Status Epilepticus after Ligation of Portosystemic Shunts

Status epilepticus developed in four dogs, 2 to 3 days after ligation of an extrahepatic portosystemic shunt. Pentobarbital or phenobarbital intravenously was required to control seizure activity. Two dogs treated with phenobarbital recovered. Exacerbation of hepatic encephalopathy secondary to metabolic changes after surgery may be a cause of this syndrome. A treatment protocol for status epilepticus after ligation of a portosystemic shunt is proposed.     

Soy Protein Isolate versus Meat-Based Low-Protein Diet for Dogs with Congenital Portosystemic Shunts

Background: Both presurgical preparation and long-term support of nonoperable dogs with congenital portosystemic shunts (CPSS) require optimal dietary management. Studies suggested that protein source may play an important role, with vegetable and dairy protein sources having better effects on hepatic encephalopathy (HE) than meat proteins.
Objectives: Determine whether a low-protein test diet with soy as its main protein source results in better scores than a control diet with the same composition but with poultry as its main protein source in dogs with CPSS.
Methods: In a double-blind cross-over study, 16 dogs received each diet for 4 weeks. Dogs in group T first received the test diet and then the control diet, whereas dogs in group C were fed the diets in the opposite order. Different variables (body weight, body condition score, HE score, fecal score, CBC, plasma tests of liver function including NH₃, and coagulation tests) were measured at the start of the study and after completion of each diet.
Results: One-way repeated measures ANOVA was performed. Plasma NH₃ was significantly lower after the test diet than after the control diet. The test diet also resulted in significantly higher fibrinogen concentrations and lower prothrombin times. The HE score improved with both diets, with no significant difference between the 2 diets.
Conclusions: Both diets achieved a significant improvement in HE score. The influence of the soy-based diet on plasma NH₃ concentration and coagulation parameters suggests that such a diet decreases the risk for HE and gives better support of liver function.     

Transportal Approach for Attenuating Intrahepatic Portosystemic Shunts in Dogs

A novel surgical approach, using portal venotomy during total hepatic vascular occlusion, was used to locate and attenuate congenital intrahepatic portosystemic shunts in nine dogs. Shunt location was consistent with a persistent ductus venosus in only two dogs. In the remaining seven dogs the shunts were window-like orifices arising from either the left (two dogs) or right portal vein branch (five dogs) and communicating with the ipsilateral hepatic vein or caudal vena cava. The transportal approach using total hepatic vascular occlusion consistently provided good access to the portosystemic shunts, including those with window-like communications. A 7 to 16 minute period of total vascular occlusion was well-tolerated hemodynamically, with few intraoperative complications. Intrahepatic shunts were successfully attenuated in eight dogs, while one dog with portal atresia was euthanatized. The postoperative course was complicated by high protein pulmonary edema (one dog), an encapsulated biliary pseudocyst (one dog) and uncontrollable hemorrhage caused by an uncharacterized coagulopathy (one dog). Three dogs required a second operation to further attenuate their shunts. The clinical condition of all seven surviving dogs was improved after surgery.     

Hepatic Organelle Pathology in Dogs with Congenital Portosystemic Shunts

Diversion of portal blood in congenital portosystemic shunts (CPSS) results in liver atrophy and passage of toxins into the systemic circulation causing hepatic encephalopathy. In some dogs, there is indirect evidence for hepatic insufficiency, but histologic findings are equivocal. This study determined whether hepatocyte integrity in PSS is comprised at a subcellular level using analytical subcellular fractionation of liver biopsies. Six dogs with CPSS had hypoproteinemia (6/6), increased serum alkaline phosphatase (6/6) and alanine aminotransferase (4/6) activity, hypocholesterolemia (6/6), and decreased blood urea (2/6). Liver biopsy specimens had increased activities (mU/mg protein) of alkaline phosphatase (17.9 +/- 10.1; controls 5.1 +/- 5.3: P less than 0.01), but not of other plasma membrane enzymes. There were increased activities of endoplasmic reticular (neutral alpha-glucosidase: 1.67 +/- 0.7; controls 0.86 +/- 0.2: P less than 0.01) and lysosomal enzymes (N-acetyl-beta-glucosaminidase: 12.6 +/- 2.3; controls 6.24 +/- 2.7: P less than 0.01; alpha-mannosidase: 0.85 +/- 0.5; controls 0.39 +/- 0.3: P less than 0.05). Subcellular fractionation on reorientating sucrose density gradients showed a high-density peak of alkaline phosphatase suggestive of a specific increase in the biliary canalicular component of enzyme activity. Neutral alpha-glucosidase was shifted to denser fractions, indicative of an increase in the proportion of rough-to-smooth endoplasmic reticulum and consistent with enhanced synthesis of membranous enzymes. There was also evidence for increased fragility of intracellular organelles, particularly lysosomes. In contrast, histology showed either no abnormalities or minor degenerative changes compatible with hepatic underperfusion.(ABSTRACT TRUNCATED AT 250 WORDS)     

