Caudal vena cava kinking in dogs with ascites

A 9-year-old dog with spontaneous ascites was found to have hepatic vein distension and a tortuous vena cava on abdominal ultrasound. In right lateral recumbency, the caudal vena cava crossed the diaphragm and became kinked before entering into the right atrium. Following this observation, we performed an experimental study in a normal dog to determine whether kinking of the caudal vena cava could be the result and not the cause of ascites. Ascites was induced using warm saline injected through a needle inserted into the abdominal cavity. Venograms were collected from different body positions, under four conditions: before and after a total of one, two and 3 liters of saline had been injected. Caudal vena cava kinking was observed in the experimental dog after 2 liters of fluid had been injected. Vena cava obstruction may cause ascites, but we found that sometimes caudal vena cava kinking can be the result and not the cause of the peritoneal effusion.     

Passive liver congestion associated with caudal vena caval compression due to oesophageal leiomyoma

A large caudodorsal mediastinal mass was identified in a dog which had been presented for vomiting and anorexia. A few weeks later, the dog developed ascites and hindlimb oedema. Radiography showed that the caudodorsal mediastinal mass was compressing the caudal vena cava, probably inducing passive congestion of the liver. At postmortem examination, the mass was diagnosed as a large oesophageal leiomyoma. To the authors' knowledge, an oesophageal tumour leading to compression of the caudal vena cava associated with passive congestion of the liver has not been described previously in dogs. Secondary signs relating to the oesophageal mass appeared to be more prominent than the digestive signs. Causes of passive congestion of the liver and the differential diagnoses for a caudodorsal mediastinal mass are discussed.     

Thrombosis of the caudal vena cava presenting as an unusual cause of an abdominal mass and thrombocytopenia in a dog

Thrombosis of the caudal vena cava in a dog secondary to metastatic neoplasia is described. The dog had a palpable abdominal mass and persistent thrombocytopenia due to a thrombosed caudal vena cava that was surgically removed. A few days after its removal, the dog died and neoplastic cells of neural crest origin were identified at the edge of the thrombus. Massive thrombosis can be an unusual cause of platelet consumption, leading to thrombocytopenia and disseminated intravascular coagulation. Deep vein thrombosis of the vena cava can occur in dogs and may mimic an abdominal mass. Multiple mechanisms may be involved in the development of venous thrombosis, including endothelial damage by neoplastic cells and the presence of a hypercoagulable state secondary to neoplasia. Extensive collateral circulation may allow removal of diseased vena cava.     

Phaeochromocytoma treated by en bloc resection including the suprarenal caudal vena cava in a dog

A 10-year-old, neutered male Cairn terrier was examined after experiencing intermittent vomiting of several months' duration and sudden onset of acute depression. Abdominal ultrasound examination revealed an adrenal mass invading the suprarenal part of the caudal vena cava. The vascular invasion could not be corrected so en bloc ligation/excision of the adrenal neoplasm and the suprarenal part of the vena cava was performed. Microscopic examination identified an adrenal phaeochromocytoma. The dog recovered well and had no significant vascular or renal dysfunction at follow-up 20 months after surgery. To the authors' knowledge, this is the first report of a dog surviving long term after resection of the suprarenal caudal vena cava.     

Chronic peritoneal effusion secondary to partial caudal vena cava obstruction following traumatic pneumothorax in a dog.

A three-year old, female Boxer Dog was treated initially with thoracocentesis for a right-sided pneumothorax. The dog was re-evaluated after three weeks because of an enlargement of the abdomen. A positive venogram revealed a ventral displacement of the caudal vena cava between the diaphragm and the heart, with a severe reduction of the diameter of the vein. An exploratory thoracotomy showed a displaced accessory lung lobe with an adhesion to the parietal pleura. Inflation of this lung lobe created a dynamic obstruction of the caudal vena cava, which resulted in ascites. Surgery offered successful treatment.     

Budd–Chiari-like syndrome in a dog with a chondrosarcoma of the thoracic wall

Objective: To describe a dog with Budd–Chiari‐like syndrome secondary to caudal vena cava compression from a thoracic wall chondrosarcoma. Case summary: A 9‐year‐old spayed female Shetland Sheepdog cross with a recent history of non‐productive cough developed severe abdominal distension and dyspnea. Marked ascites and enlarged hepatic veins were identified with ultrasonography. At surgery, a right thoracic wall mass was found to be compressing the caudal vena cava. Fluid analysis of the ascites revealed a modified transudate with elevated protein concentration, consistent with Budd–Chiari‐like syndrome. Clinical signs resolved following thoracotomy and complete resection of the mass. New or unique information provided: Obstruction of venous blood flow can result from compression exerted by a space‐occupying thoracic wall mass on the caudal vena cava. Clinical resolution can be achieved with return of adequate venous circulation by removal of the mass and alleviation of the external pressure.     

