Use of recombinant tissue-plasminogen activator in a dog with chylothorax secondary to catheter-associated thrombosis of the cranial vena cava

A 4-year-old, castrated male Maltese developed cranial vena caval thrombosis and chylothorax following central venous catheterization for treatment of postoperative sepsis. Vena caval thrombolysis was attempted using recombinant human tissue-plasminogen activator (t-PA). Thrombolytic therapy led to an acute reduction in the size of the caval thrombus and was followed by prompt resolution of the chylothorax. Hemorrhage at the entry sites of a jugular catheter and esophagostomy tube placed at the time of treatment was a dose-limiting complication of t-PA therapy in this dog.     

Macroscopic Anatomy of the Great Vessels and Structures Associated with the Heart of the Ringed Seal (Pusa hispida)

The ringed seal [Pusa (Phoca) hispida], as well as other seals, exhibits unique anatomical properties when compared to its terrestrial counterparts. In the ringed seal, the most conspicuous marine adaptation is the aortic bulb. This large dilatation of the ascending aorta is comparable to that found in other seal species and marine mammals. The branches of the ascending aorta (brachiocephalic trunk, left common carotid artery and left subclavian artery) are similar to those of higher primates and man. The peculiarities of the venous system are: three pulmonary veins, a pericardial venous plexus, a caval sphincter, a hepatic sinus with paired caudal vena cavae and a large extradural venous plexus. Generally, three common pulmonary veins (right, left and caudal) empty into the left atrium. The pericardial venous plexus lies deep to the mediastinal pericardial pleura (pleura pericardica) on the auricular (ventral) surface of the heart. The caval sphincter surrounds the caudal vena cava as it passes through the diaphragm. Caudal to the diaphragm, the vena cava is dilated (the hepatic sinus), and near the cranial extremity of the kidneys, it becomes biphid. The azygos vein is formed from the union of the right and left azygos veins at the level of the 5th thoracic vertebra. Cardiovascular physiological studies show some of these anatomical variations, especially of the venous system and the ascending aorta, to be modifications for diving. This investigation documents the large blood vessels associated with the heart and related structures in the ringed seal.     

Cranial vena caval syndrome secondary to transvenous pacemaker implantation in two dogs

Superior vena caval syndrome is a rare, but reported complication of transvenous pacemaker implantation in humans. This syndrome can occur secondary to fibrotic and/or thrombotic obstruction of venous blood flow into the right atrium. The therapeutic approach depends on the suspicion of the presence of an active thrombus and may include antithrombotics, angioplasty and/or surgical venoplasty. We describe two dogs that developed severe pleural effusion secondary to stricture formation in the cranial vena cava 4 years after dual chamber transvenous pacemaker implantation. The stenosis was most likely due to fibrosis secondary to the transvenous pacemaker leads. Balloon angioplasty of the lesion resulted in resolution of the pleural effusion in both patients. Balloon angioplasty appears to be a viable therapeutic approach in dogs with cranial vena caval syndrome caused by focal stenotic lesions.     

Blastomycosis granuloma involving the cranial vena cava associated with chylothorax and cranial vena caval syndrome in a dog

A four-year-old, sexually intact, male dachshund was diagnosed with pulmonary blastomycosis. Itraconazole was administered for 60 days, and the dog was considered to be disease-free at three- and 12-month reevaluations. Two years following discontinuation of itraconazole, the dog developed a granuloma of the cranial vena cava resulting in chylothorax and cranial vena caval obstruction. To the authors' knowledge, this is the first case of a blastomycotic granuloma involving the vena cava reported in the dog. Blastomycosis should be considered as a differential diagnosis for both chylothorax and cranial vena caval syndrome in the dog.     

Chylothorax associated with thrombosis of the cranial vena cava

This study reviewed confirmed cases of concurrent chylothorax and cranial vena caval (CrVC) thrombosis in dogs and cats, and determined predisposing factors for the development of chylothorax associated with CrVC thrombosis. The extent and location of the thrombus, the treatment regime, and the outcome are described. In all 4 cases, implantation of a jugular device was a predisposing factor to thrombosis of the CrVC, and there was extensive thrombosis of the CrVC extending from at least 1 jugular vein to just cranial to the heart. Chylothorax resolved in 3 of the 4 cases after medical and/or surgical intervention. The development of chylothorax concurrently with thrombosis of the CrVC in dogs and cats is likely dependent on the extent and location of the thrombus. Veterinary patients with indwelling jugular devices that develop acute respiratory signs should be assessed for chylothorax associated with thrombosis of the CrVC.     

