Shunts In Dogs Research Articles

Long‐term outcome after surgical ameroid ring constrictor placement for treatment of single extrahepatic portosystemic shunts in dogs

To report long-term clinical outcome in dogs treated for single congenital extrahepatic portosystemic shunt (CEHPSS) with a ameroid ring constrictor (ARC) and to identify perioperative variables associated with outcome. Retrospective, multi-institutional study. Dogs (n = 206) with CEHPSS. Medical records of dogs with CEHPSS treated by ARC were reviewed for perioperative and short-term (<1 month) data. Long-term follow-up information was obtained by telephone interview with referring veterinarians and/or owners. Kaplan-Meier analysis was used to estimate median survival time. Factors associated with short-term survival, outcome grade, and total survival time were identified. Fifteen dogs died <1 month after ARC placement. Follow-up data were obtained for 112 of 191 dogs that survived >1 month; median follow was 54 months (range, 1-175 months) and 103 (92%) dogs had no clinical signs. Estimated median survival time was 152 months. Variables significantly associated with short-term survival included being intact and a low total white blood cell (WBC) count. Variables significantly associated with a successful outcome included having surgery later in the study period and negative postoperative nuclear scintigraphy. In the long-term survival analyses, intact dogs and those with higher WBC counts and occlusion pressures and lower bile acid concentrations were more likely to survive. Dogs with CEHPSS treated by ARC generally have a good prognosis and prolonged postoperative survival.

Intrahepatic portocaval shunt in dogs: diagnostic approach and therapy

Portosystemic shunt (PSS) is a relatively common phenomenon in dogs. PSS may be either intrahepatic (IHPSS) or extraheptic (EHPSS), congenital or acquired. The most commonly identified shunts are of congenital origin and consist of single, large intrahepatic or extrahepatic shunts. Since the discovery of the condition, PSS has been treated by medical or surgical methods, or a combination of both. Surgical techniques for partial attenuation of EHPSS and IHPSS include silk suture attenuation, ameroid constrictor placement, cellophane banding, and hydraulic occluders. This article describes the diagnostic process and the treatment of a case of IHPSS in a 7-month-old male entire Bull Mastiff, and provides an in depth discussion regarding clinical and diagnostic features, surgical treatment, complications, follow-up and prognostic factors.

Portacaval Shunt Established in Six Dogs Using Magnetic Compression Technique

Background and AimsInstalling the transjugular intrahepatic portosystemic shunt for portal hypertension is relatively safe, but complications are still high. To explore a new method of portacaval shunt, the magnetic compression technique was introduced into the shunting procedure.MethodsA portal-inferior vena cava shunt was performed on 6 male mongrel dogs by two hemocompatible Nd-Fe-B permanent magnets, parent and daughter. The parent magnet was applied to the inferior vena cava guided by a catheter through the femoral vein. The daughter magnet was moved to the anastomosis position on the portal vein with a balloon catheter through the splenic vein. After the daughter magnet reached the target position, the two magnets acted to compress the vessel wall and hold it in place. Five to 7 days later, under X-ray guidance, the magnets were detached from the vessel wall with a rosch-uchida transjugular liver access set. One month later, histological analysis and portal venography were performed.Results5-7 days after the first surgery, a mild intimal hyperplasia in the portal vein and the inferior vena cava, and continuity of the vascular adventitia from the portal vein to the inferior vena cava as observed. During the second surgery, the contrast media could be observed flowing from the portal vein into the inferior vena cava. Portal venography revealed that the portosystemic shunt was still present one month after the second surgery.ConclusionsMagnamosis via a device of novel design was successfully used to establish a portacaval shunt in dogs.

More answers needed on congenital portosystemic shunts in dogs and cats

Veterinary RecordVolume 172, Issue 14 p. 360-361 Research More answers needed on congenital portosystemic shunts in dogs and cats Adrian W. Philbey BVSc, PhD, MANZCVSc, MRCVS, Corresponding Author Adrian W....

Serum gastrin concentrations in dogs with liver disorders

Dogs with liver disorders often display gastrointestinal signs that may be triggered by ulceration. The liver is important for inactivation of some forms of gastrin. Therefore, hypergastrinaemia has been implicated...

