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.

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.

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.

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.

Surgical and Interventional Radiographic Treatment of Dogs with Hepatic Arteriovenous Fistulae

OBJECTIVE

To report outcome after surgical and interventional radiographic treatment of hepatic arteriovenous fistulae (HAVF) in dogs.

STUDY DESIGN

Retrospective study.

ANIMALS

Dogs (n=20) with HAVF.

METHODS

Medical records of dogs with HAVF were reviewed. Referring veterinarians and owners were contacted by telephone. History, clinical signs, biochemical and hematologic variables, ultrasonographic and angiographic findings, surgical findings, techniques used to correct the HAVF, survival time, and clinical follow-up were recorded.

RESULTS

Canine HAVF often appeared to be an arteriovenous malformation rather than a single fistula. Multiple extrahepatic portosystemic shunts were identified in 19 dogs. Surgery (lobectomy or ligation of the nutrient artery) and/or interventional radiology (glue embolization of the abnormal arterial vessels) was performed in 17 dogs. Thirteen dogs were treated by surgery alone, 4 dogs by glue embolization alone, and 1 dog by glue embolization and surgery. Three dogs treated by surgery alone died <1 month later, and 3 dogs were subsequently euthanatized or died because of persistent clinical signs. None of the dogs treated by glue embolization died <1month after the procedure and all were alive, without clinical signs, at follow-up (9-17 months). Overall, 9 of 12 (75%) dogs with long-term follow-up required dietary or medical management of clinical signs.

CONCLUSION

HAVF-related death occurred less frequently after glue embolization than after surgery.

CLINICAL RELEVANCE

Glue embolization may be a good alternative to surgery for treatment of certain canine HAVF.

Ultrasonographic diagnosis of unusual portal vascular abnormalities in two cats

Two cases of ascites secondary to portal vascular abnormalities associated with portal hypertension are described. In the first case a five-month-old cat was presented with recurrent ascites and investigations showed that the underlying cause was a hepatic arteriovenous fistula. Ultrasonography showed direct communication of the coeliac artery and right branch of the portal vein. There was also hepatofugal flow in the main portal vein consistent with portal hypertension. The ultrasonographic features were similar to those seen in dogs with hepatic arteriovenous fistulae. In the second case, ascites, portal hypertension and an intraluminal mass in the main portal vein was diagnosed in a 16-year-old cat that had been presented with hyperthyroidism and hepatomegaly. Acquired portosystemic collaterals involving the left renal vein were present. Additional diagnostic investigations were not permitted. Ultrasonography was useful in both cases to document portal hypertension and the underlying cause.

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.

Congenital Hepatic Arteriovenous Fistula with Intrahepatic Portosystemic Shunt and Aortic Stenosis in a Dog

Examination of a 2-month-old male golden retriever presented to the hospital revealed malnutrition, ascites, cardiac murmur and hyperammonemia. Identification of subaortic stenosis and hepatic arteriovenous fistula was made through ultrasonography and angiocardiography. In addition, intrasurgical mesenteric portography showed an intrahepatic portosystemic shunt. The dog did not show portal hypertension and secondary multiple extrahepatic portosystemic shunts. Surgical correction was attempted after medical treatment. The hepatic artery branch which was connected to the hepatic arteriovenous fistula was separated, and completely ligated using silk ligature. However, the separation of the intrahepatic shunt blood vessel was unsuccessful and the dog died 15 hr postoperatively.

Echo-Doppler findings of a carotid-jugular fistula in a foal

A seven-month-old male Standardbred was referred with a 4-month history of left jugular groove distension. On physical examination severely dilated left maxillary, linguofacial and jugular veins were appreciable. Blood gas analysis results indicated higher degree of oxygenation in the left jugular vein. Bi-directional flow signals, with normal systolic and early diastolic flow, and late diastolic retrograde flow, were noted on pulsed-wave Doppler interrogation and color flow mapping of the left jugular blood flow. A systolic-diastolic signal with spectral broadening was detected when positioning the sample gate near the internal jugular wall, in the distal left cervical region. Color Doppler imaging of the same region showed blood flow passage between the left common carotid artery and the left jugular vein through a small carotid-jugular fistula. Markedly increased blood flow velocities and volumetric flow, and decreased resistive index were recorded in the left compared to the right common carotid artery.

