Congenital interruption of the portal vein and caudal vena cava in dogs: six case reports and a review of the literature

Imaging features of renal ectopia and fusion in 13 cats

CASE SERIES SUMMARY

A retrospective multicenter case series of renal fusion anomalies in cats was investigated. The aim of this study was to describe the imaging characteristics (radiography, ultrasonography and CT) of renal ectopia and fusion in cats. A total of 13 feline patients (median age 9 years) were included in this multicentric retrospective study. Ultrasound was available in 12/13 cases, radiographs in 4/13 cases and CT in 3/13 cases. Of the 13 cases, seven were left to right fusions, four were right to left fusions, one was on the midline and one was in the pelvic inlet. Adopting a human classification system, there were five lump kidneys, four disc kidneys, one horseshoe kidney, one caudal ectopia, one L-shaped kidney and one pelvic kidney. In 2/13 cases, additional congenital malformations were noted, including an azygous continuation of the caudal vena cava and a peritoneal-pericardial diaphragmatic hernia.

RELEVANCE AND NOVEL INFORMATION

This study provides further description of the imaging findings in feline patients with fused renal ectopia. The morphologic characteristics of the fused kidneys in cats appear similar to what is published in the human literature. Renal fusion might be an incidental finding in cats, but further investigations are necessary to determine their clinical relevance.

Reduced Klotho expression and its prognostic significance in canine hepatocellular carcinoma

Klotho is an anti-ageing gene and is known to act as a tumour suppressor in human hepatocellular carcinoma (HCC). According to a previous study, Klotho is present in normal canine mammary glands, and down-expression in tumours is positively associated with negative prognosis. However, the presence and significance of Klotho in canine HCC has not yet been reported. This study aimed to confirm Klotho expression in normal canine liver tissues using western blotting and immunohistochemistry, and whether the expression differed in non-neoplastic liver disease and HCC. Furthermore, correlation between clinicopathologic features and expression of Klotho was evaluated. All of the normal liver tissues showed the presence of Klotho, and Klotho expression was significantly decreased in the HCC tissue as compared to the non-neoplastic hepatic tissue. Additionally, Klotho expression was significantly associated with tumour size (P = .045), liver enzyme (alanine aminotransferase (ALT)) (P = .018), and metastasis (P = .024). Analysis of the survival curve revealed that reduced Klotho expression was significantly associated with poor disease-free survival (P = .041) in HCC. These results show that Klotho expression is present in normal canine liver tissue and that reduced Klotho expression is associated with poor prognosis in canine HCC. Thus, Klotho was presumed to be a potential clinical prognostic marker for canine HCC.

Computed tomographic appearance of transcaval ureter in two dogs and three cats: A novel CVC congenital malformation

Transcaval ureter is a rarely reported human congenital malformation of the prerenal segment of the inferior vena cava (IVC) not yet reported in veterinary medicine. The objective of this multicenter retrospective case series study was to describe the computed tomography (CT) features of transcaval ureters in dogs and cats. Patients referring to pre- and post-contrast CT exams of the abdomen and presenting this abnormality were retrospectively included. Multiple qualitative features were described for each ureteral abnormality detected. Three cats and two dogs with transcaval ureter were identified consisting of a segmental duplication of the CVC at the prerenal level creating a vascular ring through which the ureter extended, identified as a double-barrel gun sign. The malformation was divided into two types according to the symmetry of the caval branches and location in relation to the aorta, namely, type I symmetrical branches and right-lateral to the aorta, and type II asymmetrically branches and right-dorsal to the aorta. In one case, the malformation was associated with hydroureter and mild pyelectasis. In three cases, the anomaly was incidental and, in the remaining two cases, the clinical significance was uncertain. This is the first study describing the presence of transcaval ureter in dogs and cats. CT was a suitable method for the diagnosis of transcaval and a focal double-barrel gun sign of the CVC is proposed as the hallmark feature of this anomaly. The clinical relevance of this congenital vascular malformation is unclear and needs to be further investigated.

Case report: Application of three-dimensional technologies for surgical treatment of portosystemic shunt with segmental caudal vena cava aplasia in two dogs

This case report describes the application of three-dimensional (3D) technologies for the surgical treatment of portosystemic shunt (PSS) with segmental caudal vena cava (CVC) aplasia. Two client-owned dogs were diagnosed with PSS along with segmental CVC aplasia using computed tomography. Through 3D volume and surface rendering, the vascular anatomic anomaly of each patient was identified in detail. A patient-specific 3D vascular model was used for preoperative planning. According to the plan established based on the 3D rendered image and printed model, shunt occlusion was performed using cellophane banding in the first case. An ameroid constrictor was used in the second case. Both patients showed good recovery without any clinical symptoms or complications. The use of 3D technologies in small animals has many advantages, and its use in vascular surgery, as in these cases, is also a therapeutic option worth considering.