Surgical treatment of right-sided renal lymphoma with invasion of the caudal vena cava

An eight-year-old, male castrated basset hound presenting with a three-month history of lethargy was examined. Diagnostic tests including radiography and ultrasonography showed a right-sided renal mass. A 99mTc diethylenetriamine penta-acetic acid scan demonstrated that this kidney was non-functional. At surgery, invasion of the caudal vena cava was found, and the renal segment of the vena cava and the right kidney were resected. The left renal vein was anastomosed to the more proximal vena cava using a polytetrafluoroethylene graft, and the dog recovered well. Two days postsurgery, the dog suffered an acute episode of aspiration pneumonia and was euthanased. The renal mass was diagnosed as lymphoma on histopathology.     

49-month survival following caval venectomy without nephrectomy in a dog with a pheochromocytoma

An 11 yr old spayed female Labrador retriever was diagnosed with a right adrenal tumor. At surgery, adhesions to the right kidney were dissected, allowing the right kidney to be preserved. The tumor showed extensive invasion into the suprarenal vena cava. It was felt that thrombus removal via venotomy could not be performed. Instead, the vena cava was ligated caudal to the liver and cranial to the right renal vein. The neoplastic gland was then excised en bloc together with the portion of the invaded caudal vena cava. Hind limb edema had developed preoperatively and increased transiently in the first days postoperatively. The animal was discharged 6 days postoperatively with no other clinical disorders, and hind limb edema resolved over time. Histopathology identified a pheochromocytoma. The dog died 49 mo later. A neoplastic thrombus of the vena cava may require venotomy to allow thrombus removal. Occasionally, removal of the thrombus by venotomy may prove impossible. In such a situation, en bloc removal of the concerned portion of the vena cava may be performed with a good long-term outcome provided that gradual occlusion of the vena cava by the thrombus has allowed time for collateral circulation to develop.     

Combined chylothorax, chylopericardium, and cranial vena cava syndrome in a dog with thymoma

A dog was examined because of anorexia and development of submandibular, sternal, and forelimb edema. Physical examination revealed engorged jugular veins and engorged blood vessels of the conjunctivae and nictitating membranes. Thoracic radiography revealed pleural and pericardial effusions, later identified as chyle. Contrast angiography revealed an intravascular mass, later identified as thymoma, in the cranial vena cava.     

Transvenous retrograde portography for identification and characterization of portosystemic shunts in dogs

Transvenous retrograde portography for identification and characterization of portosystemic shunts in dogs A method for transvenous retrograde portography (TRP) in dogs suspected to have a portosystemic shunt (PSS) and results in 20 dogs are described. For TRP, dogs were anesthetized and positioned in left lateral recumbency A dual-lumen balloon-tipped catheter was inserted into the right jugular vein and advanced into the azygos vein. The balloon was inflated to occlude the azygos vein, and contrast material was injected during fluoroscopic evaluation. The catheter was then positioned in the caudal vena cava just cranial to the diaphragm. The balloon was again inflated to occlude the vena cava, and contrast material was again injected. Once a shunt was identified, selective catheterization was attempted with a guide wire and angled catheter. A PSS was identified in 18 of the 20 dogs. In 10 of the 18, the shunt vessel could be selectively catheterized, allowing measurement of portal pressures while the shunt was occluded with the balloon. In 1 dog, results of TRP were normal, but subsequent exploratory celiotomy revealed a single extrahepatic PSS, which was surgically attenuated. The other dog in which results of TRP were normal did not have a macroscopic PSS. In dogs suspected to have a PSS, TRP may be a useful adjunctive diagnostic test that is less invasive than operative mesenteric vein portography and allows measurement of portal pressures before and after temporary shunt occlusion.     

Caudal vena cava thrombosis-like syndrome in a horse

A 9-year-old Quarter horse was presented for chronic refractory pneumonia. On necropsy, an hepatic abscess, caudal vena cava thrombosis, pulmonary thromboembolism, and embolic pneumonia were identified. Similar lesions have been reported in cattle as caudal vena cava thrombosis syndrome, however this syndrome has not previously been reported in horses.     

Congenital obstruction of the caudal vena cava in a dog

A 16-week-old female Rottweiler was examined because of labored breathing and abdominal distention. Ascites, hepatomegaly, and pleural effusion were detected during physical and radiographic examinations. Selective angiography revealed a stenotic lesion at the junction of the caudal vena cava and the right atrium. A fibrous diaphragm with a pin-hole orifice was observed at surgery. Clinical signs of disease resolved after successful removal of the membranous obstruction.     

