Spinal epidural arteriovenous fistula in 3 cats.

Three young adult cats with intermittent spinal hyperesthesia and paraparesis and diagnosed with spinal epidural arteriovenous fistula are described. In all 3 cases, magnetic resonance imaging (MRI) showed focal dilatation of the veins in the epidural space of the thoracic spinal cord, whereas computed tomography angiography (CTA) showed dilatation and enhancement from the intercostal vein to the azygos vein at the same site in the arterial phase. Dorsal laminectomy and occlusion of the interarcuate branches running across the dorsal aspect of the spinal cord were performed in all 3 cats to decompress the spinal cord, which resulted in a remission of clinical signs and no recurrence during 14 to 40 months of follow-up after surgery in all cases.

Peripheral arteriovenous fistula manifesting as antebrachial dermatopathy in a cat.

CASE DESCRIPTION A 13-year-old neutered male Abyssinian cat with a 4-month history of right forelimb edema and multifocal crusting lesions at the distal aspect of the antebrachium was referred to a veterinary teaching hospital for evaluation. Extensive hemorrhage from the lesions had been observed after self-grooming, and findings on histologic examination of a skin biopsy sample prior to referral were consistent with atypical dermal hemodynamics and inflammation. CLINICAL FINDINGS Diffuse pitting edema and multifocal, 3- to 4-mm-diameter sanguineous crusting lesions affecting the antebrachium were observed distal to a pulsatile subcutaneous mass in the right elbow joint region that had a palpable thrill and auscultable bruit. No systemic abnormalities were detected. TREATMENT AND OUTCOME Contrast-enhanced CT angiography with 3-D reconstruction identified an arteriovenous fistula with a large aberrant vessel coursing distally. Surgical ligation of an arterialized vein distal to the fistula without en bloc resection led to resolution of all clinical signs. The vascular anomaly was no longer patent when diagnostic imaging was repeated 5 months after surgery. CLINICAL RELEVANCE Acquired arteriovenous fistulas can lead to bleeding skin lesions affecting the antebrachium in cats. Surgical ligation of an aberrant reverse-shunting vein distal to the fistula successfully resolved clinical signs in the cat of this report and may warrant investigation as a treatment option in cats with this condition.

Surgical management of a cat with hepatic arterioportal fistula.

A 9-month-old domestic short-haired cat presented with stunted growth and chronic gastrointestinal signs. Tachypnoea, a heart murmur and cranial abdominal bruit were detected on physical examination. Echocardiography revealed volume overload in all heart chambers. CT angiography identified an abnormal communication between the hepatic arterial circulation and the portal vein, along with multiple acquired shunts. The abnormal vascular communication was surgically ligated. Echocardiography documented improvement in cardiac parameters following surgery and the cat continues to have no clinical signs 39 months after surgery. This report describes successful surgical management of feline hepatic arterioportal fistula for the first time.

CT features of extrahepatic arterioportal fistula in two cats.

Two cats presented with large volume ascites and the cause was suspected to be portal hypertension. On contrast CT they both showed enhancement of the main portal vein during the arterial phase and an anomalous connection between the celiac artery and extrahepatic portal vasculature, prompting a diagnosis of extrahepatic arterioportal fistula. An extrahepatic arterioportal fistula is a connection between any artery and the portal vein outside the liver and, to our knowledge, this is the first report in cats.

Clinical, echocardiographic and advanced imaging characteristics of 13 dogs with systemic-to-pulmonary arteriovenous fistulas.

OBJECTIVES: The objective is to describe the clinical, radiographic, echocardiographic and angiographic findings in dogs with systemic-to-pulmonary arteriovenous fistula (SPAVF). ANIMALS: Thirteen medical records of client-owned dogs with a diagnosis of SPAVF were reviewed/analysed. METHODS: This is a retrospective study of case records. Thoracic radiography, transthoracic echocardiography (TTE), transesophageal echocardiography (TEE), three-dimensional TEE, intracardiac echocardiography, fluoroscopy-guided or computed tomography (CT) angiography were carried out. RESULTS: Based on the TTE, SPAVF was identified in seven of the included dogs. In eight cases, TEE and angiography were both performed and confirmed the diagnosis. Computed tomography angiography was performed in three dogs. A case was diagnosed by TEE alone, another one by three-dimensional TEE and the latter by intracardiac echocardiography. CONCLUSIONS: Transthoracic echocardiography identified seven cases of SPAVF, while definitive diagnosis in the remaining dogs required selective angiography or computed tomography angiography.