Dynamic Obstruction of an Anomalous Cavoazygos Vessel Associated with Interrupted Caudal Vena Cava in a Boxer Dog

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A young boxer dog presented for intermittent weakness associated with exercise.

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Dynamic physical exam findings and echocardiographic study were dependent on recumbency.

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A diagnosis of interrupted caudal vena cava was made by computed tomography.

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Positional obstruction of anomalous cavoazygos vessel by the diaphragm was noted.

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Obstruction of anomalous vessel was associated with clinical signs.

Computed tomography diagnosis of a caval-azygos communication in a dog with cor triatriatum dexter

An 18-month-old Springer Spaniel was presented for investigation of ascites, exercise intolerance and suspected cor triatriatum dexter. Division of the right atrium into two separate chambers by an anomalous perforated membrane consistent with cor triatriatum dexter was confirmed during echocardiography. However, a routine agitated saline contrast (bubble) study yielded results that could not be explained by the congenital heart defect alone. Computed tomography angiography was performed and revealed a dilated ventral internal vertebral venous plexus and a short, dilated vessel in the midlumbar region redirecting blood flow away from the caudal vena cava and into the azygos vein. Balloon dilatation of the orifice within the cor triatriatum dexter membrane successfully reduced pressure within the caudal chamber of the right atrium and enhanced return via the caudal vena cava with subsequent resolution of clinical signs. This case report highlights the use of cross-sectional imaging in dogs with cor triatriatum dexter and unexpected contrast study results, as a means by which concurrent vascular anomalies may be identified.

Surgical treatment of an abnormally positioned right adrenal tumor on segmental caudal vena cava aplasia in two dogs

Segmental caudal vena cava (CVC) aplasia is a rare congenital vascular anomaly in dogs. Two dogs were diagnosed by CT imaging to have right adrenal tumors with concomitant segmental CVC aplasia. During surgery, a firm connection between the right adrenal gland and CVC was observed in both cases. The adrenal glands were found ventral to the CVC and the adrenal tumor was resected including the vascular wall. CVC venectomy for tumor removal will be required if the right adrenal gland is displaced in dogs with segmental CVC aplasia, even if there is no intravascular invasion.

CT variants of the caudal vena cava in 121 small breed dogs

Computed tomography is increasingly used as a treatment planning method in canine patients with diseases of the retroperitoneum, however, published information on normal variations in the caudal vena cava (CVC) are currently lacking. The objectives of this retrospective descriptive study were to characterize CVC variants using CT angiography in a sample of small breed dogs and localize the CVC bifurcations for each variant. Inclusion criteria were small breed dogs (weight ≤ 15) that underwent contrast-enhanced CT scans of the CVC, abdominal aorta, and CVC tributaries. A total of 121 small breed dogs were sampled. Four right-sided and one left-sided CVC variations were identified: normal (88/121, 72.7%), caudal-partial split (17/121, 14.0%), partial duplication (8/121, 6.6%), complete duplication (7/121, 5.8%), and left-sidedness (1/121, 0.8%). The mean lumbar vertebral levels of the CVC bifurcation were L6.39 ± 0.41, L5.70 ± 0.35, L4.39 ± 0.42, L2.74 ± 0.38, and L6.4 in the normal, caudal-partial split, partial duplication, complete duplication, and left-sidedness types, respectively. The location of the CVC bifurcation, the relationship between the aortic trifurcation and the CVC bifurcation, and the location of the bilateral deep circumflex iliac veins with respect to the CVC bifurcation were significantly different among the right-sided types (P ≤ .001). Bilateral deep circumflex iliac veins joined to the ipsilateral common iliac veins and the CVC in the caudal-partial split and duplication types, respectively. The results of this study indicated that canine CVC variants may be frequent and should be considered during surgery or diagnostic imaging of the retroperitoneum.

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

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

Multimodality imaging of an azygous continuation of the caudal vena cava in a dog with pulmonary thromboembolic disease

A 5-year-old spayed female English Bulldog was evaluated for acute anorexia, lethargy, respiratory distress, and syncope. Contrast-enhanced computed tomography revealed the vascular malformation of azygous continuation of the caudal vena cava with extensive thrombus formation and pulmonary arterial thromboembolic disease. The patient was hospitalized for supportive treatment and was prescribed long-term clopidogrel therapy. The patient survived to discharge and at last follow-up remained clinically stable. While this vascular malformation has been reported in canines, to the authors' knowledge, this is the first reported case of pulmonary thromboembolic disease in a canine concurrent with this condition.