Caudal vena caval thrombosis in a cow

Caudal vena caval thrombosis was diagnosed in a 13-year-old Santa Gertrudis cow with a history of chronic weight loss. Anemia, abnormal lung sounds, hemoptysis, and melena were the predominant clinical signs of vena caval thrombosis.     

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.     

Cranial vena cava aneurysm in a dog

A 1.5-year-old mixed breed dog was presented for evaluation of arrhythmia and a cranial mediastinal density was noted on thoracic radiographs. The density was determined to be a cranial vena cava aneurysm based on ultrasonographic and angiographic testing. No treatment was initiated and the dog remains asymptomatic for the cranial vena cava aneurysm at 6 years of age. Although rare, cranial vena cava aneurysm should be a differential diagnosis for dogs with cranial mediastinal abnormalities on thoracic radiographs.     

Biometrical Studies on the Cornea in Some Domestic Animals

The ringed seal ( Phoca hispida ), as well as other seals, exhibit some unique anatomical properties when compared to their terrestrial counterparts. In the ringed seal, the most conspicuous adaptation is the aortic bulb, a large dilatation of the ascending aorta, which is comparable to that found in other seal species and marine mammals. Coronary arteries are similar to those of terrestrial mammals. The branches of the ascending aorta (brachiocephalic trunk, left common carotid artery and left subclavian artery) are similar to those of higher primates and man. The pulmonary trunk originates from the right ventricle near the ventral midline of the thorax. The peculiarities of the venous system are three pulmonary veins, a pericardial venous plexus, a caval sphincter, a hepatic sinus with paired caudal vena cavae and a large extradural venous system. Generally, three pulmonary veins (right, left, middle) empty into the left atrium. The right and left pulmonary veins drain the cranial and middle lung lobes of their respective lung, while the middle pulmonary vein drains both caudal lung lobes and the accessory lobe. The pericardial venous plexus lies on the pericardial pleura on the auricular (ventral) surface the heart. The azygous vein is formed from the union of right and left azygous veins near the 5th thoracic vertebra. The caval sphincter surrounds the caudal vena cava as it passes through the diaphragm. Caudal to the diaphragm, the vena cava is dilated excessively (the hepatic sinus) and near the kidneys it is biphid. Cardiovascular physiological studies have shown some of these anatomical variations, especially of the venous system and the ascending aorta, to be modifications for diving.     

Ultrasound-guided biopsy as a diagnostic aid in three horses with a cranial mediastinal lymphosarcoma

An ultrasound examination of the thorax of three horses which were performing poorly or had mild signs of colic showed that they had a cranial mediastinal mass and a pleural effusion. A cytological examination of the pleural fluid showed that it did not contain neoplastic cells. A histological examination of an ultrasound-guided core biopsy of the cranial mediastinal mass showed that in each of the three horses it was a lymphosarcoma.     

Ultrasonographic findings in a cow with ascites due to thrombosis of the caudal vena cava.

This case report describes a three-year-old Swiss Braunvieh cow with ascites due to thrombosis of the caudal vena cava. Ultrasonography verified the ascites and revealed dilatation of the abdominal portion of the caudal vena cava (4.8 cm). It was presumed that the caudal vena cava was occluded by a thrombus or by perivenous compression cranial to the dilatation. Post mortem findings included: a massive accumulation of fluid in the abdominal cavity; a 15 cm long thrombus in the subphrenic region of the caudal vena cava; multiple pulmonary abscesses; severe thrombosis of the pulmonary vasculature; hepatic congestion; oedematous abomasal folds; and severe thrombophlebitis of the left jugular vein and both udder veins, due to poor intravenous injection technique. Ascites caused by thrombosis of the caudal vena cava is rare because collateral routes of venous return, including the udder veins, are usually established. It was therefore concluded that the ascites was attributable to bilateral thrombosis of the udder veins.     