Pseudoaneurysm and Arteriovenous Fistula in a Rhesus Macaque (Macaca mulatta).

An 8-y-old female rhesus macaque (Macaca mulatta) presented for swelling of the left lower limb distal to the inguinal region and associated with the femoral artery. Physical and ultrasound examinations suggested an arteriovenous fistula combined with a pseudoaneurysm. After review of possible treatment options, we determined that open surgical repair was the best course of action. The pseudoaneurysm and arteriovenous fistula were surgically resected, and the macaque recovered without complication.

Triple-phase helical computed tomography of an arterio-hepatic venous shunt in a hepatic tumor in a dog.

A 10-year-old French bulldog presented with an abdominal tumor. Triple-phase helical computed tomography was performed, revealing a hepatic tumor, an enlarged hepatic lymph node, and no masses in other organs. The hepatic tumor demonstrated marked enhancement, similar to that of the aorta in the arterial phase. The tumor had rich vascularization and a hepatic arterio-venous shunt formed between the hepatic artery and middle hepatic vein. The hepatic tumor was surgically removed and histological diagnosis revealed a hepatic carcinoid tumor. During surgery, rapid massive arterial hemorrhage occurred from the site of the incision. The animal died without improvement post-surgery. In the case of an arterio-venous shunt in a hepatic tumor, it is important to be careful to avoid perioperative bleeding.

Computed tomographic and angiographic assessment of spinal extradural arteriovenous fistulas in a dog.

A 6-month-old German shepherd dog was presented for progressive paraparesis. Multiple arteriovenous fistulae and hyperostosis of the thoracic vertebrae with secondary thoraco-lumbar spinal cord compression were diagnosed. Arteriovenous spinal fistula is a rare condition but should be considered as a differential diagnosis in young dogs with progressive paraparesis.

Évaluation par tomodensitométrie et angiographie de fistules artérioveineuses extradurales spinales chez un chien. Un chien Berger allemand âgé de 6 mois a été présenté pour une paraparésie progressive. De nombreuses fistules artérioveineuses et de l'hyperostose des vertèbres thoraciques avec une compression de la colonne vertébrale thoraco-lombaire secondaire ont été diagnostiquées. Les fistules spinales artérioveineuses sont une rare affection mais elles devraient être considérées comme un diagnostic différentiel chez les jeunes chiens atteints de paraparésie progressive.(Traduit par Isabelle Vallières).

Congenital Extrahepatic Abdominal Arteriovenous Fistula and Apparent Patent Ductus Venosus in a Dog.

A 3 mo old male German shepherd dog presented with a 2 wk history of diarrhea with possible melena followed by inappetence and progressive abdominal distension. Clinical findings, serum biochemical analysis, and abdominal ultrasound were highly suggestive of an extrahepatic abdominal arteriovenous fistula and concurrent patent ductus venosus, which were confirmed during an abdominal exploratory surgery. Renal biopsies taken at the time of surgery confirmed a chronic glomerulopathy. The dog made a good initial recovery from the procedure but was euthanatized 6 wk postoperatively for medically unresponsive renal disease.

MULTIDETECTOR-ROW COMPUTED TOMOGRAPHY PATTERNS OF BRONCHOESPHAGEAL ARTERY HYPERTROPHY AND SYSTEMIC-TO-PULMONARY FISTULA IN DOGS.