Prevalence of Patent Foramen Ovale with Right‐to‐Left Shunting in Dogs with Pulmonic Stenosis

Right-to-left (R-L) shunt caused by patent foramen ovale (PFO) concurrent with pulmonic stenosis (PS) is considered common, although there is a lack of published evidence. To investigate the prevalence of R-L shunt caused by a PFO in dogs with PS. Thirty-one client-owned dogs with PS, without obvious extracardiac disease detected on the clinical examinations. Case control study: R-L shunt probably caused by PFO was diagnosed when IV injected microbubbles appeared at the left atrial level with an intact atrial septum on echocardiography (bubble-positive dogs). The severity of PS concurrent tricuspid regurgitation (TR), relative thickness of the right ventricle, and relative right atrial area were compared between bubble-positive and bubble-negative dogs. The prevalence of R-L shunts caused by PFO was 39% (12 of 31 cases). The instantaneous pressure gradient (PG) across the pulmonic valve and relative thickness of the right ventricle were significantly increased in bubble-positive compared with those in bubble-negative dogs. None of the dogs with mild or moderate PS (pressure gradient < 80 mm Hg, n = 2) demonstrated R-L shunt. The prevalence of TR in bubble-positive dogs was significantly higher than that in bubble-negative dogs. DISCUSSION AND CLINICAL RELEVANCE: Patent foramen ovale PFO with R-L shunt was more common in dogs with very severe PS and absent in dogs with mild PS.

Treatment of extrahepatic congenital portosystemic shunts in dogs – what is the evidence base?

A variety of surgical treatments and medical therapies are recommended for dogs with extrahepatic congenital portosystemic shunts (CPSS). The objective of this review was to assess the evidence base for the management of extrahepatic CPSS in dogs. An online bibliographic search was performed in November 2010 to identify articles relating to the question "Which of the treatment options for extrahepatic CPSS in dogs offers the best short- and long-term outcomes?" Articles were assigned a level of evidence based on a modified grading system. Thirty-eight articles were included in the review. Thirty-six articles were classified as grade 4 and two as grade 5. The timings and methods of assessment of short- and long-term outcomes varied widely between studies. One prospective study (grade 4a) showed that surgically treated dogs survived significantly longer than medically treated dogs. Four retrospective studies (grade 4b) compared the outcome of two surgical techniques but there were no statistically significant differences between treatment groups in terms of complications or outcome. The review found that the evidence base for the treatment of extrahepatic CPSS is weak. There is a lack of evidence of short- and long-term outcomes to recommend one treatment over another.

Inherited liver shunts in dogs elucidate pathways regulating embryonic development and clinical disorders of the portal vein

Congenital disorders of the hepatic portal vasculature are rare in man but occur frequently in certain dog breeds. In dogs, there are two main subtypes: intrahepatic portosystemic shunts, which are considered to stem from defective closure of the embryonic ductus venosus, and extrahepatic shunts, which connect the splanchnic vascular system with the vena cava or vena azygos. Both subtypes result in nearly complete bypass of the liver by the portal blood flow. In both subtypes the development of the smaller branches of the portal vein tree in the liver is impaired and terminal branches delivering portal blood to the liver lobules are often lacking. The clinical signs are due to poor liver growth, development, and function. Patency of the ductus venosus seems to be a digenic trait in Irish wolfhounds, whereas Cairn terriers with extrahepatic portosystemic shunts display a more complex inheritance. The genes involved in these disorders cannot be identified with the sporadic human cases, but in dogs, the genome-wide study of the extrahepatic form is at an advanced stage. The canine disease may lead to the identification of novel genes and pathways cooperating in growth and development of the hepatic portal vein tree. The same pathways likely regulate the development of the vascular system of regenerating livers during liver diseases such as hepatitis and cirrhosis. Therefore, the identification of these molecular pathways may provide a basis for future proregenerative intervention.

Use of aDacron Shape‐Memory Intravascular Coil to Achieve Slow, Progressive Occlusion of the Jugular Vein in Dogs

To investigate the ability of shape memory Dacron polymer vascular coils to induce the complete, gradual occlusion of the canine jugular vein. Observational pilot study. Nine purpose-bred dogs. Eighteen coils were deployed in nine dogs using fluoroscopic-guided percutaneous transvenous coil implantation. Individual coil formulations varied around a Dacron polymer base. Jugular vein diameter, percent vessel occlusion, and thrombus echogenicity were monitored at weekly intervals using ultrasonography. Affected jugular veins were harvested at 6 weeks post-implantation and histopathological analysis was performed to assess adventitial fibrosis, intimal layer thickening, and inflammation. Ten coils migrated from the jugular veins to the pulmonary vasculature within 0-2 weeks following implantation. Three jugular veins achieved at least 90% occlusion at six weeks. Histopathology of these jugular veins revealed marked perivascular thickening and fibrovascular proliferation, increased infiltration of macrophages, neutrophils and lymphocytes, and abundant fibroplasia. Complete, gradual occlusion of a jugular vein was achieved in three dogs. Significant vessel wall reaction and inflammation can induce gradual vessel occlusion when a Dacron coil remains implanted within the jugular vein. Dacron polymer coils could be a feasible treatment option for the gradual occlusion of congenital portosystemic shunts in dogs using minimally invasive, percutaneous transvenous implantation.

