Search

An 8 mo old male entire beagle was presented to the emergency and critical care service following several severe bleeding episodes from the oral cavity. Oral examination revealed a purple, spongy, pulsatile lesion on the rostral two-thirds of the tongue. Computed tomography angiography revealed a severely distended right linguofacial vein with numerous, tortuous branching vessels within the tongue, consistent with an arteriovenous (AV) malformation. A cervical surgical approach was performed, and the right lingual artery was isolated and catheterized. A direct arteriogram confirmed this was the main feeder artery to the lesion, and it was ligated. Although the bleeding episodes initially resolved, a moderate bleeding episode occurred 6 days postoperatively, and a partial glossectomy was performed. Histopathology was consistent with an AV malformation. The dog had a good recovery from surgery and remains free of clinical signs 13 mo later. Following extensive review of the veterinary literature, this is the only reported case of a lingual AV malformation in the dog. Partial glossectomy resulted in resolution of the clinical signs and was well tolerated. Although rare, AV malformations should be considered as a differential diagnosis for spontaneous oropharyngeal bleeding., (© 2020 by American Animal Hospital Association.)

Case Description: A 6-year-old 17-kg (37.4-lb) spayed female mixed-breed dog was evaluated because of swelling and intermittent lameness of the right pelvic limb and perianal and vulvar bleeding caused by a suspected arteriovenous malformation., Clinical Findings: The right pelvic limb had a diffuse, raised, cobblestone-like appearance with lameness, edema, and multifocal ulcerations. The abdominal skin had multifocal circular erythematous lesions, the perianal region was erythematous, and the vestibule had superficial distended vessels. Ultrasonography and CT did not reveal the presence of an arteriovenous malformation; however, digital subtraction venography confirmed the presence of a venous malformation (VM) throughout the limb., Treatment and Outcome: A mixture of foam sclerosant (1.5% sodium tetradecyl sulfate) and contrast medium was agitated with air and injected percutaneously into the VM. The dog received an injection of corticosteroid solution, and a soft-padded bandage was applied to the limb for 3 days. Six weeks later, the dog would intermittently hop when running, and the limb was mildly edematous with ecchymotic lesions; the swelling and lameness had improved considerably. Perianal and vulvar bleeding and dilation of the vestibular vessels had resolved. At 21 months after the procedure, examination revealed no right pelvic limb lameness related to the VM; only small cyst-like lesions and edema around the tarsus remained., Clinical Relevance: The favorable clinical outcome for this dog for a 21-month period after treatment of a pelvic limb VM with foam sclerotherapy has suggested that foam sclerotherapy may be used to successfully treat limb VMs in some dogs.

A four-year-old Japanese Akita was referred for investigation of lethargy, exercise intolerance, and an irregular heart rhythm. He was diagnosed with atrial fibrillation, a complex ventricular arrhythmia, and hypothyroidism. Echocardiography identified a nest of anomalous vessels surrounding the heart and shunting into the pulmonary artery. Computed tomography confirmed a coronary arteriovenous malformation consisting of a coronary-to-pulmonary arterial communication and an associated complex nest of tortuous vessels, which was thought to be an incidental finding. Clinical signs improved with levothyroxine and antiarrhythmic treatment. Describing an unusual coronary artery anomaly as well, this case serves as a reminder to critically evaluate the hemodynamic significance of structural cardiac disease and to screen for systemic disease in patients with arrhythmias., (Copyright © 2019 Elsevier B.V. All rights reserved.)