Azygos continuation of the caudal vena cava with segmental aneurysm, lung lobe torsion and pulmonary thromboembolism in a dog

This case highlights the management and diagnostic evaluation of a dog with two individually rare conditions (lung lobe torsion and vena cava aneurysm) that ultimately resulted in fatal pulmonary thromboembolism.

Congenital absence of the portal vein in a cat

CASE SUMMARY

A 9-month-old female neutered domestic shorthair cat presented with a history of episodic ptyalism, lethargy and abnormal behaviour. The clinical signs together with elevated pre- and post-prandial bile acid concentrations were consistent with hepatic encephalopathy (HE). In the absence of a portosystemic shunt (PSS) on abdominal ultrasound, medical management of HE was established with a protein-restricted diet and lactulose and the neurological signs resolved. Following an episode of acute vomiting and haemorrhagic diarrhoea at 19 months of age abdominal ultrasonography was repeated. The portal vein could not be demonstrated ultrasonographically; instead, portal vein tributaries were tortuous and communicated with the caudal vena cava (CdVC) at the level of the left kidney. CT angiography (CTA) confirmed the absence of the portal vein. CTA demonstrated the tortuous terminations of the portal tributaries, and several systemic veins, draining into the CdVC via a large-diameter paracaval vessel at the level of the left kidney. Gastrointestinal signs were stabilised and medical management for HE of a protein-restricted diet and lactulose was re-established.

RELEVANCE AND NOVEL INFORMATION

Congenital absence of the portal vein has not been described previously in the cat and should be considered in cats presenting with signs suggestive of a PSS and HE. The portal vein in the cat can be demonstrated using ultrasound, but complex congenital vascular malformations of the portal or systemic abdominal veins should be characterised using CTA and further distinguished from other vascular anomalies that may present with similar ultrasonographic features.

Computed tomography angiography of situs inversus, portosystemic shunt and multiple vena cava anomalies in a dog

A 5-year-old Shih Tzu was presented with intermittent vomiting and anorexia. Microhepatica and reversed position of the abdominal organs were observed on radiography. Ultrasonographically, portosystemic shunt (PSS) was tentatively diagnosed. Computed tomography (CT) revealed that the distended portal vein drained into the left hepatic vein. The caudal vena cava (CdVC) split postrenally and converged at the renal level. Cranial to this, the azygos continuation of the CdVC was confirmed. In the thorax, a persistent left cranial vena cava (CrVC) was found along with right CrVC. This is the first report of a dog with persistent left CrVC and multiple abdominal malformations. CT angiography was useful in evaluating the characteristics of each vascular anomaly and determining the required surgical correction in this complex case.

Shunting Between the CVC and Both the Azygos Vein and Thoracic Duct in a Dog with CTDS

A 5 mo old female rottweiler was referred for evaluation of a suspected congenital heart disease. Clinical signs included anorexia, exercise intolerance, and severe loss of body condition. Clinical examination revealed dyspnea, pale mucous membranes, and weak femoral pulses. Pleural and abdominal effusions and iron deficiency anemia were identified. A distended intrathoracic caudal vena cava (CVC) visible on thoracic radiographs suggested that the modified transudate abdominal effusion was the result of improper venous return to the right side of the heart. Cor triatriatum dexter (CTD) was diagnosed via echocardiography but did not explain all the anomalies detected during a contrast echocardiography. Abnormal communications between the CVC and azygos vein and the CVC and thoracic duct were subsequently identified by abdominal ultrasonography and angiography. Medical management with diuretics, iron supplements, and surgical treatment of CTD resulted in normalization of the respiratory rate, the exercise intolerance, and the anemia. To the authors’ knowledge, this is the first reported case of CTD associated with shunts between the CTV and both the azygos vein and thoracic duct in dogs. This report emphasizes the importance of presurgical assessment of concurrent thoracic and abdominal congenital vascular abnormalities.

