Cellophane banding of congenital intrahepatic portosystemic shunts in two Irish wolfhounds

Two three-month-old, male Irish wolfhound siblings were diagnosed with breed-typical left divisional congenital intrahepatic portosystemic shunts consistent with patent ductus venosus. The shunts were amenable to surgical dissection at a posthepatic location. Both dogs had cellophane banding for shunt attenuation. One dog was euthanased after developing post-ligation neurological dysfunction, which was refractory to treatment. The other dog survived and demonstrated shunt attenuation. Successful surgical management using cellophane banding of a patent ductus venosus has not been previously described in a large-breed dog.     

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.     

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.     

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.     

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.     

Clinical manifestations of cataracts in small breed dogs

Objective  To determine the incidence, etiology, and concurrent ophthalmic findings in small breed dogs that presented with cataracts.
Animal studied  Five hundred and sixty-one small breed dogs (942 eyes) were presented to the Veterinary Medical Teaching Hospital of Seoul National University between July 2002 and December 2007 with cataract.
Procedure  The medical records of small breed dogs with cataract were reviewed. The reason for presentation, cataract duration, bilaterality, breed, gender, age, vision, etiology, stage of cataract development, concurrent ophthalmic findings, IOP, ocular ultrasonography findings, and scotopic electroretinography (ERG) findings were investigated.
Results  The most frequently presented breeds were the Miniature/Toy Poodle ( n  = 112, 20.0%), Yorkshire Terrier ( n  = 110, 19.6%), and Shih Tzu ( n  = 95, 16.9%). The Miniature/Toy Poodle showed a significantly higher odds ratio for cataract formation (2.6). The proportion of female cataract patients was significantly higher than that of male cataract patients in the overall population ( P  < 0.05). The Miniature/Toy Poodles had significantly higher numbers of females affected with cataract ( P  < 0.01). The mean age for cataract formation was 8.3 ± 3.9 years. The mean age at onset in the Miniature/Toy Poodle and Yorkshire Terrier was significantly higher, whereas that in the Miniature Schnauzer group was significantly lower ( P  < 0.0001). Clinical signs related to lens induced uveitis had a tendency to increase with cataract progression ( P  < 0.05). There were no significant differences in the b-wave amplitude for mixed rod cone response by stage ( P  = 0.137).
Conclusions  Small breed dogs with cataracts had characteristics with regard to age of onset and gender distribution, depending on the breed.     

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.     

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.     

Use of portocaval venografts with ameroid constrictor placement and hepatic lobectomy for treatment of intralobular intrahepatic portocaval shunts in four dogs

Liver lobectomy for complete attenuation of intrahepatic portosystemic shunts appears to be a safe and effective surgical treatment. When the intrahepatic shunt vessel can be definitively palpated within a liver lobe or its presence confirmed portographically, liver lobectomy represents a technically simple and effective method of complete shunt attenuation. To maintain portal pressure at an acceptable value after lobectomy, an extrahepatic portocaval shunt vessel can be created by use of an external jugular vein graft. A second shunt vessel can be created if portal pressure remains increased after placement of 1 shunt. Gradual and safe attenuation of the shunt vessel is achieved by placement of an ameroid constrictor on the extrahepatic graft at the time of the initial surgery.     

Breed distribution of dogs with diabetes mellitus admitted to a tertiary care facility

OBJECTIVE: To determine which dog breeds are at low and high risk for developing diabetes mellitus (DM). DESIGN: Cohort study. ANIMALS: Hospital population of 221 dogs with DM and 42,882 dogs without DM during 5.5 years. PROCEDURE: 165 breeds (including a mixed-breed category) were represented in the hospital population. Breed-specific expected numbers of dogs with DM were calculated by multiplying the proportion of all dogs admitted to the hospital that were determined to have DM during the study period by the breed-specific totals during the study period. Breeds or breed groups evaluated in the analysis (n = 20) were restricted to those that had a combined observed and expected count > 5 to document breeds at low and high risk for developing DM. Proportionate changes in the risk of developing DM by breed were calculated and presented using exact odds ratios, 95% confidence intervals, and P values. Mixed-breed dogs were chosen as the reference breed. RESULTS: Samoyeds, Miniature Schnauzers, Miniature Poodles, Pugs, and Toy Poodles were at high risk for developing DM. Dog breeds found to be at low risk for developing DM were German Shepherd Dog, Golden Retriever, and American Pit Bull Terrier. CONCLUSION AND CLINICAL RELEVANCE: The finding that certain dog breeds are at low or high risk for developing DM suggests that some genetic defects may predispose dogs to development of DM, whereas other genetic factors may protect dogs from development of DM.     

