Complete Ligation of Extrahepatic Congenital Portosystemi Shunts in Nonencephalopathic Dogs

Objective —To evaluate lack of encephalopathy as a positive prognostic factor for complete ligation of extrahepatic congenital portosystemic shunts in dogs.
Study Design —Retrospective analysis of case records.
Animals —Dogs with extrahepatic congenital portosystemic shunts treated at the Veterinary Medical Teaching Hospital of the College of Veterinary Medicine, Cornell University, from 1985 to 1996.
Methods —The ability to completely ligate the shunting vessel in 12 nonencephalopathic dogs was compared with that in 44 encephalopathic dogs with similar shunts.
Results —Clinical signs in the 12 nonencephalopathic dogs were related to ammonium biurate urolithiasis. All 12 dogs had single extrahepatic shunting vessels. The rate of complete ligation in the nonencephalopathic dogs was 92%, whereas the rate of complete ligation in the 44 encephalopathic dogs with single extrahepatic shunts was 59%. The ability to completely ligate the shunt in nonencephalopathic dogs was significantly better ( P = .04) than in the encephalopathic dogs.
Conclusion—Lack of encephalopathy is a positive prognostic factor for complete ligation of single extrahepatic congenital portosystemic shunts.
Clinical Relevance —In most affected dogs, extrahepatic congenital portosystemic shunts in nonencephalopathic dogs can be completely ligated.     

New perspectives on the development of extrahepatic portosystemic shunts

In this essay we use clinical evidence and knowledge of anatomy to examine the relationship between blood flow and formation of congenital extrahepatic portosystemic shunts in dogs and cats. First we report on the clinical findings in a series of 50 dogs and 10 cats and then systematically review peer‐reviewed data on the detailed anatomy of shunts in dogs and cats. In dogs four types of shunt: spleno‐caval, left gastro‐phrenic, left gastro‐azygos and those involving the right gastric vein account for 94% of extrahepatic shunts. Cats also exhibit four types of shunt: spleno‐caval, left gastrophrenic, left gastro‐caval and left gastro‐azygos, and the first three of these account for 92% shunts in this species. Our findings lead us to propose that preferential blood flow influences the subsequent formation of one of a number of defined and consistent congenital extrahepatic portosystemic shunts in dogs and cats.     

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.     

SIMULTANEOUS CONGENITAL AND ACQUIRED EXTRAHEPATIC PORTOSYSTEMIC SHUNTS IN TWO DOGS

Two dogs with simultaneous congenital and acquired portosystemic shunts are reported. The first dog was an eight-month-old, male Golden Retriever with a history of peritoneal effusion, polyuria/polydipsia, and stunted growth. The dog had a microcytic, hypochromic anemia, a mildly elevated AST, and a moderate to severely elevated preprandial and postprandial serum bile acids. Transcolonic portal scintigraphy confirmed the presence of a portosystemic shunt. An intraoperative mesenteric portogram was performed. Two conjoined congenital extrahepatic portosystemic shunts and multiple acquired extrahepatic portosystemic shunts were identified. The second dog was a five-month-old, mixed breed with two week history of peritoneal effusion. Abdominal ultrasound and transcolonic scintigraphy were used to diagnose a portosystemic shunt. A single extrahepatic portosystemic shunt, portal hypertension, and multiple acquired collateral shunts were identified at surgery. The histologic alterations observed in these dogs were consistent with a portosystemic shunt. In these dogs, the presence of congenital and acquired portosystemic shunts and histopathologic findings are considered to represent a combination of congenital portosystemic shunts and noncirrhotic portal hypertension or portal vein hypoplasia.     

Portosystemic shunts: A diagnostic challenge

The case report in this issue by Woodford et al. (2017) describes the surgical management of an extrahepatic portosystemic shunt in a 5‐week old miniature foal. Only a handful of reports exist in the literature describing surgical procedures for repair of these congenital abnormalities in foals. One of the important aspects of the accompanying case report was the multidisciplinary approach taken in handling, imaging and surgical repair of the extrahepatic shunt. Small animal internal medicine specialists and surgeons diagnose portosystemic shunts much more frequently than equine veterinarians, regardless of whether they are general practitioners or specialists. It is therefore important to work as a team with small and large animal practitioners. The case described by Woodford et al. (2017) had a positive outcome.     