Arterioportal vascular anomalies are communications between the splanchnic arteries and the portal system that represent a rare cause of presinusoidal portal hypertension in small animals. There is little information concerning the imaging findings of arterioportal communications in small animals and no classification could be found for radiologists and surgeons. The aims of this retrospective descriptive multicentric study were to describe the computed tomographic characteristics of arterioportal communications in a group of cats and dogs, and to propose a classification based on computed tomography (CT) angiographic anatomy. Computed tomography databases from multiple veterinary hospitals were searched for cats and dogs with a diagnosis of arterioportal communication. A total of 36 animals (33 dogs, three cats) met the inclusion criteria. There were 32 intrahepatic arterioportal malformations and four extrahepatic fistulae. The intrahepatic arterioportal malformations were classified as right divisional (11/32) and left divisional (21/32), and the left divisional were subclassified as left medial (16/21) and left lateral (4/21). One patient showed multiple intrahepatic arterioportal communications with concomitant left medial and left lateral conformations. Two patients with intrahepatic arteriovenous malformation showed concomitant congenital intrahepatic shunts. The proposed anatomical classification based on CT angiography could allow veterinary radiologists to have a more systematic approach and help improve the radiologist-surgeon communication., (© 2018 The Authors. Veterinary Radiology & Ultrasound published by Wiley Periodicals, Inc. on behalf of American College of Veterinary Radiology.)

A 5-year-old neutered male Labrador retriever dog with a 3-year history of intermittent hemorrhage from the right metacarpal pad was evaluated. A small region of hyperattenuation of the metacarpal pad was evident on computed tomographic angiography. Excisional biopsy of the location of the purported hemorrhage revealed a micro-arteriovenous malformation on histologic examination.

CASE DESCRIPTION Two Pembroke Welsh Corgis with gastrointestinal signs including inappetence, diarrhea, lethargy, and hypersalivation were referred for evaluation. CLINICAL FINDINGS Diagnostic testing included abdominal ultrasonography and CT angiography. One patient had a cranial mesenteric artery-to-mesenteric vein fistula with multiple acquired extrahepatic portosystemic shunts. The second patient had both cranial and caudal mesenteric artery-to-mesenteric vein fistulas and multiple acquired extrahepatic portosystemic shunts. TREATMENT AND OUTCOME Both patients underwent minimally invasive coil embolization of the mesenteric arterioportal fistulas, with complete occlusion confirmed by means of angiography at procedure completion. Clinical outcome approximately 1 year after treatment was assessed as fair to good because of recurrence of clinical signs that required medical management in 1 dog and some persistent serum biochemical abnormalities. CLINICAL RELEVANCE Outcome for the 2 patients described suggested that coil embolization may be a feasible and effective minimally invasive technique for the treatment of mesenteric arterioportal fistulas in dogs. However, further investigation of the potential for chronic hepatic disease in patients with a history of acquired portosystemic shunts is warranted.

A 2-year-old male intact Belgian Malinois was presented for exercise intolerance. A grade III/VI left basilar systolic murmur was detected. Echocardiography revealed moderate right atrial and ventricular dilation and increased pulmonic outflow velocity. Thoracic radiographs showed right heart enlargement and a dilated caudal vena cava. In addition, on the left lateral projection, an enlarged aberrant right cranial pulmonary lobar vein was suspected to be diverging ventrally from the course of the right cranial lobar bronchus and inserting more ventrally than normal in the region of the right atrium. A left-to-right pulmonary vascular shunt was suspected, and the patient underwent further diagnostics under general anesthesia. An agitated saline study was positive, suggestive of a concurrent right to left shunt. A right heart catheterization was performed. Angiography was inconclusive. Oximetry testing revealed an increase in oxygen saturation within the right atrium at the level of the caudal cava supportive of a left-to-right shunt in this region. Computed tomography angiography revealed a large single pulmonary vein that anomalously entered into the caudolateral aspect of the right atrium (left-to-right shunt) and was suspicious for a small arteriovenous malformation between the right caudal pulmonary artery and the right pulmonary vein returning to the left atrium (right to left shunt). The patient was diagnosed with a partial anomalous pulmonary venous connection and a possible arteriovenous malformation., (Published by Elsevier B.V.)