Three hundred and three dogs with cataracts seen in Rio de Janeiro, Brazil

Objective  To describe the most common canine breeds affected with cataracts in Rio de Janeiro.
Animals  Three hundred and three dogs were included in this retrospective study. Animal ages ranged from 6 months to 14.8 years.
Material and methods  All records of dogs seen by the Ophthalmology Service of Policlínica Veterinária Botafogo between January 2005 and June 2008 were reviewed. Animals with cataracts were separated, and breed and age were evaluated.
Results  Most of the dogs presented with cataracts were Toy Poodles with a mean age of 8.2 years, followed by Cocker Spaniels and Bichon Frises. The percentage of Toy Poodles affected with cataracts was 13.8% while 33.3% of Bichon Frise was diagnosed with cataracts.
Conclusions  Toy Poodles are a popular breed in Rio de Janeiro. Without regulations on breeding, the prevalence of cataracts may increase rapidly. Furthermore, due to the relatively late onset of cataract formation in the Toy Poodle (mean 8.2 years of age), affected animals may have produced several litters of puppies. This study emphasizes the importance of screening for the presence of inherited ocular abnormalities such as cataracts prior to breeding.     

Congenital portosystemic shunts in Maltese and Australian Cattle Dogs

SUMMARY Congenital portosystemic shunts were definitively diagnosed in 62 dogs over a period of 15 years. Maltese and Australian Cattle Dogs were significantly over-represented, accounting for 14 and 13 cases, respectively. Maltese invariably had a single extrahepatic shunt derived from the left gastric or gastrosplenic vein, whereas Cattle Dogs usually had large intrahepatic shunts involving the right liver lobes. The clinical syndromes resulting from anomalous portosystemic communications were indistinguishable in the 2 breeds. Fasting blood ammonia concentration was elevated in 20 of 22 dogs tested, providing a minimally invasive and effective means of diagnosis. Complete or partial shunt attenuation was performed successfully in all 9 Maltese and in 2 of 6 Cattle Dogs in which it was attempted.     

Partial versus Complete Attenuation of Single Portosystemic Shunts

Twenty-two dogs with congenital single portosystemic shunts were treated by partial or complete ligation of the shunts. Intraoperative portal pressures before and after shunt ligation, and central venous pressures measured after 3 minutes of temporary shunt occlusion, were evaluated prospectively. Portal pressures after ligation, increases in portal pressure above baseline values, and decreases in central venous pressure during temporary occlusion were significantly greater in dogs that underwent partial portosystemic shunt ligation and in dogs that developed postoperative complications. Absence of arborizing intrahepatic vasculature in intraoperative mesenteric portograms did not indicate whether partial or complete shunt attenuation could be performed safely, but it was correlated with greater occurrence of post-operative complications.     

Congenital portosystemic shunts in dogs and cats

Congenital portosystemic shunts (PPS) are abnormal vascular communications that allow blood from the intestine to bypass the liver, and are classified as intrahepatic or extrahepatic. Clinical signs are generally related to the nervous, gastrointestinal or urinary systems, and are often vague. In addition, changes present on routine blood analysis are often mild and non-specific. For this reason, alternative tests are required for a diagnosis. Diagnostic tests include serum bile-acid concentrations, ammonia tolerance test, portography, ultrasonography and/or scintigraphy. Medical therapy involves reducing absorption of encephalopathic toxins from the gastrointestinal tract and may prolong survival. Surgical therapy is aimed at attenuation of the shunting vessel and provides improved survival rates. The traditional approach has been complete or partial ligation of the shunt. More recent approaches have involved slow, progressive attenuation with ameroid constrictors or cellophane banding. Overall, prognosis following surgical therapy is good in dogs and fair in cats.     