Computed tomography findings in portal vein aneurysm of dogs

In this retrospective study, the appearances of extrahepatic and intrahepatic portal vein aneurysms (PVAs) in dogs were evaluated using multidetector computed tomography (CT). Data from 3060 dogs that underwent abdominal CT were reviewed for focal portal vein dilatation. PVAs were detected in 15/3060 (0.49%) dogs. The bodyweights of dogs with PVAs were significantly higher than the bodyweights of dogs without aneurysms (P=0.0001). Male sex was also significantly associated with PVAs (OR=6.23). Boxers were predisposed to the development of PVA (OR=11.88). Extrahepatic PVAs were always located in the portal vein at the level of the gastroduodenal vein insertion and were saccular in 10/15 dogs and fusiform in 5/15 dogs. One dog had an additional intrahepatic aneurysm of the umbilical part of the left intrahepatic portal branch. No dogs had clinical signs related to the PVA(s), although one dog developed a portal vein thrombosis in the site of the aneurysm.

Prenatal Development of the Caudal Vena Cava in Mammals: Review of the Different Theories with Special Reference to the Dog

Several items of the development of the caudal vena cava in domestic animals are still controversial. In particular, the origin of the lumbar segment of the caudal vena cava is equivocally described. According to different theories it originates from the right-sided supracardinal, caudal cardinal, sacrocardinal, lateral sympathetic or subcardinal veins. In this review, all five theories are compared with each other and discussed in the light of anatomical variations observed in eight dogs. Species-specific diversity, erratic observations because of technical artefacts, and biased interpretation of the original data are three major reasons for the dissimilarity between the five theories, but they cannot explain all differences. Further studies by using modern techniques such as microvascular corrosion casting and non-invasive three-dimensional microtomography are necessary to better understand the normal development and to explain the variations in domestic animal species.

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.

Massive hepatocellular carcinoma in dogs: 48 cases (1992-2002)

OBJECTIVE

To determine clinical signs, diagnostic findings, outcome, and prognostic factors in dogs treated surgically for massive hepatocellular carcinoma (HCC) and compare survival times of surgically and conservatively treated dogs.

DESIGN

Retrospective study.

ANIMALS

48 dogs.

PROCEDURE

Medical records were examined for clinical signs, diagnostic and surgical findings, and postoperative outcome. Dogs were allocated into surgery and nonsurgery groups depending on whether curative-intent liver lobectomy was performed. Data from the surgical and nonsurgical groups were analyzed to identify prognostic factors and determine and compare rates of tumor control and survival time.

RESULTS

42 dogs were treated surgically, and 6 were managed conservatively. In the surgery group, intraoperative mortality rate was 4.8% with no local recurrence, metastatic rate was 4.8%, and median survival time was > 1,460 days (range, 1 to 1,460 days). High alanine aminotransferase and aspartate aminotransferase activities were associated with poor prognosis. Median survival time for the nonsurgery group was 270 days (range, 0 to 415 days), which was significantly less than that of surgically treated dogs.

CONCLUSIONS AND CLINICAL RELEVANCE

Liver lobectomy is recommended for dogs with massive HCC because tumor-related mortality rate was 15.4 times higher in dogs in the nonsurgery group, compared with the surgery group. Tumor control was excellent after surgical resection with no local recurrence and a low metastatic rate. Prognostic factors were identified, but their clinical relevance was uncertain because only 9.5% of dogs in the surgery group died as a result of their disease.

Congenital extrahepatic portosystemic shunts

BACKGROUND

A congenital extrahepatic portosystemic shunt (CEPS) is uncommon. A type 1 CEPS exists where there is absence of intrahepatic portal venous supply and a type 2 CEPS where this supply is preserved. The diagnosis of congenital portosystemic shunt is important because it may cause hepatic encephalopathy.

OBJECTIVE

To describe the clinical and imaging features of three children with CEPS and to review the cases in the published literature.

MATERIALS AND METHODS

The diagnostic imaging and medical records for three children with CEPS were retrieved and evaluated. An extensive literature search was performed.

RESULTS

Including our cases, there are 61 reported cases of CEPS, 39 type 1 and 22 type 2. Type 1 occurs predominantly in females, while type 2 shows no significant sexual preponderance. The age at diagnosis ranges from 31 weeks of intrauterine life to 76 years. Both types of CEPS have a number of associations, the most common being nodular lesions of the liver ( n=25), cardiac anomalies ( n=19), portosystemic encephalopathy ( n=10), polysplenia ( n=9), biliary atresia ( n=7), skeletal anomalies ( n=5), and renal tract anomalies ( n=4).

CONCLUSION

MRI is recommended as an important means of diagnosing and classifying cases of CEPS and examining the associated cardiovascular and hepatic abnormalities. Screening for CEPS in patients born with polysplenia is suggested.

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

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

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.