Cyanoacrylate occlusion and resection of an arteriovenous fistula in a cat

Arteriovenous fistula was diagnosed in a 6-year-old domestic shorthair cat 15 weeks after incurring a bite wound of the midportion of the right antebrachium. Arteriovenous shunting was confirmed by use of Doppler ultrasonography and nonselective fluoroscopic subtraction angiography Prior to resection, the fistula was embolized under fluoroscopic guidance with a mixture of cyanoacrylate glue and sterile iodinated contrast medium. Postoperative complications included pyrexia, local inflammation, and temporary neuropraxia. Cyanoacrylate embolization is a useful adjunct to surgical resection of peripheral arteriovenous fistulae.

Hepatic arteriovenous fistulae and portal vein hypoplasia in a Labrador retriever

An 18-month-old male Labrador retriever was referred for investigation of chronic intermittent diarrhoea and vomiting of two months duration. A diagnosis of hepatic arteriovenous fistulae was made. These are extremely rare hepatic vascular anomalies which confer arterial pressure to the portal vein. Liver atrophy, portal vein hypoplasia, portal hypertension and multiple acquired portosystemic collateral vessels are the main complications. Surgical excision is a challenge as resection of large lesions may be associated with significant blood loss. In this dog, persistence of portal vein hypoplasia and extensive collateral pathways following surgery led to a reserved prognosis.

Doppler ultrasonographic diagnosis and anatomy of congenital intrahepatic arterioportal fistula in a puppy

A dilated, tortuous blood vessel was identified sonographically in the right medial liver lobe in a puppy with severe ascites. This vessel was thought to represent the dilated right medial portal vein branch. Using pulsed wave Doppler ultrasonography, retrograde, abnormally pulsatile flow was detected in both the dilated right medial portal vein branch and the main portal vein. The right medial liver lobe was surgically resected then fixed in formalin. Silicon rubber was injected and outlined the connection between the portal vein and hepatic artery.

Ultrasonography of portosystemic shunts in dogs and cats

Ultrasonography is a rapid, accurate, noninvasive diagnostic test for primary (congenital) and secondary (acquired) portosystemic shunting in dogs and cats. Two-dimensional, gray-scale ultrasonography alone enables diagnosis of most congenital portosystemic shunts and determination of intra- versus extrahepatic location. Use of duplex- and color-flow Doppler ultrasonography aids detection of congenital and acquired extrahepatic portosystemic shunts. The underlying cause of acquired portosystemic shunting is portal hypertension; this may be documented by finding either hepatofugal or reduced velocity hepatopetal portal blood flow by duplex-Doppler. Also, ultrasonography may enable detection of lesions involved in the pathogenesis of portal hypertension, for example, hepatic arterioportal fistula, hepatic parenchymal lesions, and portal vein thrombosis.

Arteriovenous fistula involving the prepuce of a dog

A nine-year-old male Ibizan hound had a network of large tortuous pulsating blood vessels on the prepuce that enlarged gradually over a five month period. A diagnosis of arteriovenous fistula was based on clinical signs, angiography and Doppler ultrasonography. Ligation of the major vascular supply to the fistula resulted in only temporary improvement. Definitive treatment was by wide excision, with penile amputation and scrotal urethrostomy.

Congenital intrahepatic arteriovenous fistulae in a young beagle dog

Congenital intrahepatic arteriovenous fistulae, a rare hepatic vascular anomaly, in an 8-mo-old female beagle dog was investigated. The animal showed anorexia, repeated vomiting, hemorrhagic diarrhea, and jaundice for approximately 2 wk. There was mild to severe increase of serum alkaline phosphatase, glutamic-oxalacetic transaminase, glutamic pyruvic transaminase, total cholesterol, total bilirubin, and gamma-glutamyl transpeptidase. Macroscopically, the main abdominal organs showed hemorrhagic edema together with bloody ascites. Other characteristic findings were severe hepatic atrophy (right medial, quadrate, left medial, and lateral lobes) with multiple vascular cysts and compensatory hypertrophy of the other lobes. The cystic vessels seemed to extend from the proper hepatic arteries and their branches but were indistinguishable from the portal vein. Histopathologically, the atrophied hepatic lobes were characterized by wide, fibrous septa containing severe hyperplasia and anastomosis of the arteriolae and venulae and proliferation of bile ducts.

Computed tomography and magnetic resonance imaging of cavernous sinus enlargement in a dog with unilateral exophthalmos

Computed tomography (CT), magnetic resonance imaging (MRI) and magnetic resonance angiography (MRA) were performed on a dog with a two year history of unilateral exophthalmos occurring two years following head trauma. On CT images, an expansile enhancing mass was present along the right intracranial cavernous sinus and extended through the orbital fissure into the retrobulbar space. With MRI, the structure appeared as a signal void due to the presence of rapidly flowing blood. Gadolinium enhancement of the adjacent brain was not present. A vascular origin of the lesion was confirmed with MRA. Based on the CT and MRI findings, the enlarged cavernous sinus and associated ophthalmic plexus were believed to represent an arterialized aneurysm, most likely the result of traumatic arteriovenous fistulization. Treatment consisted of surgical enucleation. At the time of this report, 29 months later, the dog remains free of clinical signs.