Anomalies involving arterial branches in the lungs are one of the causes of hemoptysis in humans and dogs. Congenital and acquired patterns of bronchoesophageal artery hypertrophy have been reported in humans based on CT characteristics. The purpose of this retrospective study was to describe clinical, echocardiographic, and multidetector computed tomography features of bronchoesophageal artery hypertrophy and systemic-to-pulmonary arterial communications in a sample of 14 dogs. Two main vascular patterns were identified in dogs that resembled congenital and acquired conditions reported in humans. Pattern 1 appeared as an aberrant origin of the right bronchoesophageal artery, normal origin of the left one, and enlargement of both the bronchial and esophageal branches that formed a dense network terminating in a pulmonary artery through an orifice. Pattern 2 appeared as a normal origin of both right and left bronchoesophageal arteries, with an enlarged and tortuous course along the bronchi to the periphery of the lung, where they communicated with subsegmental pulmonary arteries. Dogs having Pattern 1 also had paraesophageal and esophageal varices, with the latter being confirmed by videoendoscopy examination. Authors conclude that dogs with Pattern 1 should be differentiated from dogs with other congenital vascular systemic-to-pulmonary connections. Dogs having Pattern 2 should be evaluated for underlying pleural or pulmonary diseases. Bronchoesophageal artery hypertrophy can be accompanied by esophageal venous engorgement and should be included in the differential diagnosis for esophageal and paraesophageal varices in dogs.

Unilateral shunt formation with thoracic aortic dissection in a whippet.

A three-year-old neutered male whippet was presented with intermittent, exercise-induced paraparesis. Femoral pulses were bilaterally absent. Neurologic examination was suggestive of a thoracolumbar myelopathy. Blood pressure measurements revealed hypotension in both pelvic limbs, hypertension in the right thoracic limb and it was immeasurable in the left thoracic limb. Echocardiography was within reference limits. A clear vascular pulsation was palpable on the right ventral abdominal wall. Computed tomographic angiography revealed a dissection of the aortic wall between the left subclavian artery and the brachiocephalic trunk with subsequent thrombus formation. A shunt between the right internal thoracic, cranial and caudal epigastric arteries to preserve blood flow to the pelvic limbs was visualized. Necropsy was declined by the owner. This is the first case report describing the formation of a unilateral vascular shunt following a thoracic aortic occlusion, which presented as exercise-induced paraparesis.

Surgical correction of an arteriovenous fistula in a ring-tailed lemur (Lemur catta).

A 10-y-old ovariohysterectomized ring-tailed lemur (Lemur catta) was presented for exacerbation of respiratory signs. The lemur had a history of multiple examinations for various problems, including traumatic lacerations and recurrent perivulvar dermatitis. Examination revealed abnormal lung sounds and a femoral arteriovenous fistula with a palpable thrill and auscultable bruit in the right inguinal area. A diagnosis of congestive heart failure was made on the basis of exam findings, radiography, abdominal ultrasonography, and echocardiography. The lemur was maintained on furosemide until surgical ligation of the fistula was performed. Postoperative examination confirmed successful closure of the fistula and resolution of the signs of heart failure. Arteriovenous fistulas are abnormal connections between an artery and a vein that bypass the capillary bed. Large arteriovenous fistulas may result in decreased peripheral resistance and an increase in cardiac output with consequent cardiomegaly and high output heart failure. This lemur's high-flow arteriovenous fistula with secondary heart failure may have been iatrogenically induced during blood collection by prior femoral venipuncture. To our knowledge, this report is the first description of an arteriovenous fistula in a prosimian. Successful surgical correction of suspected iatrogenic femoral arteriovenous fistulas in a cynomolgus monkey (Macaca fascicularis) and a rhesus macaque (Macaca mulatta) have been reported previously. Arteriovenous fistula formation should be considered as a rare potential complication of venipuncture and as a treatable cause of congestive heart failure in lemurs.

Recruitment of arteriovenous pulmonary shunts may attenuate the development of pulmonary hypertension in dogs experimentally infected with Angiostrongylus vasorum.