Neurological dysfunction in three dogs and one cat following attenuation of intrahepatic portosystemic shunts

Neurological dysfunction is an uncommon complication following extrahepatic portosystemic shunt ligation. Three dogs and one cat are described that developed neurological signs within 21 to 42 hours of attenuation of intrahepatic portosystemic shunts. None of these cases had biochemical evidence of hepatic encephalopathy postoperatively. Two dogs died during management of status epilepticus following aspiration of food. One dog died six months postoperatively. The cat had persistent neurological dysfunction at discharge, but was alive and had recovered most of its neurological function at the time of writing, 37 months after surgery. This report demonstrates the potential for animals with intrahepatic portosystemic shunts to develop postoperative neurological signs and highlights the difficulty of managing such cases. Two dogs had both intrahepatic and extrahepatic portosystemic shunts. Large intestinal malrotation (partial situs inversus) may have been linked to the development of a portosystemic shunt in the remaining dog.     

ANATOMY OF EXTRAHEPATIC PORTOSYSTEMIC SHUNTS IN DOGS AS DETERMINED BY COMPUTED TOMOGRAPHY ANGIOGRAPHY

Congenital extrahepatic portosystemic shunts are anomalous vessels joining portal and systemic venous circulation. These shunts are often diagnosed sonographically, but computed tomography (CT) angiography produces high‐resolution images that give a more comprehensive overview of the abnormal portal anatomy. CT angiography was performed on 25 dogs subsequently proven to have an extrahepatic portosystemic shunt. The anatomy of each shunt and portal tributary vessels was assessed. Three‐dimensional images of each shunt type were created to aid understanding of shunt morphology. Maximal diameter of the extrahepatic portosystemic shunt and portal vein cranial and caudal to shunt origin was measured. Six general shunt types were identified: splenocaval, splenoazygos, splenophrenic, right gastric‐caval, right gastric‐caval with a caudal shunt loop, and right gastric‐azygos with a caudal shunt loop. Slight variations of tributary vessels were seen within some shunt classes, but were likely clinically insignificant. Two shunt types had large anastomosing loops whose identification would be important if surgical correction were attempted. A portal vein could not be identified cranial to the shunt origin in two dogs. In conclusion, CT angiography provides an excellent overview of extrahepatic portosystemic shunt anatomy, including small tributary vessels and loops. With minor variations, most canine extrahepatic portosystemic shunts will likely be one of six general morphologies.     

Effect of breed on anatomy of portosystemic shunts resulting from congenital diseases in dogs and cats: a review of 242 cases

OBJECTIVE: To evaluate the effect of species and breed on the anatomy of portosystemic vascular anomalies in dogs and cats. DESIGN: Retrospective study of 233 dogs and nine cats presenting to the University Veterinary Centre, Sydney. METHODS: Case records were evaluated for breed, sex, age, anatomical and histological diagnosis. Cases were included when a portosystemic vascular anomaly resulted from a congenital or developmental abnormality of the liver or portal venous system. RESULTS: Disease conditions included single congenital portosystemic shunt with patent portal vasculature (214 dogs, nine cats), portal vein aplasia (nine dogs), multiple acquired shunts resulting from portal vein hypoplasia (seven dogs), biliary atresia (one dog) and microvascular dysplasia (one dog). One Maltese had a single, congenital shunt and multiple acquired shunts resulting from hepatic cirrhosis. Breeds that were significantly over-represented included the Maltese, Silky Terrier, Australian Cattle Dog, Bichon Frise, Shih Tzu, Miniature Schnauzer, Border Collie, Jack Russell Terrier, Irish Wolfhound and Himalayan cat. Bichon Frise with shunts were significantly more likely to be female than male (12:2, P < 0.001). Two hundred and fourteen dogs (91.4%), and all cats, had shunts that were amenable to attenuation. Inoperable shunts occurred in 19 dogs (8.2%). Fifty six of 61 (92%) operable shunts in large breed dogs were intrahepatic, versus 10/153 (7%) in small breeds (P < 0.0001). Breeds that were not predisposed to portosystemic shunts were significantly more likely to have unusual or inoperable shunts than dogs from predisposed breeds (29% versus 7.6%, P < 0.0001). No significant relationship between breed and shunt type could be determined in cats. CONCLUSION: Breed has a significant influence on shunt anatomy in dogs. Animals presenting with signs of portosystemic shunting may suffer from a wide range of operable or inoperable conditions. Veterinarians should be aware that unusual or inoperable shunts are much more likely to occur in breeds that are not predisposed to congenital portosystemic shunts.     