MULTIDETECTOR‐ROW COMPUTED TOMOGRAPHIC CHARACTERISTICS OF PRESUMED PREURETERAL VENA CAVA IN CATS

Preureteral vena cava (circumcaval ureter, retrocaval ureter) occurs in a third of the feline population and has been associated with ureteral strictures in humans. The aim of this retrospective cross‐sectional study was to describe the contrast‐enhanced multidetector row computed tomographic (MDCT) characteristics of presumed preureteral vena cava in a group of cats. Medical records from two institutions located in different continents were searched from 2010–2013 for cases with complete contrast‐enhanced MDCT examinations of the abdomen (i.e. included the entire course of the ureters and prerenal and renal segments of the caudal vena cava) and a diagnosis of preureteral caudal vena cava. For cases meeting inclusion criteria, CT scan data were retrieved and characteristics of the preureteral caudal vena cava were recorded. Presence of concomitant renal or ureteral diseases was also recorded. A total of 272 cats had contrast‐enhanced abdominal CT scans during the study period and of these, 68 cats (22.43 ± 4.96%) had a diagnosis of presumed preureteral vena cava. In all affected cats, a “reverse‐J ureter” was observed, i.e. a ureter running medially at the level of L4–5, passing dorsally to the caudal vena cava and then exiting ventrally between the caudal vena cava and aorta returning to its normal position. Having a preureteral vena cava resulted in an increased risk for concurrent urinary signs (OR = 3.00; CI: 95%; 1.28–6.99; P = 0.01). Findings supported the use of contrast‐enhanced MDCT for characterizing morphology of preureteral vena cava and its relation with ureters in cats.     

Ultrasonographic measurement of caudal vena cava to aorta ratios for determination of volume depletion in normal beagle dogs

A noninvasive method for quantifying hydration status would be helpful for clinical management and for research applications in dogs. This prospective, experimental, pilot study aimed to assess the feasibility of ultrasonographic measurement of the caudal vena cava to aorta ratio as a method for quantifying volume depletion in dogs. In 12 normal beagle dogs, furosemide was administered intravenously at a dose of 1 mg/kg, every 2 h, for 8 h, to induce consecutive volume depletion. Every 30 min after administration, ultrasonographic images of the caudal vena cava and aorta, and physical and biological parameters related to dehydration were acquired. On transverse and longitudinal planes of caudal vena cava and aorta images, the height and area of the caudal vena cava and aorta were measured to calculate the caudal vena cava/aorta ratios. All images were acquired by approaching from the right intercostal space with the dogs in left lateral recumbency. A negative correlation was present between the percentage of weight loss in dogs and all four investigated caudal vena cava/aorta ratios (transverse plane width of the caudal vena cava [TW]/aorta; transverse plane height of caudal vena cava [TH]/aorta; longitudinal plane area of the caudal vena cava [TA]/aorta; and longitudinal plane maximal height of the caudal vena cava [L]/aorta). Significant differences (P < 0.001) were seen between dogs with and without clinical signs of dehydration for all caudal vena cava/aorta ratios. Findings indicated that ultrasonographic caudal vena cava/aorta ratios are feasible methods for quantifying volume depletion and for use as an adjunct to standard subjective methods for estimating hydration status in dogs.     

ULTRASONOGRAPHIC DIAGNOSIS: CRANIAL VENA CAVA THROMBOSIS IN A COW

A 5-year-old Hereford cow was donated to Oregon State University, College of Veterinary Medicine. Two weeks before presentation the cow was treated by a left-flank laparotomy to correct a uterine torsion that revealed an excessive amount of abdominal fluid and a full term dead fetus. Ultrasonographic evaluation of the right cranioventral thoracic cavity was performed owing to physical examination (muffled heart sounds, areas of silence) and thoracocentesis findings suggestive of pleuritis. Ultrasonography revealed hypoechoic pleural effusion and a mass of mixed echogenicity visible within the right atrial lumen extending into the cranial vena cava. A diagnosis of cranial vena cava thrombosis was demonstrated at necropsy. The clinical, ultrasonographic, and pathological features of this less common condition (cranial vena cava thrombosis) in cattle are discussed.     