Whole Blood Manganese Concentrations in Dogs with Congenital Portosystemic Shunts

Background: Manganese (Mn) is an essential mineral that is a cofactor for many enzymes required in the synthesis of proteins, carbohydrates, and lipids. Because hepatic clearance is essential in Mn homeostasis, conditions in humans resulting in hepatic insufficiency including cirrhosis and both acquired and congenital portosystemic shunting have been reported to result in increased blood Mn concentrations and increased Mn content in the central nervous system. Because Mn toxicity causes neurologic disturbances, increased Mn concentrations have been implicated in the pathogenesis of hepatic encephalopathy.
Hypotheses: Dogs with congenital portosystemic shunts (cPSS) have significantly higher whole blood Mn concentrations than do healthy dogs or those with nonhepatic illnesses.
Animals: Eighteen dogs with cPSS, 26 dogs with nonhepatic illnesses, and 14 healthy dogs.
Methods: Whole blood Mn was measured by graphite furnace atomic absorption spectrometry. The diagnosis of cPSS was made by ultrasonography or during celiotomy either by visual inspection of a shunting vessel or portovenography.
Results: Dogs with a cPSS had significantly higher whole blood Mn concentrations than did healthy dogs and dogs with nonhepatic illnesses. Whole blood Mn concentrations were not significantly different between healthy dogs and dogs with nonhepatic illnesses.
Conclusion and Clinical Importance: Dogs with a cPSS have significantly increased whole blood Mn concentrations. Additional studies are warranted to investigate the role of Mn in cPSS-associated hepatic encephalopathy.     

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.     

Gradual Occlusion of Extrahepatic Portosystemic Shunts in Dogs and Cats Using the Ameroid Constrictor

Gradual occlusion of the splenic vein, using a specialized device (ameroid constrictor), was evaluated experimentally in three normal beagle dogs. Splenoportograms were used to verify that total occlusion of the splenic vein had occurred in all dogs within 4 to 5 weeks after application of the device. The ameroid constrictor (AC) was also evaluated as a method of gradual vascular occlusion in 12 dogs and two cats with single, extrahepatic, portosystemic shunts (PSS). Serum bile acid (SBA) concentrations were measured and portal scintigraphy (PS) was performed on all 14 animals preoperatively and 10, 20, 30, and 60 days postoperatively. Two dogs (14%) died from portal hypertension in the early postoperative period. One dog and one cat developed multiple acquired PSS, confirmed by mesenteric portography 90 days after the operation. Portal scintigraphy confirmed total occlusion of the primary shunt in the other 10 animals. Shunt fractions (SF), as measured by PS on postoperative days 30 and 60, declined significantly from preoperative values. Significant decreases were noted between preoperative and postoperative values for preprandial SBA on postoperative day 60 and for postprandial SBA on postoperative day 30. SBA concentrations did not correlate with SF. Based on this study, gradual vascular occlusion using the AC is recommended as a method for treatment of single, extrahepatic, PSS.     

Splanchnic Surface Oximetry during Experimental Portal Hypertension and Surgical Manipulation of Portosystemic Shunts in Dogs

Surface oxygen tension (PSO2) was measured in dogs during experimental manipulation of the portal vein and hepatic artery, and during surgery to correct portosystemic shunting. There was no alteration in PSO2 of liver, pancreas, duodenum, or jejunum during partial (50%) or complete reduction of hepatic artery flow. After 100% reduction in portal vein blood flow, PSO2 was lower in jejunum, duodenum, and liver. With 50% reduction in portal flow, PSO2 was significantly decreased only in jejunum. In six dogs with single extrahepatic shunts, there was a significant correlation between portal pressure and jejunal PSO2. It was concluded that measurement of visceral organ PSO2 represents an accurate noninvasive means of obtaining objective data on the effect of reduction in hepatic blood flow on perfusion of other select splanchnic organs.     