OBJECTIVES: The purposes of this study were to evaluate if (1) Angiostrongylus vasorum-infected dogs recruit pulmonary arteriovenous (AV) shunts attenuating the development of pulmonary hypertension (PH), detectable using saline contrast echocardiography, (2) anthelmintic therapy causes an acute increase in pulmonary arterial pressure (PAP), (3) Tissue Doppler Imaging (TDI) allows detection of mild changes in right ventricular function secondary to pulmonary (vascular) disease. ANIMALS: 6 healthy Beagle dogs, each infected with 200 A. vasorum larvae. METHODS: Conventional, TDI and contrast echocardiography, invasive PAP measurements before (T0), 7-12 weeks post infection (wpi, T1), and 1-5 days post therapy (dpt, T2). RESULTS: All dogs had patent infections 7-8 wpi and respiratory signs 6-9 wpi. PAP was mildly but significantly increased at T2. Saline contrast echo was positive in 3/6 dogs at T1 and 4/6 dogs at T2. Pulmonary transit time did not change. Of all numeric echocardiographic parameters, only a non-significant decrease in the E' wave and inversion of E'/A' ratio in 3 dogs at T2 could be observed. Two of these had mild PH and negative saline contrast echocardiography. CONCLUSION: A. vasorum infection causes only a mild increase in PAP following inoculation and anthelmintic therapy. The absence of important PH may in part be explained by the recruitment of AV shunts in the presence of vascular obstructive disease. TDI echocardiographic parameters may be more sensitive to detect mild changes in RV function than conventional parameters.

Coil embolization of an aorticopulmonary fistula in a dog.

An 8-year-old, castrated male Basset Hound was evaluated for congestive heart failure and atrial fibrillation. Echocardiography and angiography demonstrated a left-to-right shunting aorticopulmonary fistula. Coil embolization of the fistula was initially successful in reducing the volume of blood flow through the vascular network. The dog was medically managed for congestive heart failure until it was euthanized 6 months after initial presentation. The physiology and treatment of centrally located arteriovenous fistulae are discussed.

Acquired arteriovenous fistula in a grizzly bear (Ursus arctos horribilis).

A captive adult male grizzly bear (Ursus arctos horribilis) was evaluated due to multifocal wounds of the skin and subcutaneous tissues sustained as a result of trauma from another grizzly bear. On presentation, one lesion that was located in the perineal region seemed to be a deep puncture with purple tissue protruding from it. This perineal wound did not heal in the same manner or rate as did the other wounds. Twenty-five days after initial detection, substantial active hemorrhage from the lesion occurred and necessitated anesthesia for examination of the bear. The entire lesion was surgically excised, which later proved curative. An acquired arteriovenous fistula was diagnosed via histopathology. Arteriovenous fistulas can develop after traumatic injury and should be considered as a potential complication in bears with nonhealing wounds.

Post-traumatic peripheral arteriovenous fistula manifesting as digital haemorrhages in a cat: diagnosis with contrast-enhanced 3D CT imaging.

Arteriovenous fistulae (AVF) are defined as congenital or acquired abnormal direct communications between an artery and a vein leading to abnormal blood circulation. This report describes an unusual manifestation of acquired peripheral AVF in a cat for which the diagnosis was confirmed by computed tomographic (CT) imaging and three-dimensional (3D) reconstruction. A 10-year-old female spayed domestic shorthaired cat was presented with a 2-month history of nonhealing, crusting, erosive and ulcerative skin lesions on the dorsal right forepaw. Severe chewing and biting, but not lameness, had been reported. Systemic abnormalities were not noted. Histopathology revealed increased numbers of thin-walled and slightly grouped vascular profiles in the superficial and mid-dermis, which were often markedly dilated and partially obscured by prominent hyaline deposits. There were a few pyknotic nuclear fragments and haemorrhages in vascular walls as well as multifocal luminal thrombosis with or without recanalization. Differential diagnoses included progressive angiomatosis with trauma or AVF with secondary regional venous hypertension. Computed tomographic images were acquired using a 16-slice Siemens Somotom Sensation CT scanner, and 3D images were created using the Voxar 3D software. Image reconstruction revealed tortuous aberrant vasculature on the medial aspect of the radius and around the carpus compared to normal vascularization on the contralateral limb. These changes were suggestive of the diagnosis of acquired peripheral AVF. The differential diagnosis for localized, nonhealing, haemorrhagic, crusted, erosive or ulcerative distal extremity skin lesions in cats should include acquired AVF, and diagnosis may be confirmed with contrast-enhanced CT imaging.