CASE DESCRIPTION A 17-month-old neutered female Labrador Retriever with a 3- to 4-month history of abdominal distention was referred for evaluation and treatment. CLINICAL FINDINGS Evaluation of a peritoneal fluid specimen collected by the referring veterinarian indicated a pure transudate. At admission, transabdominal ultrasonography revealed microhepatica, dilation of the intrahepatic and mesenteric vasculature, peritoneal effusion, and multiple aberrant blood vessels. A large, high-flow hepatic arteriovenous malformation (HAVM) with secondary portal hypertension, peritoneal effusion, multiple acquired portosystemic shunts, and microhepatica was evident on CT angiography. TREATMENT AND OUTCOME Transfemoral hepatic arteriography and staged coil and glue (n-butyl cyanoacrylate) embolization of the complex arteriovenous malformation nidus and central main left hepatic artery resulted in ablation of the lesion, restoration of arterial blood flow to the contralateral hepatic lobes, and resolution of the peritoneal effusion. The dog remained without clinical signs of hepatic disease until it was euthanized 5 months after treatment for an unrelated condition. CLINICAL RELEVANCE Successful endovascular management of a HAVM was accomplished by means of coil and glue embolization in the patient of this report. Dogs with comparable HAVMs may benefit from similar minimally invasive treatment.

A 9-month old castrated male Labradoodle presented to the cardiology service at Purdue University for evaluation of a low-grade murmur. Physical examination, thoracic radiography, and echocardiography were strongly supportive of an extracardiac left-to-right shunt. Subsequent evaluation with nuclear scintigraphy and computed tomography angiography revealed a large, complex arteriovenous malformation within the cranial abdomen. Staged interventional attenuation of the shunt was performed using n-butyl cyanoacrylate that resulted in a reduction in echocardiographic and nuclear scintigraphy derived shunt estimation., (Copyright © 2017 Elsevier B.V. All rights reserved.)

A German shepherd puppy presented for evaluation of a suspected arteriovenous fistula on the distal aspect of the right pelvic limb. Radiographs demonstrated expansion and resorption of the tarsal and metatarsal bones, and ultrasound detected a vascular abnormality. Using computed tomographic angiography, a complex arteriovenous malformation (AVM) involving the distal tibia, tarsus, and the metatarsus and an osteochondritis dissecans (OCD) lesion of the talus were identified. Based on these findings, therapeutic limb amputation was performed. Fluoroscopic angiography, vascular casting, and dissection were then used to further characterize features of this previously unreported AVM with concurrent bony lesions and OCD., (© 2015 American College of Veterinary Radiology.)

Portosystemic shunting (PSS) often results in hyperammonaemia and, consequently, hepatic encephalopathy. This retrospective study evaluated the sensitivity, specificity, positive and negative predictive values (PPV and NPV, respectively) and other test performance metrics for the ammonia tolerance test (ATT), serum fasting bile acids (FBA), serum fasting ammonia concentration (FA), and combinations of these tests for their association with PSS in dogs. Medical records of 271 dogs suspect for PSS (symptomatic group) and 53 dogs returning for evaluation after surgical closure of a congenital PSS (CPSS post-surgical control group) were analysed. In the symptomatic group, ATT at 40 min (T40), and the FBA had the highest sensitivity (100% and 98%, respectively) and NPV (100% and 96%, respectively) for PSS. The combination of increased FBA and FA had the highest specificity (97%), with a PPV of 97%, and a positive likelihood ratio of 29. In the CPSS post-surgical control group, the specificity and PPV of FA and the combination of increased FBA/FA were both 100%. In purebred populations, the NPV of all tests was 100%. Consequently, PSS would be ruled out in a symptomatic dog with normal FBA or ATT (T40) and would be highly probable when both FBA and FA are increased. Increased FA was conclusive for PSS in dogs evaluated for post-surgical closure of a CPSS. FBA was the most suitable test for screening purposes., (Copyright © 2015 Elsevier Ltd. All rights reserved.)