Endogenous Benzodiazepine Activity in the Peripheral and Portal Blood of Dogs With Congenital Portosystemic Shunts

Objective- The purpose of this study was to determine whether an endogenous benzodiazepine receptor ligand (EBZ) was present in the arterial and portal blood of dogs with congenital portosystemic shunts (CPSS).
Study Design- The presence or absence of an EBZ was determined by the collection of systemic and portal blood from dogs with CPSS.
Animals- Fifteen client-owned dogs with a confirmed CPSS. All dogs had historical signs compatible with hepatic encephalopathy. Eight healthy dogs were used as controls.
Methods- In all dogs, systemic blood samples were collected after they were anesthetized. Portal blood samples were collected intraoperatively. EBZ was measured by radioreceptor assay.
Results- In 10 of 15 dogs, the portal blood concentration of EBZ was significantly elevated compared with normal dogs (mean, 13.2 ±18.55 ng/mL). Five dogs had elevated systemic blood EBZ levels (mean, 8.2 ±16.08 ng/mL). Eleven of 15 dogs had a higher portal than systemic blood concentration of EBZ. In contrast, control dogs had extremely low EBZ concentrations detected in their portal blood (mean, 0.16 ±0.3 ng/mL) and systemic blood (0 ng/mL). The mean portal and systemic blood concentrations in dogs with CPSS were significantly greater than in control dogs ( P <.05).
Conclusions- Elevated blood levels of EBZ were found in dogs with CPSS. The portosystemic gradient noted in 11 dogs suggests the gastrointestinal tract as a possible source for the endogenous ligand.
Clinical Relevance- Generalized motor seizures have been reported in dogs after surgical correction of CPSS. If the presence of a CPSS results in stimulation of brain receptors for benzodiazepines, post-CPSS ligation seizures may result from a withdrawal of EBZ after ligation of the portosystemic shunt.     

A Method for Controlling Portal Pressure After Attenuation of Intrahepatic Portacaval Shunts

Two dogs had right divisional intrahepatic portacaval shunts within the right lateral lobe of the liver. In both dogs, an extrahepatic portacaval vascular anastomosis was created, using an autologous right external jugular vein graft. The intrahepatic shunts were completely attenuated using a prehepatic intravascular caval approach. The creation of the vascular graft allowed postattenuation rises in portal pressure to be controlled, preventing the development of life threatening portal hypertension. Both dogs recovered from the procedure. One dog is clinically normal and does not require medication (8 months postoperatively); the other dog was euthanatized 5 months after surgery because of renal failure. Scintigraphy studies, performed before surgery, showed significant shunting of portal blood away from the liver (shunt indices 65% and 59%), whereas, similar studies done 4 weeks afterwards showed almost normal portal blood flow (shunt indices 16% and 18%, respectively).     

Endotoxin Concentrations Measured by a Chromogenic Assay in Portal and Peripheral Venous Blood in Ten Dogs With Portosystemic Shunts

A chromogenic Limulus amebocyte lysate assay was used to measure portal and peripheral venous endotoxin concentrations in ten medically managed dogs undergoing surgery for correction of a single extrahepatic portosystemic shunt. In all dogs, both peripheral and portal venous blood samples were obtained at the time of surgical manipulation of the anomalous vessel. In six dogs, peripheral venous samples were obtained an average of 8.0 months after surgery. Five physically normal dogs without biochemical or histologic evidence of liver disease served as controls. Data analysis failed to demonstrate significant differences in peripheral and portal venous endotoxin concentrations between the control and study groups. Postoperatively five of six dogs showed a measurable reduction in peripheral venous endotoxin concentration over intraoperatively obtained values, but the differences were not statistically significant (P = 0.06). Based on results of this study it was concluded that systemic endotoxemia was not present in dogs with a single extrahepatic portosystemic shunt that were medically stable prior to surgery.     

Per Rectal Portal Scintigraphy Using 99mTechnetium Pertechnetate to Diagnose Portosystemic Shunts in Dogs and Cats

Per rectal portal scintigraphy using 99mTechnetium pertechnetate (99mTcO4-) was used to diagnose portosystemic shunts (PSS) before surgical confirmation in seven dogs and two cats. Shunt fractions, representing the percent of portal blood that bypasses the liver, were determined by computer analysis of the scintigraphic images. Animals with portosystemic shunts had a mean preoperative shunt fraction of 84.02% (n = 9). The mean postoperative shunt fraction in four animals was 58.22%. The mean shunt fraction in ten control dogs was 5.00%. Per rectal portal scintigraphy is an innovative, easily performed, inexpensive method to diagnose congenital portosystemic shunts in dogs and cats.     

Portosystemic communications: Follow-up of 32 cases

A multicentre retrospective study of dogs that underwent surgical attenuation of portosystemic communications (PSC) was conducted. These dogs were followed from three months after surgery to evaluate the long term effect of surgery on their life span, disease-free interval, and owner assessment of postoperative quality of life of the dogs. Seventy-five per cent of the dogs in this study had no long term postoperative recurrence of clinical signs. Of the 25 per cent of dogs that showed recurrent clinical signs, all but one had partial attenuation of the PSC. The location of the PSC was the only factor that correlated with whether the dogs were still alive. All owners were pleased with the postoperative quality of life of their dogs.     

