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.     

Cranial vena caval thrombosis secondary to invasive mediastinal lymphosarcoma in a cat

A 12-year-old female cat was diagnosed with a cranial vena caval thrombosis in association with a mediastinal lymphosarcoma. The cause of the cranial vena caval thrombosis was thought to be invasion of the venous wall by neoplastic lymphoid cells. Clinical signs of cranial vena caval thrombosis, such as swelling and oedema of the submandibular area, the ventral part of the neck and the forelimbs, were related to a space-occupying mediastinal lymphosarcoma, which also induced respiratory distress and cyanosis. Non-selective angiocardiography demonstrated the occlusion of the cranial vena cava and abnormal venous collateral vessels feeding the heart which are accepted as the venographic hallmark of clinically overt cranial vena caval syndrome. At postmortem examination, an intracaval thrombus, 5 cm in length, was seen extending from the costocervical vein to the sulcus terminalis of the right atrium.     

IMAGING DIAGNOSIS—AORTIC THROMBOEMBOLISM ASSOCIATED WITH SPIROCERCOSIS IN A DOG

An 8-year-old neutered female Rhodesian Ridgeback developed acute, nonneurological right pelvic limb lameness. Femoral pulsation was poor, and oscillometric blood pressure measurements between the two pelvic limbs differed markedly. A caudal aortic right external iliac embolus was detected sonographically. Radiographically, there was a caudal esophageal mass and thoracic vertebral spondylitis typical of spirocercosis. Using CT-angiography, a caudal thoracic aortic aneurysm with a mural thrombus was detected. The dog recovered following heparin and aspirin therapy but signs recurred 7 months later. Subsequently, the patient improved on treatment and remains asymptomatic. This report illustrates the value of CT-angiography in detecting aortic thrombosis in dogs with spirocercosis.     

Clinical and Pathological Features of Aortic Thromboembolism in 36 Dogs

Thirty-six dogs with aortic thromboembolism were identified in a retrospective study conducted using case material from the small animal necropsy service of the University of Pennsylvania, from 1977 through 1992. No age, breed, or sex predisposition was found. Thirty dogs presented with primary complaints referable to the aortic thromboembolus and the duration of signs varied from hours to months. In 16 dogs, the presence of the thromboembolus was confirmed antemortem by ultrasound or angiography. Coagulograms were performed in 11 animals, and were consistent with consumptive hemostatic disorders in 8. The aortic occlusions were determined to be emboli in 11 dogs, associated with cardiac disease (9 dogs) and neoplastic emboli (2 dogs). In 18 dogs, the aortic occlusions were determined to be caused by primary aortic thrombi. Nine of these dogs had renal disease and four dogs had severe atherosclerosis associated with thyroid disease. In seven dogs, it could not determined if the aortic occlusions were due to primary aortic thrombi or due to emboli. In 25 dogs, the aorta was the only vessel occluded; but in 11 dogs, thrombi were identified in vessels outside of the systemic arterial system. In 9 dogs, the pulmonary arteries contained thromboemboli; one dog had thrombi in the portal vein and pulmonary arteries, and one dog a cranial vena caval thrombus. Nine of 11 dogs with multiple vascular thrombi, as well as some of the dogs with primary aortic thrombi, may have had either a propensity for thrombosis (a hypercoagulable state) or an inability to lyse thrombi (a hypothrombolytic state).     

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.     

In vitro ultrasonographic appearance of the normal and verminous equine aorta, cranial mesenteric artery, and its branches

Ninety-one equine aortic and cranial mesenteric arterial segments were evaluated ultrasonographically in a water bath. On the basis of pathologic evidence of verminous arteritis, arterial segments were classified into 4 categories, and the ultrasonographic characteristics of each group were evaluated. Normal arteries (class 1) were ultrasonographically characterized by a smooth luminal surface layer and uniform wall thickness and echogenicity. Arteries with only histopathologic evidence of verminous arteritis (class 2) were ultrasonographically characterized by a smooth luminal surface layer, uniform hyperechoic luminal layer. Arteries with both gross and histopathologic evidence of verminous arteritis (class 3) were characterized ultrasonographically by an irregular luminal surface layer, varying wall thickness, varying wall echogenicity, and the presence of a hyperechoic luminal layer. The ultrasonographic characteristics of arteries with luminal thrombosis (class 4) were an irregular luminal surface, varying wall thickness, and nonuniform echogenicity.     

