrombin time, activated partial thromboplastin time, fibrinogen, and antithrombin), and abdominal ultrasonography findings at the first medical examination. The diagnosis of PHPV was made on the basis of histological examination of hepatic biopsy specimens and portography or CT angiography. Among the 48 canine cases, 28 dogs (58.3%) were diagnosed with PHPV, which was the most common diagnosis. The most frequent clinical sign in dogs with PHPV was asymptomatic persistently increased liver enzymes (57.1%). Toy poodles were at a significantly higher risk of PHPV than other breeds among dogs that underwent liver biopsy (P < 0.001). The median survival time of dogs with PHPV was more than 5 years. Plasma fibrinogen concentration below the reference range was an indicator of PHPV in this study. Dogs with PHPV frequently had mild clinical signs and a favorable prognosis.

Canine Breed-Specific Hepatopathies

Canine hepatopathies, both congenital and acquired, arise from an interaction between genes and environment. Many show increased breed prevalences. This article reviews the current understanding on breed predispositions for congenital portosystemic shunts; microvascular dysplasia and portal vein hypoplasia; ductal plate abnormalities (congenital hepatic fibrosis and Caroli disease); chronic hepatitis (both copper associated and idiopathic); vacuolar hepatopathies; and gallbladder mucocele. Although all these diseases can occur in many breeds and crossbreeds, understanding breed predispositions helps recognition and will guide future research to improve understanding of causes and treatments.

Emphysematous pyonephrosis associated with extrahepatic portosystemic shunt in a dog

A 16-month-old intact female Maltese dog was referred for examination of depression and vomiting. Ultrasonography revealed dilated right renal pelvis containing echogenic fluid with free gas. A hyperechoic material suspected of urolith was identified in the right ureter. Computed tomography revealed emphysematous change of the right kidney associated with ureteral obstruction and extrahepatic portosystemic shunt (EHPSS). Ureteronephrectomy and surgical correction were performed for the EHPSS. Escherichia coli was isolated from pus from the right kidney. Quantitative analysis revealed that the urolith was an ammonium urate stone. After 5 months follow-up, no complication was observed. This is the first report of emphysematous pyonephrosis associated with EHPSS in a dog.

Evaluation of a semiquantitative SNAP test for measurement of bile acids in dogs

Background. Serum bile acids (SBA) are used as a routine screening tool of liver function in dogs. Serum samples are usually shipped to a referral laboratory for quantitative analysis with an enzymatic chemistry analyzer. The canine SNAP Bile Acids Test (SNAP-BAT) provides an immediate, semi-quantitative measurement of bile acid concentrations in-house. With the SNAP-BAT, bile acids concentrations of 5–30 µmol/L are quantified, and results outside of that range are classified as <5 or >30 µmol/L. Agreement of the SNAP-BAT with the enzymatic method has not been extensively investigated.

Objectives. The purposes of this prospective clinical study were to assess the precision of the SNAP-BAT and determine agreement of SNAP-BAT with results from an in-house chemistry analyzer.

Methods. After verifying intra-assay precision of the SNAP-BAT, a prospective analysis was performed using blood samples collected from 56 dogs suspected to have liver disease. Each sample was analyzed with an enzymatic, in-house chemistry analyzer and the SNAP-BAT. Agreement between the two methods was statistically assessed using the κ index of agreement.

Results. Intra-assay variability was minimal. The κ index for agreement between the SNAP-BAT and routine chemistry analyzer was between 0.752 and 0.819, indicating substantial to near perfect agreement.

Conclusions. The SNAP-BAT is a highly accurate, semi-quantitative test that yields immediate results, and has very little intra-assay variability, particularly for results >30 µmol/L.

The inheritance of extra-hepatic portosystemic shunts and elevated bile acid concentrations in Maltese dogs

OBJECTIVES

To determine the heritability of extra-hepatic portosystemic shunts and elevated post-prandial serum bile acid concentrations in Maltese dogs.