The Great Vessels and Tributaries of the Heart of the Ringed Seal (Phoca hispida)

The ringed seal (Phoca hispida), as well as other seals, exhibit some unique anatomical properties when compared to their terrestrial counterparts. In the ringed seal, the most conspicuous adaptation is the aortic bulb, a large dilatation of the ascending aorta, which is comparable to that found in other seal species and marine mammals. Coronary arteries are similar to those of terrestrial mammals. The branches of the ascending aorta (brachiocephalic trunk, left common carotid artery and left subclavian artery) are similar to those of higher primates and man. The pulmonary trunk originates from the right ventricle near the ventral midline of the thorax. The peculiarities of the venous system are three pulmonary veins, a pericardial venous plexus, a caval sphincter, a hepatic sinus with paired caudal vena cavae and a large extradural venous system. Generally, three pulmonary veins (right, left, middle) empty into the left atrium. The right and left pulmonary veins drain the cranial and middle lung lobes of their respective lung, while the middle pulmonary vein drains both caudal lung lobes and the accessory lobe. The pericardial venous plexus lies on the pericardial pleura on the auricular (ventral) surface the heart. The azygous vein is formed from the union of right and left azygous veins near the 5th thoracic vertebra. The caval sphincter surrounds the caudal vena cava as it passes through the diaphragm. Caudal to the diaphragm, the vena cava is dilated excessively (the hepatic sinus) and near the kidneys it is biphid. Cardiovascular physiological studies have shown some of these anatomical variations, especially of the venous system and the ascending aorta, to be modifications for diving.     

Caudal vena caval thrombosis following treatment of deep digital sepsis

A diagnosis of caudal vena caval thrombosis was made by ultrasonography of a Holstein cow presented for lethargy and poor milk production. Medical treatment was unsuccessful and the cow was euthanized. The diagnosis was confirmed at necropsy and Fusobacterium necrophorum was isolated from the thrombus. This paper discusses potential novel sources of caval thrombosis in this case.     

Benign cranial mediastinal lesions in three cats

Cranial mediastinal lesions were detected in three cats, associated with respiratory impairment (case one), spontaneous pneumothorax (case two) and myasthenia gravis (case three), respectively. On gross and histological examination, the first case was considered either a lymphangioma or a branchial cystic mass of the thymic region of the mediastinum; a cystic lesion was suggested by sonographic detection of multiple anechoic cavitations within a circumscribed mass, while fine needle aspiration cytology excluded lymphosarcoma. The second case was diagnosed histologically as a cystic thymoma, but the third case was not examined microscopically. The masses were amenable to surgical excision in the first two cats, while this proved unnecessary in the third case because of resolution following treatment with dexamethasone. Corticosteroid responsiveness was unhelpful in distinguishing between these benign lesions and lymphosarcoma, as in two cases there was a partial or complete response to dosing with prednisolone or dexamethasone. These cases are presented to emphasise that conditions other than lymphosarcoma can produce cranial mediastinal lesions in cats, and that the prognosis for surgical treatment of lymphangiomas, multilocular thymic cysts and cystic thymomas can be excellent.     

Primary cranial mediastinal hemangiosarcoma in a young dog

Primary cranial mediastinal hemangiosarcomas are uncommon tumors. A 30-kg, 2-year-old, intact female German shepherd was presented for evaluation of cachexia and respiratory distress of a few days’ duration. Lateral radiographic projection of the thorax revealed significant pleural effusion. Computed tomography revealed a cranial mediastinal mass effect adjacent to the heart. On surgical exploration, a pedunculated mass attached to the esophagus, trachea, brachiocephalic trunk, left subclavian artery and cranial vena cava without attachment to the right atrium and auricular appendage was removed and debrided by use of blunt dissection and dry gauzes, respectively. Histopathology results described the cranial mediastinal mass as hemangiosarcoma. At 8 months and 5 days post-operatively, the patient died. Primary cranial mediastinal hemangiosarcomas, although a seemingly rare cause of thoracic pathology in young dogs, should be considered in the differential diagnosis for pleural effusion and soft tissue mass effect in the cranial mediastinum. This is the first case report in a dog to describe primary cranial mediastinal hemangiosarcoma.     

Central venous access to the cranial vena cava via the omobrachial vein in the dog

Background– The omobrachial vein is a superficial vein that crosses the brachial region of the dog. It terminates in the cranial vena cava, offering a novel site for central venous catheterization into the cranial thorax. Case Summary– The omobrachial vein served as a point of access to the cranial vena cava for treatment and monitoring of a critical canine patient in this report. The omobrachial vein was catheterized using the modified‐Seldinger technique due to contamination of or lack of availability of commonly used central venous catheter insertion sites. Conclusion– Access to the cranial vena cava via the omobrachial vein was easily achieved, and the catheter was maintained without complication for 10 days. Although the site was successfully used in the patient in this report, omobrachial vein anatomy is not consistent in all dogs.     