Use of transcolonic portal scintigraphy to evaluate efficacy of cellophane banding of congenital extrahepatic portosystemic shunts in 16 dogs

OBJECTIVE: To evaluate the efficacy of cellophane banding of single congenital extrahepatic portosystemic shunts in dogs using transcolonic portal scintigraphy. To investigate the portal circulation of those dogs with elevated postoperative shunt fractions to determine the cause of the persistent shunting. Further, to evaluate whether presenting signs, clinical pathology findings and liver histopathology are predictive of outcome. DESIGN: Prospective study of 16 dogs presenting with single congenital extrahepatic portosystemic shunts. PROCEDURE: Dogs with single extrahepatic portosystemic shunts attenuated by cellophane banding underwent portal scintigraphy and bile acids tolerance testing pre- and post-operatively. Dogs identified with elevated shunt fractions at 10 weeks post-operatively underwent mesenteric portovenography. Qualitative hepatic histopathology from all dogs was reviewed by a veterinary pathologist and assigned a semi-quantitative score to identify any abnormalities that may predict surgical outcome. RESULTS: At 10 weeks post cellophane banding, 10 of 16 cases (63%) had normal shunt fractions, whilst six dogs (37%) had increased shunt fractions and seven dogs (44%) had increased serum bile acids. Of these dogs, mesenteric portovenography revealed incomplete closure of the shunt in three dogs (18.6%) and multiple acquired shunts in three dogs (18.6%). Liver histopathology findings were similar for all dogs, regardless of outcome. CONCLUSIONS: Cellophane banding is an efficacious method for complete gradual occlusion of single extrahepatic shunts when the shunt vessel is attenuated to < or = 3 mm. Transcolonic portal scintigraphy is a reliable method for assessment of shunt attenuation and, unlike serum bile acids, is not influenced by other causes of liver dysfunction.     

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.     

Congenital portosystemic shunts in toy and miniature poodles

Three male Poodles (two Toy, one Miniature) were presented to their veterinarians for evaluation of urolithiasis and varying degrees of hepatic encephalopathy. All three dogs were diagnosed as having intrahepatic shunts and referred for surgical correction. In each case, shunts arose from the right branch of the portal vein and were amenable to perivascular dissection caudal to where the vessel entered the hepatic parenchyma and to placement of perivascular cellophane bands to achieve shunt attenuation. During the same period, a female Miniature Poodle also presented for treatment of a congenital portosystemic shunt discovered during evaluation for generalised motor seizures. This animal had an extrahepatic portoazygous shunt that was completely ligated. Congenital portosystemic shunts have not previously been identified in Toy and Miniature Poodles at the University Veterinary Centre, Sydney and the anatomical types of shunt seen in this breed have not previously been reported in a consecutive series of cases. The three male dogs are noteworthy for a number of reasons: all had intrahepatic shunts, despite being small breed dogs; all three presented in a similar fashion, and all had shunts of an anatomical type amenable to placement of cellophane bands. One male dog died within 12 hours of surgery, the remaining three dogs survived and their liver function was normal at follow-up between 2 and 3 months after surgery. Use of cellophane bands for successful attenuation of intrahepatic shunts has not been previously reported.     

Transvenous coil embolisation for the treatment of single congenital portosystemic shunts in six dogs

This article describes the treatment of single congenital portosystemic shunts (CPSs) (intrahepatic and extrahepatic) using an interventional radiology technique involving embolisation of anomalous vessels with percutaneous coils. Briefly, a multipurpose catheter was introduced into the caudal vena cava and then into the portosystemic shunt. An autoexpandable stent was placed in the caudal vena cava, next to the shunt, in order to avoid coil migrations, and a cobra-like vascular catheter was used to pass through the stent and to place the coils in the shunt. This technique was used for treatment of CPS in six dogs. The results indicate that percutaneous embolisation of a CPS using coils, a less invasive technique than the traditional surgical technique, may result in complete closure of the anomalous vessel without development of portal hypertension.     

Outcomes of cellophane banding for congenital portosystemic shunts in 106 dogs and 5 cats