Case Description: An 11-year-old castrated male Tibetan Mastiff was evaluated because of a visibly enlarged blood vessel and progressively worsening swelling of the right hind limb., Clinical Findings: On physical examination, the right hind limb was markedly larger than the left hind limb and the dog was minimally weight bearing on the affected limb. A bruit was auscultated over the affected region. Ultrasonography of the tarsal region of the right hind limb revealed an artery with turbulent flow that communicated with venous drainage. A CT scan confirmed the presence of an arteriovenous malformation (AVM)., Treatment and Outcome: Embolization of the AVM with a liquid embolic agent (ethylene-vinyl alcohol copolymer dissolved in dimethyl sulfoxide) was elected. An arteriogram was performed prior to treatment and delineated the vessels that were targeted for embolization. The embolic agent was infused into the AVM, and a postinjection arteriogram confirmed complete occlusion of the AVM nidus and normal arterial flow to the paw with subsequent normal venous drainage. The circumference of the abnormal paw was 51 cm before the procedure and 22.9 cm at 4 weeks after the procedure. Additionally, the gait of the dog dramatically improved. No complications associated with the procedure developed., Clinical Relevance: Peripheral AVMs in dogs are uncommon, and described treatment options are limited and generally associated with serious morbidity. A liquid embolic agent, ethylene-vinyl alcohol copolymer dissolved in dimethyl sulfoxide, was successfully administered in this case, and no morbidity was observed secondary to the procedure. Clinical success was characterized by substantial improvement in limb swelling and marked improvement in the gait of the dog.

Two cases of pulmonary vascular anomaly in unrelated adult alpacas (Vicugna pacos) are described. In the first case, a 9-year-old intact male alpaca presented at Oregon State University Veterinary Teaching Hospital with bilateral epistaxis and died the subsequent day following severe hemorrhage from the mouth and nostrils. At necropsy, a tortuous vascular lesion was identified in the right cranial lung lobe, associated with hemorrhage into airways. In the second case, a 2-year-old female alpaca presented with postpartum anorexia, opisthotonus, and recumbency. In this second case, a similar vascular lesion was identified in the right cranial lung lobe but without associated hemorrhage. Histopathological examination of the lesion in both cases revealed numerous dilated, irregular blood vessels with marked variation in wall thickness within vessels, surrounded by foci of extramedullary hematopoiesis. Diagnoses of locally extensive pulmonary vascular anomalies (arteriovenous malformations) were made.

A 9-year-old, female German Shepherd Dog presented with a firm bulging lesion at the tip of the tail. Histologically, the lesion was characterized by numerous poorly circumscribed clusters of vascular structures resembling capillaries that were separated by normal or mucinous connective tissues. The capillary-like vascular structures were composed of several layers: a single von Willebrand factor-positive endothelial cell layer with round, oval, or flattened hyperchromatic nuclei; and 1 or 2 surrounding spindle-shaped smooth muscle actin-positive pericyte layers. In the deep portion of the lesion, there were large vessels that showed morphological aberrations. These thin-to-thick-walled blood vessels corresponded to arteries and veins of varying diameters and were surrounded by fibrosis. The present case report describes a rare cutaneous vascular hamartoma, accompanied by aberrant arteriovenous structures.

Background: Portosystemic shunt (PSS) is the most common cause of hepatic encephalopathy in dogs and cats. Fasting ammonia and serum bile acids (SBA) are used to diagnose PSS, but their true sensitivity and specificity have not been fully evaluated, especially in cats., Objectives: The purpose of this study was to determine the diagnostic accuracy of fasting ammonia and SBA concentrations in the diagnosis of PSS in dogs and cats and to compare diagnostic accuracy between species., Methods: A retrospective analysis of data from 373 dogs and 85 cats presented to the clinic from 1996 to 2006 was carried out. Based on clinical, laboratory, and imaging findings, animals were grouped as having PSS, parenchymal hepatic disease, or extrahepatic disease. The sensitivity and specificity of ammonia and SBA concentrations for the diagnosis of PSS were calculated and receiver-operating characteristic analysis was used to optimize cut-offs., Results: Using the upper limit of laboratory reference intervals (ammonia, 59 micromol/L; SBA, 20 micromol/L), the sensitivity and specificity of ammonia was 85% and 86% in dogs, and 83% and 76% in cats, respectively. The sensitivity and specificity of SBA was 93% and 67% in dogs, and 100% and 71% in cats, respectively. Using optimal cut-off points for ammonia (dogs, 57 micromol/L; cats, 94 micromol/L) the sensitivity and specificity was 91% and 84% in dogs and 83% and 86% in cats, respectively. Using optimal cut-off points for SBA (dogs, 58 micromol/L; cats, 34 micromol/L) the sensitivity and specificity was 78% and 87% in dogs and 100% and 84% in cats., Conclusion: Increased fasting ammonia and SBA concentrations are accurate indicators of PSS. An improvement in diagnostic accuracy can be achieved by using defined optimal cut-off points for the selective diagnosis of PSS.