Surgical Management of Multiple Congenital Intrahepatic Shunts in Two Dogs

Objective —To present details of an unusual type of portosystemic shunt and its surgical management in two dogs.
Animals —Two young dogs that had a tentative diagnosis of a portosystemic shunt on the basis of clinical signs and serum biochemical abnormalities. Abdominal ultrasonography and contrast portography demonstrated multiple intrahepatic shunts. In both cases, the multiple shunts arose from a single branch of the portal vein.
Outcome—It was possible to locate and attenuate flow through the shunts via a transportal venotomy under conditions of hepatic vascular occlusion. Clinical and biochemical abnormalities resolved after surgery in both dogs. Postoperative sonography revealed complete obliteration of the shunt plexus in one of the dogs.     

Generalized motor seizures after portosystemic shunt ligation in dogs: five cases (1981-1988)

Severe generalized motor seizures developed in 5 dogs between 13 hours and 3 days after surgical attenuation of a single extrahepatic portosystemic shunt. Three dogs died, and a fourth was euthanatized because of poor prognosis for recovery. The fifth dog, although improved, was still not clinically normal 15 months after surgery. An intra-or extracranial cause for the seizures could not be identified in any of these dogs. Postmortem examination results in 3 dogs were similar to findings previously reported in dogs with portosystemic shunts, but which did not undergo surgical shunt ligation. Of the 5 dogs, 4 were greater than 18 months old, which may indicate that older dogs are more likely to develop seizures after shunt ligation than are younger dogs.     

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.     

Homozygosity of single nucleotide polymorphisms in the 3′ region of the canine estrogen receptor 1 gene is greater in Toy Poodles than in Miniature Dachshunds and Chihuahuas

Differences in the distribution of single nucleotide polymorphisms (SNPs) and haplotypes in the estrogen receptor α gene (ESR1) were examined in Miniature Dachshunds (n = 48), Chihuahuas (n = 20) and Toy Poodles (n = 18). Five DNA fragments located in the 40‐kb region at the 3′ end of ESR1 were amplified by polymerase chain reaction and were directly sequenced. We compared allele, genotype and estimated haplotype frequencies at each SNP in the 3′ end of ESR1 for these three breeds of small dog. The frequency of the major allele and the genotype frequency of the major allele homozygotes, were significantly higher in Toy Poodles for five SNPs (SNP #5, #14–17) than in Miniature Dachshunds, and significantly higher in Toy Poodles than Chihuahuas for three SNPs (SNP #15–17). A common haplotype block was identified in an approximately 20‐kb region encompassing four SNPs (SNPs # 14–17). The frequencies of the most abundant estimated haplotype (GTTG) and GTTG homozygotes were significantly higher in Toy Poodles than in the other two breeds. These results imply that homozygosity for the allele, genotype and haplotype distribution within the block at the 3′ end of ESR1 is greater in Toy Poodles than in Miniature Dachshunds and Chihuahuas.     

Experimental evaluation of four methods of progressive venous attenuation in dogs

OBJECTIVE: To determine the most effective and reliable method for progressive attenuation of single extrahepatic portosystemic shunts in dogs. STUDY DESIGN: The effects of the four treatments on femoral vein diameter and histology were compared with controls. ANIMALS: Fourteen healthy adult dogs. METHODS: Twenty-eight canine femoral veins were subjected to sham surgery (4), partial attenuation using silk (5), cellophane banding (6), ameroid constrictor implantation (5), and intravascular thrombogenic coils (8). Changes in vein diameter were evaluated at weekly intervals using venography. After 6 weeks, the dogs were humanely euthanatized, and histopathology was performed on the femoral veins. RESULTS: Only cellophane and ameroid constrictors produced progressive and permanent vein attenuation. Ameroid constrictors produced complete occlusion within 14 days in four of five veins and by 21 days in the fifth vein. Cellophane banding produced slow progressive (but not complete) attenuation in five of six veins. Complete occlusion was demonstrated in four of eight veins after thrombogenic coil implantation; however, recanalization occurred in all but one dog. Perivascular silk did not produce significant progressive attenuation. CONCLUSIONS: Ameroid constrictors produced rapid occlusion of femoral veins. Cellophane banding resulted in slower attenuation. Thrombogenic coils produced attenuation, but this was not sustained in many cases. Silk did not promote ongoing attenuation. CLINICAL RELEVANCE: Both ameroid constrictor implantation and cellophane banding show promise for progressive attenuation of single extrahepatic portosystemic shunts in dogs. Because rapid occlusion was seen with ameroid constrictors, however, cellophane banding maybe a safer technique in animals with increased hepatic vascular resistance. Further evaluation of both treatments in clinical cases is warranted.