OBJECTIVE : To report outcomes after cellophane banding of single congenital portosystemic shunts in dogs and cats. STUDY DESIGN : Retrospective study of sequential cases. ANIMALS : One hundred and six dogs and five cats. METHODS : Medical records were reviewed for breed, sex, age at surgery, shunt anatomy, results of pre- and postoperative biochemical analysis, development of postligation neurologic dysfunction, portal hypertension or other serious complications, and the owners' perception of their animal's response to surgery. RESULTS : Ninety-five dogs and all 5 cats had extrahepatic shunts. Eleven dogs had intrahepatic shunts. Six dogs (5.5%) died as a result of surgery from portal hypertension (2 dogs), postligation neurologic dysfunction (2), splenic hemorrhage (1) and suspected narcotic overdose (1). Serious complications were more common in dogs with intrahepatic shunts than those with extrahepatic shunts (P=.002). Postligation neurologic dysfunction necessitated treatment in 10 dogs and 1 cat; 8 dogs and the cat survived. Clinical signs attributed to portosystemic shunting resolved or were substantially attenuated in all survivors. Postoperative serum bile acid concentrations or results of ammonia tolerance testing were available for 88 animals; 74 (84%) were normal and 14 (16%) were abnormal. Multiple acquired shunts were documented in two animals. CONCLUSIONS : Cellophane banding is a safe and effective alternative to other methods of attenuation. CLINICAL RELEVANCE : Slow occlusion of portosystemic shunts using a variety of methods is being evaluated world wide. Cellophane banding is a relatively simple procedure with comparable safety and efficacy to previously reported techniques.     

Intravascular Occlusion for the Correction of Extrahepatic Portosystemic Shunts in Dogs

Background: Congential extrahepatic portosystemic shunts (EHPSS) are common in dogs. An effective minimally invasive technique for correction of EHPSS could result in reduced morbidity, reduced costs, and reduced hospitalization times. Hypothesis: Use of an intravascular occlusion device can effectively and safely result in acute complete occlusion of EHPSS in dogs. Animals: Seven dogs with naturally occurring EHPSS that presented to the Purdue University Veterinary Teaching Hospital. Methods: Prospective, clinical trial. The 7 dogs were consecutively enrolled over a 2‐year period. Results of serum biochemistry, total serum bile acids, fasting plasma ammonia, abdominal radiography, and ultrasonography suggested the diagnosis of portosystemic shunts in all dogs. Definitive diagnosis of EHPSS was achieved with cranial mesenteric arterial portography and acute occlusion was attempted by the deployment of the Amplatzer vascular plug (AVP). Results: EHPSS were identified in all dogs consisting of 5 portocaval and 2 portoazygous variants; 1/7 dogs (14%) were intolerant to temporary complete occlusion of the EHPSS. Of the remaining 6 dogs, 5 (83%) had complete occlusion of the EHPSS by the AVP. There were no complications and resolution of abnormal clinical signs and laboratory values was achieved in 4/5 (80%) dogs with complete occlusion. Conclusions and Clinical Importance: Intravascular correction of EHPSS by the AVP is a viable option to surgical correction while larger studies will be required to determine the clinical applicability of this procedure in the broader portosystemic shunt population.     

The creation of an international audit and database of equine colic surgery: survey of attitudes of surgeons

REASONS FOR PERFORMING STUDY: Currently, there is a lack of available evidence-based data concerning the optimum treatments for horses affected by different types of colic and this precludes the application of clinical audit in this area. In order to accumulate such data, a large-scale, multicentre database of the outcomes of colic surgery is proposed. The attitudes of surgeons is an important consideration in determining the feasibility of developing this database. OBJECTIVES: To assess attitudes and opinions of equine surgeons concerning clinical audit and to assess the perceived advantages and problems of setting up a large-scale international audit/database of colic surgery. METHODS: Interviews were conducted with 30 equine surgeons (large animal/equine surgeons who are diplomates of either the American College of Veterinary Surgeons or the European College of Veterinary Surgeons). Questionnaires were sent by e-mail to 98 equine surgeons. RESULTS: Face to face interviews were conducted (n = 30) and 43/98 completed questionnaires received (44%). The results of the 2 techniques were very similar. There was generally a high level of interest in the development of a large scale database of colic surgery, but perceived problems included time to collect and submit data, and confidentiality issues. A minority of surgeons reported that they were undertaking any form of specific monitoring of the results of colic surgery within their hospitals. CONCLUSIONS: There is a good level of interest among equine surgeons to develop a large scale database of colic surgery and most would be willing to contribute data from their own hospitals provided that data collection is quick and easy, and that confidentiality is maintained.     

Partial anomalous pulmonary venous connection with portosystemic shunt in a cat

A nine-month-old castrated male domestic shorthair presented for evaluation with a three-month history of hematuria. Portosystemic shunts and calculi within the bladder were suspected, and computed tomography angiography was performed. Computed tomography angiography identified an extrahepatic portosystemic shunt and a partial anomalous pulmonary venous connection, with the lobar vein of the right caudal lobe draining into the caudal vena cava. After anesthesia was administered to the cat, tachypnea and wheezing respiratory sounds were observed, and thoracic radiography revealed the right middle lung lobe atelectasis and an unstructured interstitial pattern in the left cranial lobe. Echocardiography showed left and right atrial enlargement and slight interventricular septal flattening in diastole. Based on these findings, cardiogenic pulmonary edema was suspected, and the cat was treated with furosemide. The clinical symptoms were resolved the next day. Closure of the extrahepatic portosystemic shunt was performed on days 47 and 157. Left atrial enlargement and interventricular septal flattening were attenuated after the procedure. At the time of writing this report (seventeen months after diagnosis), the cat exhibited no clinical signs, but subjective right atrial enlargement remained at approximately the same level. This report represents the first case of a partial anomalous pulmonary venous connection and a portosystemic shunt in a cat.     