Suspected microscopic hepatic arteriovenous fistulae in a young dog

Portal hypertension can develop from any disorder that obstructs portal blood flow and may cause ascites in young dogs. Anomalous hepatic arteriovenous (AV) connections are rare but should be suspected in any young dog with portal hypertension or ascites. All previous reports of dogs with hepatic AV fistulae have documented macroscopic connections between the arterial and venous systems. Identical clinical signs and histopathologic findings can develop in dogs in which a macroscopic hepatic AV connection cannot be detected. Microscopic AV connections may be responsible for clinical signs in these dogs.

Technetium 99m sulfur colloid scintigraphy to evaluate reticuloendothelial system function in dogs with portasystemic shunts

In a retrospective study, technetium 99m sulfur colloid scintigraphy was used to evaluate reticuloendothelial system function in 61 dogs with single congenital and 40 dogs with multiple acquired portasystemic shunts. Whole body reticuloendothelial function was measured by calculating the plasma clearance rate constant from a dynamic study of liver uptake of 99mTc sulfur colloid. Relative liver, spleen, and lung uptake, and a ratio of hepatic:extrahepatic uptake were measured on static equilibrium images. Results were compared with those of a group of 26 normal dogs. Compared with values for the group of normal dogs, the plasma clearance rate constant, relative liver uptake, and hepatic:extrahepatic uptake ratio were significantly decreased, and relative spleen and lung uptake were significantly increased in dogs with portasystemic shunts (P < .0001). The only significant difference between dogs with single congenital versus multiple acquired shunts was that the relative splenic uptake was higher in the former group (P < .0002). Based on these results, we concluded that dogs with portasystemic shunts have significantly impaired reticuloendothelial function. The primary cause of this dysfunction is likely a reduction in effective liver blood flow. Increases in spleen and lung reticuloendothelial activity did occur, but only partially compensated for the reduction of liver reticuloendothelial activity. Possible mechanisms for the increased spleen and lung uptake are discussed.

Vascular pattern of a metastatic liver tumor in a dog:--a scanning electron microscopic study of resin casts

Metastasis of a malignant mixed tumor occurring in the abdominal wall was found in the liver of a 15-year-old dog male. The vascular system of the metastatic lesion was examined by scanning electron microscopy using the resin cast technique. The existence of arterio-portal shunts was confirmed. The shunts arose from branches of the hepatic artery in retrograde or vertical direction and merged into the capillary plexus replacing the branches of the portal vein, forming the so-called thread and streaks vessel in the field of hepatic angiography. Vessels with the thread and streaks appearance histologically represented tumor emboli growing in the lumen of a large branch of the portal vein. There were capillaries running inside along the portal vein and forming a longitudinal dense network in the vein. Branches of the hepatic artery feeding the metastatic lesion were well developed and formed a coarse arterial network in their course. Tributaries of the hepatic vein from the lesion were also well developed.

Arteriovenous fistula of the jejunum associated with gastrointestinal hemorrhage in a dog

Hemorrhage from the gastrointestinal tract of a young dog resulted in melena with concurrent anemia. Exploratory laparotomy revealed the hemorrhage originated from an arteriovenous fistula in the jejunum. Resection of the abnormal part of the jejunum was curative. The arteriovenous fistula in the dog was probably congenital in origin, but may have been the result of gastrointestinal tract trauma.

Acquired arteriovenous fistula secondary to castration in a dog

A 6-year-old castrated male Basset Hound was examined because of a 1-year history of a pulsating mass in the right inguinal region. The pulsatile mass was diagnosed as an arteriovenous fistula by physical examination and angiography. Surgical exploration revealed that the right testicular artery and vein, the artery of the ductus deferens, and the cremasteric artery were involved in the fistula. The fistula was believed to have developed secondary to castration performed at 6 months of age. The mass and associated vessels were completely excised and signs of recurrence were not observed 13 months after surgery.

Pulsed spectral Doppler evaluation of a peripheral arteriovenous fistula in a horse

Pulsed spectral Doppler ultrasonography was used to characterize the vascular involvement and anatomic boundaries of a peripheral arteriovenous fistula on the hemithorax of a horse. This information facilitated surgical removal of the fistula. Pulsed spectral Doppler evaluation of suspected peripheral vascular anomalies should be considered for the diagnosis of similar lesions, in which contrast angiography is not possible.