Clinical and Immunohistochemical Characterization of Thymic Lymphosarcoma in a Heifer

A 2–year-old Holstein heifer with a swollen brisket, jugular vein distention, muffled heart sounds, tachycardia, and free gas bloat was examined. Thymic lymphosarcoma was suspected based on a negative agar gel immunodiffusion test for bovine leukemia virus, presence of atypical lymphocytes in pleural fluid, and detection of a mass in the thoracic inlet. Right-sided cardiac catheterization was performed, and markedly increased jugular venous pressures (41 mm Hg) with a pressure gradient of 29 mm Hg immediately cranial to the heart indicated constriction of the cranial vena cava. Immunohistochemical staining of formalin fixed, paraffin-embedded tissue sections of the tumor using a rabbit anti-human T cell, CD3 polyclonal antibody confirmed that the neoplastic lymphocytes were of thymic origin. J Vet Intern Med 1996;275–278. Copyright © 1996 by the American College of Veterinary Internal Medicine .     

Catheterization of the caudal vena cava via the lateral saphenous vein in the ewe, cow, and gilt: an alternative to utero-ovarian and medial coccygeal vein catheters

Current methods for obtaining venous blood from the reproductive organs of livestock often have a low rate of success or involve intensive surgical procedures that may impair ovarian function. Therefore, the caudal vena cava was catheterized via the lateral saphenous vein to determine the feasibility of using this method for chronic sampling of blood draining from the reproductive organs of ewes (n = 6), cows (n = 6), and gilts (n = 7). Blood samples were collected at 2-cm (ewes and gilts) or 5-cm (cows) intervals during insertion of catheters. Correct placement, defined as the position at which plasma concentrations of progesterone or estrogen were at least threefold greater than in jugular venous plasma, varied among species and among animals within species. It seemed, however, that a majority of catheters would be placed correctly if secured at 48 to 52 cm in ewes, 52 cm in gilts, and 90 to 100 cm in cows. Saphenous vein catheters were secured for sequential sampling of vena caval blood during the follicular phase of ewes (n = 25), cows (n = 4), and gilts (n = 5). Catheters remained patent for the duration of sampling in all individuals. Concentrations of estrogen in jugular and vena caval plasma were correlated (ewe P less than .0003; cow P less than .0001; gilt P less than .0001). Profiles of progesterone and estrogen revealed an episodic pattern of secretion in vena caval but not jugular plasma. Catheterization of the vena cava via the saphenous vein is a relatively simple and noninvasive method for obtaining blood containing uterine and ovarian hormones before their metabolism.     

ACQUIRED PORTAL COLLATERAL CIRCULATION IN THE DOG AND CAT

We describe patterns of acquired portal collateral circulation in dogs and in a cat using multidetector row computed tomography angiography. Large portosystemic shunts included left splenogonadal shunts in patients with portal hypertension. Small portal collaterals were termed varices; these collaterals had several patterns and were related either to portal vein or cranial vena cava obstruction. Varices were systematized on the basis of the venous drainage pathways and their anatomic location, namely left gastric vein varix, esophageal and paraesophageal varices, gastroesophageal and gastrophrenic varices, gallbladder and choledocal varices, omental varices, duodenal varices, colic varices, and abdominal wall varices. As reported in humans and in experimental dog models, esophageal and paraesophageal varices may result from portal hypertension that generates reversal of flow, which diverts venous blood in a cranial direction through the left gastric vein to the venous plexus of the esophagus. Blood enters the central venous system through the cranial vena cava. Obstructions of the cranial vena cava can lead to esophageal and paraesophageal varices formation as well. In this instance, they drain into the azygos vein, the caudal vena cava, or into the portal system, depending on the site of the obstruction. Gallbladder and choledocal varices, omental varices, duodenal varices, phrenico-abdominal varices, colic varices, abdominal wall varices drain into the caudal vena cava and result from portal hypertension. Imaging plays a pivotal role in determining the origin, course, and termination of these vessels, and the underlying causes of these collaterals as well. Knowledge about these collateral vessels is important before interventional procedures, endosurgery or conventional surgery are performed, so as to avoid uncontrollable bleeding if they are inadvertently disrupted.     

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.