Three dogs presented for the evaluation of cardiac murmurs were diagnosed with aberrant arteriovenous shunts. All cases demonstrated the following findings: 1) relatively soft continuous murmur loudest at the left heart base resembling patent ductus arteriosus (PDA); 2) shunt flow signals in the pulmonary artery on echocardiography; and 3) no PDA on selective angiography, but evidence of anomalous shunting vessels from thoracic aorta to pulmonary vasculature. An aberrant arteriovenous shunt should be considered when a continuous murmur of relatively small intensity is heard.

Fever is not considered a typical clinical sign in animals with portosystemic vascular anomalies (PSVA). In a time period of 8 years, PSVA was diagnosed in 23 cases (20 dogs, 3 cats) at the Animal Hospital of the University of Zurich. Of these, recurrent fever was the only, the predominant or an early sign in 5 animals. Fever and associated unspecific clinical signs like lethargy, inappetence, and reluctance to move were present for weeks to months before the final diagnosis of PSVA was made. It was the lack of typical and well-known signs of PSVA that obscured and delayed the diagnosis. Therefore, PSVA should be included in the differential diagnosis of animals with fever of unknown origin (FUO).

A postprandial ammonia tolerance test (PPATT) was performed on normal dogs and dogs with signs that suggested they may have liver disease. All dogs underwent transcolonic scintigraphy, liver biopsy, or both and were assigned to extrahepatic disease, primary hepatocellular, and congenital portosystemic vascular anomalies (PSVA) groups. Each dog was fed a chicken and rice diet providing 25% of its estimated daily metabolizable energy requirement (MER) as an ammonia challenge. This is practical in patients with liver disease because ammonium chloride administration often causes vomiting or ammonia toxicity. Venous ammonia concentrations were measured before feeding and every 2 hours after feeding for 8 hours. No difference in mean ammonia concentrations between dogs with extrahepatic disease and control dogs was found. Therefore, the specificity of the PPATT was 100%. Dogs with hepatocellular disease showed no change in mean ammonia concentration at any time point, before or after feeding, but sensitivity was greatest when venous ammonia was measured 6 hours after feeding (sensitivity before feeding, 28%, and after feeding, 36%). Among dogs with congenital PSVA, mean ammonia concentrations were higher than the reference range at all time points before and after feeding, and peak mean ammonia concentration occurred 6 hours after feeding. In this group, the sensitivity of the PPATT was 81% before feeding and 91% 6 hours after feeding. This study demonstrates that the measurement of venous ammonia concentration is a useful test to detect congenital PSVA, and the sensitivity of the test may be improved by sampling 6 hours after feeding. The PPATT has poor sensitivity in detecting primary hepatocellular disease.

An 8-year-old female German Shepherd dog showed first order Horner's syndrome associated with progressive right-sided hemiplegia and mega-oesophagus. Intramedullary and leptomeningeal arteriovenous malformation (AVM) was identified in the cervical spinal cord. The morphological characteristics were arteriovenous shunting, intramedullary multiple thromboses and haemorrhage, non-inflammatory necrosis of white and grey matter around the shunt, and intervening neural gliosis with neovascularization. These findings suggested that the malformation induced a focal circulatory disturbance within the cervical spinal cord and that fatal thrombosis was responsible for the sudden onset of the nervous signs and progressive neurological deterioration. This is the first report of intramedullary spinal AVM in a dog., (Copyright 1999 W.B. Saunders Company Ltd.)

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.

Rectal bleeding in a 7-month-old 13-kg sexually intact female mixed-breed dog was determined to be associated with vascular ectasia of the small intestine, descending colon, rectum, and anus. Microscopically, the telangiectasia was associated with lymphangiectasia and focal ulceration. Surgical intervention resulted in incomplete resection of the lesion and only temporary amelioration of clinical signs. The dog's age was compatible with a congenital origin for the defect, but an acquired cause could not be excluded.