Diagnosis by ultrasonography of congestion of the caudal vena cava secondary to thrombosis in 12 cows

This paper describes the clinical, ultrasonographic, radiographic and postmortem findings in 12 cows with thrombosis of the caudal vena cava. The principal clinical signs were chronic bronchopneumonia and fever in 11 cows; one cow had epistaxis and one cow bled from the mouth; eight cows had anaemia and leucocytosis, and the clotting time for the glutaraldehyde test was markedly decreased in all the cows; in nine of the cows the activity of gamma-glutamyltransferase was high, suggesting chronic hepatic congestion. The most important ultrasonographic finding was congestion of the caudal vena cava attributable to thrombosis of the vein. In all the cows the caudal vena cava was round to oval on cross-section, rather than the normal triangular shape. The hepatic, splenic and portal veins were dilated in five, three and one cow, respectively. The results of radiography and endoscopy supported a diagnosis of bronchopneumonia, but there were radiographic changes in the diaphragmatic lung lobes that supported a diagnosis of vena caval disease in only four cows. Postmortem there was a thrombosis of the caudal vena cava in all the cows, and the thrombi were located in the thoracic, subphrenic and abdominal part of the caudal vena cava at the level of the liver in four, one and seven cows, respectively. In three cows, the thrombus was situated where a hepatic abscess had broken into the caudal vena cava, and in one cow it was at the site of a diaphragmatic abscess. In another cow, there was a fistula between the major bronchus of the right diaphragmatic lung lobe and the caudal vena cava where the thrombus was situated. Three cows had liver abscesses that had not broken into the caudal vena cava. There was severe bronchopneumonia in 11 of the cows, some of which also had multiple pulmonary abscesses.     

Extensive venous thrombosis and hind-limb edema associated with adrenocortical carcinoma in a dog.

A 10-year-old, spayed female, mixed-breed dog was referred for evaluation of bilateral hindlimb edema and weakness. Abdominal ultrasonography showed increased echogenicity of the lumen of the caudal vena cava from the level of the urinary bladder to the level of the cranial pole of the right kidney. Bilateral saphenous venograms displayed numerous filling defects in the caudal vena cava, right external iliac vein, right femoral vein, and the right common iliac vein. Extensive venous thrombosis was diagnosed, and the animal was euthanized. Necropsy confirmed the presence of venous thrombosis and revealed a right adrenocortical carcinoma that had invaded the caudal vena cava.     

IMAGING DIAGNOSIS—PORTAL VEIN APLASIA AND INTERRUPTION OF THE CAUDAL VENA CAVA IN THREE DOGS

Severe portal vascular anomalies have been reported previously accompanying azygos continuation of the caudal vena cava, polysplenia, and situs anomalies in dogs and people. Three dogs with portal vascular anomalies were identified by means of CT angiography as having portal vein aplasia with portal insertion into the caudal vena cava, azygos continuation of the caudal vena cava, and interruption of the pre‐hepatic caudal vena cava. This information confirms that complex embryological defects may occur in patients presenting for congenital portosystemic shunt, and that CT angiography is a non‐invasive method of completely evaluating these potentially non‐surgical portal vascular anomalies.     

Computed tomographic and magnetic resonance imaging features of canine segmental caudal vena cava aplasia

O bjective : To describe the computed tomographic and magnetic resonance imaging features of segmental caudal vena cava aplasia and associated vascular anomalies in dogs.
M ethods : A retrospective study was performed reviewing computed tomographic and magnetic resonance imaging archives of eight institutions for dogs with segmental caudal vena cava aplasia. Inclusion criteria included a computed tomographic or magnetic resonance imaging study and supportive diagnostic and follow-up information. Abdominal vessels were reviewed for size, shape, location and course (including tributaries and branches) and classified as normal, abnormal or shunt vessels.
R esults : Ten dogs with segmental caudal vena cava aplasia were identified. In all dogs, postrenal caval blood was shunted to either a right or a left azygos vein, with seven different angiographic patterns. Affected dogs were predominantly female (70 per cent) and young (mean 2·6 years). Additional portocaval and porto-azygos shunt vessels were identified in two cases each. Computed tomographic angiography and magnetic resonance angiography depicted details of abdominal vessels including thrombus formation in one dog.
C linical S ignificance : Segmental caudal vena cava aplasia is a vascular congenital anomaly in the dog that can be associated with thrombosis and portosystemic shunts. Computed tomographic angiography and magnetic resonance angiography are excellent tools to demonstrate the complex vascular anatomy and to guide treatment planning for portosystemic shunts and thrombolytic therapy.     

MYELOPATHY SECONDARY TO AORTOCAVAL FISTULA IN A CAT

A 15-month-old neutered male cat was presented for progressive paraparesis of 3 months' duration and suspected cardiomegaly. Neuroanatomical localization was a T3-L3 myelopathy. On abdominal ultrasound, an anomalous vessel with turbulent blood flow was identified arising from the caudal vena cava. Myelography showed a bilateral ventrolateral extradural spinal cord compression from T12 to L4. Nonselective angiography and contrast-enhanced computed tomography clearly indicated a vascular complex and vena caval aneurysm with an engorged internal vertebral venous plexus. Surgical occlusion of the anomalous vessels was unsuccessful.