Hepatic gene expression and plasma albumin concentration related to outcome after attenuation of a congenital portosystemic shunt in dogs

In dogs with a congenital portosystemic shunt (CPSS), the outcome after CPSS attenuation is difficult to predict but is most likely related to hepatic and vascular proliferation that follows the attenuation. The aim of this study was to evaluate the prognostic value of shunt localization (extrahepatic vs. intrahepatic), plasma albumin concentration and hepatic mRNA expression of 19 genes involved in hepatic and vascular growth. The study population consisted of 48 dogs that were referred for surgical ligation of a single intrahepatic or extrahepatic CPSS. Gene expression was measured in intraoperatively sampled hepatic tissue with quantitative real-time PCR. Albumin, methionine adenosyltransferase 2α (MAT2α) and HGF activator (HGFac) were positively associated with complete recovery after CPSS attenuation using multivariate statistical analyses. Individual outcome could be correctly predicted in 83% of dogs using albumin, MAT2α and HGFac as high or low values compared to cut-off values of 19.5 g/L, 0.457 and 0.974, respectively. These variables predicted outcome after CPSS ligation better than shunt localization or albumin alone. Other evaluated gene products were not correlated with outcome.

Treatment of Hydrocephalus with Ventriculoperitoneal Shunting in Twelve Dogs

To report use of ventriculoperitoneal shunt in dogs for management of hydrocephalus for which no cause could be identified. Case series. Dogs with hydrocephalus (n=12). Medical records (June 2003-June 2009) were reviewed to determine preoperative clinical findings, initial postoperative, and long-term outcome. Additional follow-up information was obtained from owners and referring veterinarians. All dogs had signs of forebrain dysfunction, 7 had vestibular signs and 3 had signs of spinal pain. Postoperative complications included pain (n=4), undershunting because of shunt kinking (n=1) and seizures (n=1). Initial improvement occurred in all dogs and was sustained in 9 dogs, 1 of which required revision surgery. Sustained clinical improvement can be achieved in hydrocephalus with no active underlying cause by use of ventriculoperitoneal shunting.

Not hearing is believing: novel insight into cardiopulmonary function using agitated contrast and ultrasound

the advancement of science depends heavily on the development and successful application of new techniques. Progress in ultrasound technology has allowed researchers in physiology to examine many important parameters noninvasively, including cerebral blood flow velocity, pulmonary artery systolic

Intravascular Occlusion for the Correction of Extrahepatic Portosystemic Shunts in Dogs

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. Use of an intravascular occlusion device can effectively and safely result in acute complete occlusion of EHPSS in dogs. Seven dogs with naturally occurring EHPSS that presented to the Purdue University Veterinary Teaching Hospital. 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). 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. 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.

Sensitivity and specificity of fasting ammonia and serum bile acids in the diagnosis of portosystemic shunts in dogs and cats

Portosystemic shunt (PSS) is the most common cause of hepatic encephalopathy in dogs and cats. Fasting ammonia and serum bile acids (SBA) are used to diagnose PSS, but their true sensitivity and specificity have not been fully evaluated, especially in cats. The purpose of this study was to determine the diagnostic accuracy of fasting ammonia and SBA concentrations in the diagnosis of PSS in dogs and cats and to compare diagnostic accuracy between species. A retrospective analysis of data from 373 dogs and 85 cats presented to the clinic from 1996 to 2006 was carried out. Based on clinical, laboratory, and imaging findings, animals were grouped as having PSS, parenchymal hepatic disease, or extrahepatic disease. The sensitivity and specificity of ammonia and SBA concentrations for the diagnosis of PSS were calculated and receiver-operating characteristic analysis was used to optimize cut-offs. Using the upper limit of laboratory reference intervals (ammonia, 59 micromol/L; SBA, 20 micromol/L), the sensitivity and specificity of ammonia was 85% and 86% in dogs, and 83% and 76% in cats, respectively. The sensitivity and specificity of SBA was 93% and 67% in dogs, and 100% and 71% in cats, respectively. Using optimal cut-off points for ammonia (dogs, 57 micromol/L; cats, 94 micromol/L) the sensitivity and specificity was 91% and 84% in dogs and 83% and 86% in cats, respectively. Using optimal cut-off points for SBA (dogs, 58 micromol/L; cats, 34 micromol/L) the sensitivity and specificity was 78% and 87% in dogs and 100% and 84% in cats. Increased fasting ammonia and SBA concentrations are accurate indicators of PSS. An improvement in diagnostic accuracy can be achieved by using defined optimal cut-off points for the selective diagnosis of PSS.