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.     

Lack of consensus on consensual response

The pupillary light reflex (PLR) is a routinely utilized clinical test to quickly assess integrity of subcortical light perception pathways in patients. While interpretation is simple for ophthalmologists, interestingly discrepancy occurs in annotation of the test results, especially for the consensual response. An email survey sent to diplomates of either the American or European Colleges of Veterinary Ophthalmologists (ACVO and ECVO, respectively), requesting use of a ‘direct/consensual’ annotation convention, showed 58% of respondents preferred one convention while 39% preferred a different convention. The majority preferred convention was different between ACVO and ECVO respondents. Standardization of PLR annotation convention across specialists is recommended for clarity in medical record keeping and communication among colleagues.     

Outcomes after extrahepatic portosystemic shunt ligation in 49 dogs

OBJECTIVE: To evaluate outcomes after attenuation of extrahepatic portosystemic shunts in dogs using surgical silk. DESIGN: Retrospective study. PROCEDURE: Case records were reviewed for degree of surgical attenuation, experience of the primary surgeon, perioperative mortality and problems related to persistent portosystemic shunting or shunt ligation. Presence of portosystemic shunting after surgery was evaluated by ammonia tolerance testing, measurement of postprandial serum bile acid, plasma urea and cholesterol concentrations and liver enzyme activity. The influence of age, postocclusion portal pressure, primary surgeon, degree of attenuation and postoperative biochemical findings on the occurrence of postoperative problems was assessed. RESULTS: The mortality rate was 2.1%. Shunt attenuation was complete in 34% and partial in 66% of dogs. Portal hypertension necessitating ligature removal was encountered in only one dog. Five dogs experienced neurological abnormalities (seizures or ataxia), possibly as a manifestation of 'postligation seizure syndrome'. Postoperative liver function was normal in 78% of dogs, including 70% with partial shunt attenuation. Experience of the surgeon was related positively to outcome after partial attenuation (P = 0.002). Postoperative biochemical evidence of abnormal liver function was the most sensitive predictor of recurrence of clinical signs referable to persistent portosystemic shunting. CONCLUSIONS: In the hands of an experienced surgeon, surgical attenuation of single extrahepatic shunts was safe and effective, even in animals with partial attenuation. Most dogs with biochemical evidence of persistent shunting suffer relapse of clinical signs within 18 months of surgery. Postligation neurological syndromes of variable intensity may be more common than previously thought.     

Cellophane banding for the gradual attenuation of single extrahepatic portosystemic shunts in eleven dogs

Objective To evaluate the efficacy and short term effects of a cellophane banding technique for progressive attenuation of canine single extrahepatic portosystemic shunts.
Design A prospective trial of 11 dogs with single congenital extrahepatic shunts.
Procedure Rectal ammonia tolerance testing and routine biochemical tests were performed preoperatively on all dogs. In seven dogs, preoperative abdominal Doppler ultrasonography was also performed. Exploratory laparotomy revealed a single extrahepatic portocaval shunt in each animal, which was attenuated using a cellophane band with an internal diameter of 2 to 3 mm. The abdomen was closed routinely. Follow-up biochemical analysis and abdominal Doppler ultrasonography or splenoportography were performed postoperatively.
Results The shunt was not amenable to total ligation in 11 dogs, based upon reported criteria. All dogs recovered uneventfully from surgery without evidence of portal hypertension, and showed clinical improvement thereafter. Shunt occlusion was deemed to have occurred in 10 dogs based on resolution of biochemical and/or sonographic abnormalities. One dog continued to have sonographic evidence of portosystemic shunting when evaluated 3 weeks after surgery, despite normal ammonia tolerance, but was lost to subsequent follow-up. Two dogs, in which 3 mm cellophane bands were placed, experienced delayed shunt occlusion.
Conclusion Cellophane banding is simple to perform, and causes progressive attenuation of single extrahepatic shunts in dogs. Further work is needed to determine the maximum diameter of a cellophane band which will produce total attenuation, and the long-term safety and reliability of the treatment.