Unusual vascular ring anomaly associated with a persistent right aortic arch in two dogs

An unusual vascular ring anomaly consisting of a persistent right aortic arch and a left ligamentum arteriosum extending from the main pulmonary artery to an aberrant left subclavian artery and left aortic arch remnant complex was identified in a German shepherd dog and a great Dane. The left subclavian artery and left aortic arch remnant complex originated at the junction between the right distal aortic arch and the descending aorta and coursed dorsal to the oesophagus in a cranial direction. The attachment of the ligamentum arteriosum to the aberrant left subclavian artery was approximately 5 cm cranial to the point of origin of the aberrant left subclavian artery and left aortic arch remnant complex from the descending aorta in both dogs. This anomaly observed in both dogs is similar to an anomaly reported in humans, in which a persistent right aortic arch is found in conjunction with an aberrant left subclavian artery and a left aortic arch remnant (Kommerell's diverticulum). Surgical ligation and division of the left ligamentum arteriosum in both dogs, along with division of the left subclavian artery in the great Dane, resulted in resolution of clinical signs in both of the dogs in this report.     

Left Cranial Vena Cava in a Horse

A complete left cranial vena cava (LCVC) was found in a normal horse. The LCVC was well developed, but there was a complete absence of the right cranial vena cava. The azygous vein was normally distributed on the right side of the thoracic vertebral bodies but passed ventral to the aortic arch to empty into the cranial vena cava on the left close to the origin of the aortic arch. The LCVC passed over the dorsal aspect of the left atrium to reach the coronary sulcus on the caudal aspect of the heart. The LCVC opened into the right atrium via a 5 cm diameter orifice (orifice of coronary sinus). The vena cordis magna joined the LCVC 6 cm from the orifice of the coronary sinus. Complete dissection of the horse revealed no other developmental abnormalities. This case is compared with similar cases in the literature.     

Thrombosis of the cranial vena cava in a cow with bronchopneumonia and traumatic reticuloperitonitis

This paper reports the clinical findings, surgical and medical management, and necropsy of a 6-year-old cow with thrombosis of the cranial vena cava and thrombo-embolic pneumonia following traumatic reticuloperitonitis. The clinical diagnosis was confirmed by necropsy.     

Technique for transrectal ultrasonography of the cranial mesenteric artery of the horse

Transrectal ultrasonography was successfully used to image the cranial mesenteric artery and its branches in 23 adult horses. The artery could be imaged from its origin at the aorta distally to identify several bifurcations. The method for transrectal imaging of the cranial mesenteric artery and its major branches required 3 distinct transducer positions. One position was used to locate the cranial mesenteric artery by imaging the caudal portion of the aorta from the aortic bifurcation cranially to the level of the cranial mesenteric artery. The second position was used to image the origin of the cranial mesenteric artery. The third position was used to image the major branches of the cranial mesenteric artery.     

Double aortic arch in a dog (Canis familiaris): a case report

We herein report a case of a double aortic arch in a 10-week-old male dog of no defined race, which presented episodes of regurgitation at the time of weaning. This vascular malformation was characterized by the persistence of two aortic arches, right and left, of varying dimensions. The right aortic arch was observed to be larger. During post mortem examination the vessels of the animal were injected with coloured latex bi-centrifuged CIS 1-4 polisopreno which revealed the patency of the two aortic arches. Concomitantly, dilation of the cranial oesophagus causing constriction was observed, indicating megaesophagus. Apart from the constriction, the oesophagus presented normal morphometric parameters in relation to its dimensions.     

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.     

En block resection of a large hepatocellular carcinoma involving the caudal vena cava in a dog

A 13-year-old neutered female Shih Tzu was referred for investigation of a cranial abdominal mass. Investigations including conventional radiography, abdominal ultrasonography and computed tomography confirmed the mass in the caudate lobe of the liver. As a collateral vein originating from the caudal vena cava (CVC) communicated with the azygos vein, the CVC was ligated and transected cranial to the right renal vein and cranial to the mass under temporary occlusion of the thoracic descending aorta and posthepatic CVC. The mass combined with the CVC was excised. The mass was confirmed as hepatocellular carcinoma (HCC). This report describes the first case with successful en bloc resection of a large HCC involving the CVC in a dog.     

IMAGING DIAGNOSIS—ARTERIAL AND VENOUS THROMBOSES OF THE PROXIMAL LIMB IN TWO THOROUGHBRED RACEHORSES

Thromboses of the cranial tibial vein (Horse 1) and brachial, median, and cranial circumflex humeral arteries (Horse 2) were identified as causes of unilateral lameness in two Thoroughbred racehorses. Nuclear scintigraphy was performed for suspicion of long bone stress fractures but instead allowed identification of unusual areas of increased radiopharmaceutical uptake within soft tissues of the affected limbs. Ultrasonography of these regions allowed identification of occlusive thrombi within a 25 cm length of the cranial tibial vein (Horse 1) and variable lengths of affected arteries in Horse 2. Horse 1 developed secondary infections and was euthanized. Staphylococcus aureus was isolated from all sites. The cause of thrombosis was not identified in Horse 2.     

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.     