99mTechnetium-pertechnetate, when administered in high concentration into the colon, is rapidly absorbed across the colonic mucosa and results in a nuclear angiogram of the portal circulation. In normal dogs, a series of dynamic lateral scintigraphic images of the abdomen resulted in sequential visualization of the portal vein, liver, and several seconds later, the heart and lungs. In contrast, studies performed in 9 dogs with surgically confirmed portosystemic shunts demonstrated a different pattern of distribution, with heart and lung activity occurring before liver activity. In several cases, the aberrant shunt vessels could be identified. Studies were easy to perform, were well tolerated, and required no computer processing for interpretation.

Vascular malformations and angiomas are rather uncommon in horses and the literature concerning these lesions is reviewed. The pathology is described in 10 additional cases. These lesions were classified as arteriovenous malformation (one case), haemangiomas (six cases), 'proliferative angiomas' (two cases) and lymphangioma (one case). The haemangiomas and lymphangioma were probably hamartomatous in origin. Both cases of 'proliferative angioma' developed in aged animals and their pathogenesis was uncertain. More information is needed on the natural history and behaviour of lesions of this type.

The serum concentration of bile acids was measured in dogs and cats with portosystemic venous anomalies (PSVA). In 14 dogs, the mean serum bile acid concentration after 12 hours of fasting was 61.7 +/- 68.7 mumol/L (normal, 2.3 +/- 0.4 mumol/L (SEM) and when measured 2 hours after a meal in 15 dogs was 229.9 +/- 87.7 mumol/L (normal, 8.3 +/- 2.2 mumol/L). The fasting serum bile acid concentration was within the normal range in 5 of 14 dogs. The postprandial concentration was determined in 3 of the 5 and in each case increased more than tenfold above the fasting value. The mean fasting serum bile acid concentration in 4 cats was 24.4 +/- 10.1 mumol/L (normal, 1.7 +/- 0.3 mumol/L) and in 2 of the cats increased to a mean of 120.6 mumol/L (normal, 8.3 +/- 0.8 mumol/L) 2 hours after feeding. The bile acid values in patients with PSVA were correlated with values for blood ammonia content, sulfobromophthalein (BSP) retention, and results of conventional tests of hepatic function. Bile acid concentrations were more sensitive than abnormalities in serum enzyme activities or BSP retention and equal in sensitivity to the ammonia tolerance test in detecting hepatobiliary insufficiency. Bile acid measurements were accomplished with less inconvenience to the patient and clinician, than tests of BSP excretion or ammonia tolerance. Used in combination with conventional laboratory tests for hepatic disease, pre- and postprandial serum bile acid concentrations appear to be a sensitive and specific indicator of hepatobiliary dysfunction of value in the diagnosis of PSVA in the dog and cat.

An arteriovenous malformation and two hemangiomas in the canine spinal cord were found in three dogs. The malformation was ventral, extramedullary and largely subdural. Chronic hypoxia, consequent upon the shunt, had led to extensive local edema, necrosis and hemorrhage at T13-L1. Prominent intramedullary perivascular fibrosis, mineralization and obliteration were the presumed consequences of the hemodynamic insult. The hemangiomas, one of which was multiple, were deep lesions that produced compressive changes in the adjacent cord tissue. The masses were regarded as benign neoplasms with central sclerosis. These conditions appear not to have been reported previously in the dog.

A developmental arteriovenous malformation of the right arm was recognized in a 1-year-old rhesus monkey. The diagnosis was based on physical findings, ultrasound, and angiography. Treatment consisting of therapeutic transcatheter embolization using polyvinyl alcohol was performed with partial success. Necropsy revealed a lesion that was limited to the skin and subcutis. An abnormal vascular pattern was present leading to and within the lesion.

Three dogs were determined to have hepatic arteriovenous fistulas. This condition is similar to a portosystemic shunt; however, cure necessitates hepatic lobectomy instead of a venous ligature. Because of this, it is useful to differentiate these 2 conditions before surgery. Ultrasonography was found to be simple, sensitive, and specific in diagnosing hepatic arteriovenous fistulas and differentiating them from portosystemic shunts.