Lameness in a mare with signs of arteriovenous fistula

A 5-year-old mare was evaluated for lameness and swelling of the right forelimb. Clinical findings, including peripheral edema, venous pulsation, palpable thrill in the cephalic vein, disparate arteriovenous oxygen tension differences between the left and right forelimbs, and Branham sign, were suggestive of arteriovenous fistula. Failure to identify the fistula by angiography was attributed to closure of the shunt during anesthesia. Surgical exploration of the affected limb to identify the shunt also was unsuccessful.

Hepatic lesions associated with intrahepatic arterioportal fistulae in dogs

Seven cases of hepatic arterioportal fistulae in young dogs (mean age 6 months) are described. All cases were presumed to be congenital in origin. The onset of clinical signs, which frequently included gastrointestinal and neurological disturbances, was usually sudden. All dogs had clinical evidence of portal hypertension in the form of ascites, and all developed multiple extrahepatic portacaval venous shunts consequential to portal hypertension. The neurological disturbances were likely the result of portacaval shunting. The arterial and venous vessels involved in the fistulae had markedly altered wall structure. Hepatic regions adjacent to the fistulae frequently evidenced marked bile duct proliferation. Hepatic parenchymal atrophy, relative collapse of distributing portal veins, dilatation of hepatic arterial branches and proliferation of hepatic arterioles were seen throughout the liver; these changes closely resembled those present with portacaval shunting in the absence of hepatic arterioportal fistulae. The importance of recognizing that hepatic arterioportal fistulae and multiple extrahepatic portacaval shunts usually coexist and separately influence the morphological appearance of the liver is stressed.

Iatrogenic arteriovenous fistula in a cynomolgus macaque (Macaca fascicularis): a case report

A juvenile male cynomolgus macaque was slightly depressed and had a rough haircoat. Cardiomegaly and pulmonary interstitial edema were found. A distinct fremitus was palpable over the right femoral canal. The only abnormal laboratory finding was an elevated total leukocyte count. A femoral arteriogram confirmed the diagnosis of femoral arteriovenous fistula. Surgical correction of the fistula was successful in reversing the heart failure. The history and anatomic location of the lesion suggested an iatrogenic cause.

Acquired peripheral arteriovenous fistula in a dog

A pulsating mass with a continuous bruit was discovered in a dog's flank during routine examination. Based on a history of trauma and clinical signs, an acquired arteriovenous (AV) fistula and a false aneurysm were included in the differential diagnosis. Arteriography confirmed the presence of an AV fistula and outlined the lesion for successful surgical extirpation. Hsitopathologic characteristics of the AV fistula were similar to those in man.

A case of spermatic arteriovenous anastomosis in the horse

A large anastomosis of the spermatic artery and vein is described. This was found while surgically removing an abdominal testis. Before surgery the animal wanted to rear after exercise and could not stand on 3 legs for any length of time while being shod. This unusual behaviour disappeared after removal of the mass. The performance and conformation of the horse has also greatly improved.

Ascites associated with intrahepatic arteriovenous fistula in a cat

A 1 1/2-year-old male domestic short-haired cat with ascites was found to have an intrahepatic fistula between the hepatic artery and portal vein. The diagnosis was made by means of angiography. The ascites was attributed to portal hypertension caused by the fistula.

Hepatic arteriovenous fistula in two Saint Bernard pups

Two saint bernard pups, 7 and 5 months old respectively, were examined because of anorexia, vomiting, and ascites. Exploratory laparotomy disclosed arteriovenous fistula of the right medial lobe of the liver in one dog, and in the right medial and quadrate lobes of the other one. Surgical removal of the affected lobes resulted in cessation of presenting signs. Both dogs remained healthy but had poor weight gain and vomited occasionally. After more than 2 years of apparently good health, both dogs were euthanatized and necropsied because of presumably unrelated gastrointestinal disturbances.

Absence of arteriovenous anastomoses in anesthetized sheep

Microspheres, approximately 50 µ in diameter and labeled with scandium 46, were injected into the jugular vein in three sheep and into the left ventricle in one. Radioactivity was recovered only from the lungs after jugular injections. After left ventricular injection, the fraction of radioactivity recovered from the lungs corresponded closely to the proportion of cardiac output carried by the bronchial circulation. It appears that no physiologically significant arteriovenous anastomoses exist in sheep under the experimental condition.