Symmetrical double aortic arch in a beagle puppy

Double aortic arch denotes the persistence of both fourth aortic arches and has been reported as 'very rare' in the dog. Most reported cases have been seen in German shepherd dogs. An eight-week-old, male, 1.5-kg beagle presented with a three-week history of regurgitation and dyspnoea. A barium oesophagram showed severe oesophageal constriction cranial to the base of the heart, and a provisional diagnosis of a persistent right aortic arch was made. A left-sided fourth intercostal thoracotomy was performed. The ligamentum arteriosum was ligated and divided. The oesophagus was seen lying on the right-hand side of the aorta. Postoperatively, the puppy deteriorated and was euthanized. Postmortem revealed a double aortic arch entrapping both the oesophagus and trachea. The inexperienced surgeon could consider computed tomography or angiography to determine the exact vascular ring, and other possible concurrent vascular anomalies present, before surgery.     

MINERALIZED ARTERIOSCLEROSIS IN A CAT

In radiographs of a domestic short haired cat of unknown age, mineralization was identified in the pulmonary parenchyma, peripheral pulmonary vessels, the aortic outflow tract, aortic valve, celiac artery, cranial mesenteric artery, and the internal and external iliac arteries. The diffuse arterial mineralization was characterized histopathologically as arteriosclerosis. This is the first report of mineralized arteriosclerosis in a cat with corresponding radiographic signs. The arteriosclerosis is thought to be due to systemic hypertension but a definitive cause for the profound mineralization was not found. Causes of soft tissue mineralization are reviewed.     

Evaluation of the Cranial Rectus Abdominus Muscle Pedicle Flap as a Blood Supply for the Caudal Superficial Epigastric Skin Flap in Dogs

This study evaluates the cranial rectus abdominus muscle pedicle flap as the sole blood supply for the caudal superficial epigastric skin flap. This flap was composed of a cranially based rectus abdominus muscle pedicle flap that was attached to the caudal superficial epigastric island skin flap (including mammary glands 2 to 5) via the pudendoepigastric trunk. Selective angiography of the cranial epigastric artery in eight cadaver dogs proved that the arterial vasculature in the cranial rectus abdominus was contiguous with that in the caudal superficial epigastric skin flap. In the live dog study, three of six of the flaps failed because of venous insufficiency. Necrosis of mammary gland 2 occurred in two of six flaps. One of six flaps survived with the exception of the cranial most aspect of mammary gland 2. Angiography of the cranial epigastric artery proved that arterial blood supply to these flaps was intact. Histological evaluation of the failed flaps showed full-thickness necrosis of the skin and subcutaneous tissues, the presence of severe congestion, and venous thrombosis. Retrograde venous blood flow through the flap was inconsistent, and hence resulted in failure of this myocutaneous flap. Use of this flap for clinical wound reconstruction cannot be recommended.     

Double aortic arch and persistent left vena cava in a white lion cub (Panthera leo).

A 4-mo-old female white lion (Panthera leo) cub was presented with a 2-wk history of persistent postprandial regurgitation, mild dyspnea, and poor weight gain. The cub was weak and thin but otherwise alert. Survey and contrast radiography revealed a large dilated esophagus cranial to the heart base, with an esophageal filling defect present at the level of the fourth thoracic vertebra. A vascular ring anomaly was tentatively diagnosed. Exploratory thoracotomy revealed a double aortic arch and a persistent left vena cava. The left aortic arch was ligated and divided, and recovery was uneventful. A single episode of regurgitation occurred within the first postoperative month, and the cub gained 5.5 kg in weight during the same time period. Neither double aortic arch nor persistent left vena cava has been reported in a nondomestic felid.     

RECOMMENDATIONS FOR STANDARDS IN TRANSTHORACIC TWO-DIMENSIONAL ECHOCARDIOGRAPHY IN THE DOG AND CAT*

Recommendations are presented for standardized imaging planes and display conventions for two-dimensional echocardiography in the dog and cat. Three transducer locations (“windows”) provide access to consistent imaging planes: the right parasternal location, the left caudal (apical) parasternal location, and the left cranial parasternal location. Recommendations for image display orientations are very similar to those for comparable human cardiac images, with the heart base or cranial aspect of the heart displayed to the examiner's right on the video display. From the right parasternal location, standard views include a long-axis four-chamber view and a long-axis left ventricular outflow view, and short-axis views at the levels of the left ventricular apex, papillary muscles, chordae tendineae, mitral valve, aortic valve, and pulmonary arteries. From the left caudal (apical) location, standard views include long-axis two-chamber and four-chamber views. From the left cranial parasternal location, standard views include a long-axis view of the left ventricular outflow tract and ascending aorta (with variations to image the right atrium and tricuspid valve, and the pulmonary valve and pulmonary artery), and a short-axis view of the aortic root encircled by the right heart. These images are presented by means of idealized line drawings. Adoption of these standards should facilitate consistent performance, recording, teaching, and communicating results of studies obtained by two-dimensional echocardiography.