MATERIALS AND METHODS

Maltese dogs were recruited and investigated by a variable combination of procedures including dynamic bile acid testing, rectal ammonia tolerance testing, ultrasonography, portal venography, surgical inspection or necropsy. In addition, nine test matings were carried out between affected and affected dogs, and affected and unaffected dogs.

RESULTS

In 135 variably related Maltese, shunt status could be confirmed in 113, including 19 with an extra-hepatic portosystemic shunt (17 confirmed at surgery, 2 at necropsy). Rectal ammonia tolerance testing results and post-prandial serum bile acid concentrations were retrievable for 50 and 88 dogs, respectively. Pedigree information was available for these 135 and an additional 164 related dogs. Two consecutive test matings were carried out between two affected animals (whose shunts had been attenuated), with 2 of 8 (25%) of offspring having an extra-hepatic portosystemic shunt. Six test matings were carried out between an affected and an unaffected animal, with 2 of 22 (9%) offspring affected. Heritability of extra-hepatic portosystemic shunt was 0·61 calculated using variance components analysis [95% confidence interval (CI) 0·14 to 1·0, P=0·001]. The best fitting model from segregation analysis was a common, partially penetrant, recessive model (allele frequency 0·34, penetrance 0·99, CI 0·09 to 1·0). The heritability of elevated post-prandial serum bile acid (and thus likely portal vein hypoplasia) was 0·81 (CI 0·43 to 1·0, P=0·2) after logarithmic transformation of post-prandial serum bile acid concentrations.

CLINICAL SIGNIFICANCE

There is strong support for extra-hepatic portosystemic shunts and elevated post-prandial serum bile acid concentrations both being inherited conditions in Maltese.

Comparison of 99mTcO4(-) trans-splenic portal scintigraphy with per-rectal portal scintigraphy for diagnosis of portosystemic shunts in dogs

OBJECTIVE

To evaluate trans-splenic portal scintigraphy (TSPS) and per-rectal portal scintigraphy (PRPS) for diagnosis of congenital portosystemic shunts (CPSS) in dogs, and compare these results with surgical findings.

STUDY DESIGN

Prospective, randomized cross over clinical trial.

ANIMALS

Dogs (n=42) with suspected CPSS.

METHODS

Dogs had TSPS and PRPS 48 hours apart; quantity of radionuclide administered was recorded. Three independent, blinded reviewers evaluated each scintigraphic study for study quality, shunt presence, number, and location of shunt termination (caudal vena cava, azygos vein). All dogs had exploratory celiotomy. Negative scintigraphic findings were confirmed with intraoperative mesenteric portography. Ameroid constrictors were placed on all extrahepatic CPSS, and hepatic biopsies were obtained.

RESULTS

TSPS was 100% sensitive and specific for diagnosis of CPSS and significantly (P<.05) more likely than PRPS to detect shunt number and termination. Interpretation was consistent between observers, and TSPS required significantly less radionuclide than PRPS.

CONCLUSION

TSPS was as sensitive as PRPS for detection of shunting vessels, and consistently yielded studies of higher quality, allowing detection of shunt number and location with consistent interpretation among radiologists.

CLINICAL RELEVANCE

TSPS provides information about shunt number and location, which allows improved surgical planning. Because it requires significantly less radionuclide, TSPS improves safety, allows for more comprehensive patient care, and earlier surgical intervention.

The sonographic search for portosystemic shunts

The diagnostic investigation of portosystemic shunts (PSS) has evolved over the last few decades, helping to understand and identify these vascular anomalies that affect many dogs and cats. Ultrasonography has become an important tool in small animals and high-resolution systems are now widely available. Several sonographic features are observed with the different types of congenital and acquired PSS. A systematic, stepwise approach is described to facilitate ultrasound diagnosis of PSS in small animals.