Partial antagonization of midazolam-medetomidine-ketamine in cats--atipamezole versus combined atipamezole and flumazenil

Two different methods, administered both subcutaneously and intravenously, to reverse intramuscular midazolam-medetomidine-ketamine, are evaluated. Eighteen cats were anaesthetized twice each 5 min after premedication with atropine 0.04 mg/kg using midazolam 0.5 mg/kg, medetomidine 0.02 mg/kg and ketamine 2.0 mg/kg intramuscularly in one syringe. Because this study was conducted in co-operation with a dental prophylaxis project, cats had to be immobilized for approximately 1 h. Therefore, anaesthesia was prolonged with propofol to effect, if necessary. After 68+/-11 min on average, immobilization was partially reversed by either atipamezole 0.05 mg/kg subcutaneously (group A/SC, n=7) or intravenously (group A/IV, n=10), or by atipamezole 0.05 mg/kg and flumazenil 0.05 mg/kg subcutaneously (group AF/SC, n=10) or intravenously (group AF/IV, n=9), respectively. These four groups were additionally compared with a non-reversed group. Recovery time and total time of immobilization (until cats regained a standing position) were not significantly shortened using the antagonists. However, unconsciousness and sedation (expressed through parameters like the time taken to head lifting, crawling, sitting and the return of righting reflex) were significantly shortened by the antagonists, especially if administered intravenously. Abnormal behaviour, such as vocalization, licking, hyperaesthesia, restlessness or salivation, was observed in all groups. However, excitation and hyperaesthesia were not observed in group AF/IV, whereas in this group only intensified salivation occurred. The addition of flumazenil showed no significant difference to atipamezole alone, but subcutaneous administration of atipamezole alone was not sufficient in the dosage used to show an advantage compared to non-reversed cats.     

Partial Hepatic Resection for Treatment of a Single Liver Abscess in a Dairy Heifer

A single large hepatic abscess in a 10 month old Holstein heifer was treated successfully by partial hepatic resection. No complications or recurrence of clinical signs have developed in the 9 months since the resection. Partial hepatic resection is an effective treatment of solitary bovine liver abscesses that warrants further investigation.     

Long-Term Clinical Outcome After Partial Ligation of Single Extrahepatic Vascular Anomalies in 20 Dogs

This study reports the long-term clinical outcome after partial ligation of single extrahepatic vascular anomalies in 20 dogs. Outcome was classified as successful or complicated based on review of follow-up evaluations that consisted of telephone contacts with owners and veterinarians (n = 20), in hospital reevaluation (n = 15), and per-rectal portal nuclear scintigraphy (n = 12). Partial ligation was initially effective in resolving clinical signs in all 20 dogs. Long-term outcome was completely satisfactory in 50% of the cases. The mean time interval between surgery and onset of signs, or diagnosis of complications in the 10 dogs with a complicated outcome, was approximately 3 years. Central nervous system, gastrointestinal, and complications related to the urinary tract were most common. Acquired multiple extrahepatic venous communications occurred in at least 3 of 10 dogs (30%) with a complicated outcome. Long-term survival occurred in 13 of 20 dogs (65%) with partial ligation. The mean survival time for the seven dogs that died or were euthanatized was 3.6 years and the mean survival time for the 13 dogs still alive at the last follow-up was 5.0 years.     

陕西省部分地区猪圆环病毒2型全基因组的遗传变异分析

为了解陕西省猪圆环病毒2型(PCV2)的遗传变异情况,根据GenBank登录的PCV2全基因组序列,设计1对引物,从陕西省部分地区规模化猪场疑似PCV2感染的病猪采集病料9份,应用PCR扩增PCV2的全基因,其中6份为阳性,并对扩增的6个PCV2全基因组序列进行测序和序列分析。基因测序表明,PCV2基因组全长为1 767bp;对6株病毒序列进行同源性比较,6个毒株全基因之间核苷酸同源性为98.3%~100%,与GenBank上已发表的国内外毒株全基因组比较,同源性为96.3%~97.8%;与近几年陕西株比较发现基因变异程度不稳定,与2013年分离株(KX352154.1)同源性最高,2015年分离株(KX352159.1)次之,反而与2014年分离株(KX068219.1)最低;对6个毒株的ORF1和ORF2基因进行同源性比较,6个毒株的ORF1和ORF2基因的核苷酸同源性分别为98.1%~100%和98.2%~100%,与GenBank上已发表的国内外参考株ORF1和ORF2基因进行同源性比较,同源性分别为97.6%~99.8%和91.5~96.0%。陕西省流行的PCV2基因组较为保守,变异不大,同源性很高。     

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.