Rebuttal from Hopkins, Olfert, and Wagner

Rebuttal from Hopkins, Olfert, and Wagner

Comments on Point:Counterpoint: Exercise-induced intrapulmonary shunting is imaginary vs. real

Comments on Point:Counterpoint: Exercise-induced intrapulmonary shunting is imaginary vs. real

Evidence of Inheritance of Intrahepatic Portosystemic Shunts in Irish Wolfhounds

The etiogenesis of congenital portosystemic shunt in dogs is not understood. In Irish Wolfhounds, intrahepatic portosystemic shunt (IHPSS) is thought to be hereditary, but the mode of inheritance is unknown. To document the genetic background and investigate the potential mode of inheritance of IHPSS in Irish Wolfhounds. Three mature, privately owned, affected siblings and their progeny produced in 2 litters. Prospective, observational study. Two test matings of 1 affected sire with 2 of his affected sisters were used to determine the inheritance pattern. Affection status was determined by measuring venous blood ammonia concentrations, detection of the shunt by ultrasonography and confirmation during surgical attenuation of the intrahepatic shunting vessel. In 1 litter of 5 pups all had an IHPSS. In the other litter 5 of 11 pups were affected. Both left- and right-sided shunts occurred in both litters. No sex predisposition was evident among affected dogs. Our results show that IHPSS in Irish Wolfhounds is a familial disorder that is likely genetic. It is unlikely that the mode of inheritance is monogenic. A digenic, triallelic trait could explain the observed occurrence of IHPSS but other modes of inheritance cannot be excluded.

Scintigraphic Diagnosis of Portosystemic Shunts

Portal scintigraphy is a quick noninvasive method to the diagnosis of portosystemic shunts in dogs and cats. Scintigraphic procedures have evolved over the past 25 years. Currently, trans-splenic portal scintigraphy is the preferred method. High quality studies can be obtained with small radiopharmaceutical doses.

Point:Counterpoint: Exercise-induced intrapulmonary shunting is imaginary vs. real

Pulmonary gas exchange efficiency deteriorates with exercise in both humans and other species, increasing the alveolar-arterial PO2 difference (AaDO2) ([2][1]). The potential contributors to this are ventilation-perfusion inequality, alveolar-capillary diffusion limitation, and shunt ([20][2]).

Liver Size, Bodyweight, and Tolerance to Acute Complete Occlusion of Congenital Extrahepatic Portosystemic Shunts in Dogs

To investigate the relationship between preoperative liver size, bodyweight, and tolerance to shunt occlusion in dogs with congenital extrahepatic portosystemic shunt(s) (CPSS). Longitudinal cohort study. Dogs with CPSS (n=35). Ultrasonography was used to measure preoperative maximum transverse dimension of the liver (TS) of each dog. Intraoperative portal pressures were measured, before and after CPSS occlusion, via a jejunal vein catheter. Tolerance to shunt occlusion was judged on gross visceral observations, and on changes in portal pressure, central venous and mean arterial pressures. TS was significantly related to bodyweight (P<.05). Mean ratios for TS/bodyweight were calculated for dogs tolerant and intolerant of acute complete shunt occlusion. Dogs tolerant to occlusion had significantly higher TS/bodyweight ratios than dogs intolerant to occlusion (P=.025). Dogs with a TS/bodyweight ratio of >7 were more likely to tolerate CPSS occlusion than dogs with a TS/bodyweight ratio of <5 (P=.036). A model was generated to predict portal pressure rise after shunt occlusion, based on liver dimensions and bodyweight (R=0.668). Intestinal oxygenation did not correlate significantly with tolerance to CPSS occlusion (P=.29). In dogs with CPSS, liver size (relative to bodyweight) is significantly greater (P=.025) in dogs that are tolerant of full ligation than intolerant of occlusion. Preoperative measurement of bodyweight and liver size help indicate the likelihood of tolerance to acute complete occlusion of CPSS in dogs.