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 findings in dogs with hyperammonemia: 90 cases (2000–2002)

OBJECTIVE

To determine ultrasonographic abnormalities in dogs with hyperammonemia.

DESIGN

Retrospective study.

ANIMALS

90 client-owned dogs with hyperammonemia.

PROCEDURE

Ultrasonography of the abdominal vessels and organs was performed in a systematic way. Dogs in which the ultrasonographic diagnosis was a congenital portosystemic shunt were included only if they underwent laparotomy or necropsy. Dogs in which the abdominal vasculature appeared normal and dogs in which the ultrasonographic diagnosis was acquired portosystemic shunts and portal hypertension were included only if liver biopsy specimens were submitted for histologic examination.

RESULTS

Ultrasonography excluded portosystemic shunting in 11 dogs. Acquired portosystemic shunts were found in 17 dogs, of which 3 had arterioportal fistulae and 14 had other hepatic abnormalities. Congenital portosystemic shunts were found in 61 dogs, of which 19 had intrahepatic shunts and 42 had extrahepatic shunts. Intrahepatic shunts originated from the left portal branch in 14 dogs and the right portal branch in 5. Extrahepatic shunts originated from the splenic vein, the right gastric vein, or both and entered the caudal vena cava or the thorax. Ultrasonography revealed splenic-caval shunts in 24 dogs, right gastric-caval shunts in 9 dogs, splenic-azygos shunts in 8 dogs, and a right gastric-azygos shunt in 1 dog.

CONCLUSIONS AND CLINICAL RELEVANCE

Results suggest that ultrasonography is a reliable diagnostic method to noninvasively characterize the underlying disease in dogs with hyperammonemia. A dilated left testicular or ovarian vein was a reliable indicator of acquired portosystemic shunts.

Diagnostic imaging of congenital porto-systemic shunts in dogs and cats: a review

An overview of clinical, laboratory, and diagnostic imaging features of congenital porto-systemic shunt (PSS) in dogs and cats is presented through the analysis of recent literature, and personal case log. Particular emphasis is given to diagnostic accuracy of ultrasonographic examination of PSS in the evaluation of shunt vessel anatomy, and of ancillary findings such as abnormalities of portal vein flow, portal branches, and liver size. Operative mesenteric portography to obtain information on PSS morphology and position, and quantitative hepatic scintigraphy, which allows the calculation of shunt fractions, are also described. Limitations for each diagnostic imaging technique are given.

Outcome of ameroid constrictor occlusion of single congenital extrahepatic portosystemic shunts in cats: 12 cases (1993-2000)

OBJECTIVE

To determine postoperative (< or = 6 days), short-term (< or = 90 days), and long-term (> or = 6 months) outcomes of cats undergoing ameroid constrictor occlusion of single congenital extrahepatic portosystemic shunts (PSS) and identify factors associated with outcome.

DESIGN

Retrospective study.

ANIMALS

12 cats.

PROCEDURE

Cats with single congenital PSS that underwent surgical placement of ameroid constrictors were identified. Follow-up information was obtained through telephone interviews and facsimile correspondence with referring veterinarians and owners. Results-All cats survived the surgery and were discharged from the hospital. One cat had seizures during the postoperative period. Five cats were clinically normal during follow-up evaluations within 90 days after the surgery. Long-term follow-up information was available for 9 cats. Three were clinically normal, 4 had been euthanatized because of progressive neurologic disease, and 2 had neurologic abnormalities that could not be controlled with medication. Four of 7 cats with continued or recurrent neurologic abnormalities 1 or more months after surgery had normal scintigraphic or hepatic function test results 2 to 6 months after surgery.

CONCLUSIONS AND CLINICAL RELEVANCE

Results suggest that the long-term outcome of ameroid constrictor occlusion of PSS in cats is poor. Owners of older cats and cats with preexisting neurologic signs should be made aware of the potential for a poor outcome when considering surgical correction of this disease.