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

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.

Anatomicopathological Study of Vascular and Biliary Systems Using Cast Samples of Fasciola-infected Bovine Livers

In 117 livers with fascioliasis, this study was focused on the number of Fasciola, the number and intrahepatic localization of affected hepatic ducts and bile ducts, and the degree of fibrosis in the hepatic segments and bile ducts. The degree of pathological changes in bile ducts caused by fascioliasis was classified into five levels. The site of Fasciola habitation was most often the hepatic ducts of the porta hepatis: it was the left hepatic duct in 101 livers and the right hepatic duct in 88 livers. Casts were prepared by infusing synthetic resin into the hepatic arterial, portal, hepatic venous and biliary systems of 15 bovine livers with fascioliasis and then examined. In the left lobe, quadrate lobe, and caudate process where atrophic fibrosis was noted, the bile ducts became rod-shaped by losing branches, and the samples resembled dead branches of liver. Portal branches were thinned or completely terminated with marked fibrosis. Fine and irregular newly formed bile ducts not parallel with portal branches were observed in livers with markedly chronic fascioliasis. Distal portal branches in the right lobe, caudate lobe, and papillary process showed hypertrophic proliferative changes. The arterial system was generally well developed in thickened walls of bile ducts and formed vascular beds, and surrounded the bile ducts as tubes. In livers with severe fibrosis, capillaries were markedly developed and resembled glass cotton.

A review of nonconventional ultrasound techniques and contrast-enhanced ultrasonography of noncardiac canine disorders

Modern ultrasound contrast media are gas-containing stabilized microbubbles that remain intact in the circulating blood for several minutes after intravenous injection and increase the intensity of the backscattered ultrasound. When the microbubbles disappear from the blood, they can be detected in the parenchyma of the liver and the spleen for about 30 more minutes (late liver- and spleen-specific phase). The insonated microbubbles produce second harmonic ultrasound frequencies, whose detection requires nonconventional ultrasound modalities such as pulsed inversion imaging. Nonconventional ultrasound techniques can also be used without microbubbles because second harmonics can be generated by ultrasound in tissues as well. The physical principles and advantages of nonconventional ultrasound techniques are described. The circulating microbubbles can be used not only to enhance weak Doppler signals, but also to perform dynamic contrast studies. Contrast-enhanced dynamic ultrasound studies--similar to contrast-enhanced CT and MRI examinations--have been used in humans to characterize lesions noninvasively (i.e., without biopsies) found during conventional ultrasound examinations. To map the distribution of contrast medium in a nodule or in an organ, specific scanning techniques such as stimulated acoustic emission have been developed. Stimulated acoustic emission occurs when high acoustic pressure ultrasonic waves disrupt the stationary or slowly moving microbubbles. This results in the release of a large amount of harmonic ultrasound frequencies. When the stimulated acoustic emission technique is used for dynamic studies, scanning must be interrupted several times to allow the microvasculature of the lesion to refill with microbubbles (interval delay imaging). The contrast patterns of malignant and benign hepatic nodules in humans have been the most intensively studied. Another type of dynamic study in humans measures the transit time of the contrast medium; that is, how fast the peripherally injected microbubbles reach the hepatic veins. Hepatic cirrhosis can be differentiated from other diffuse parenchymal liver diseases by a shorter transit time. Introducing nonconventional ultrasound techniques and ultrasound contrast media in veterinary diagnostic imaging may have potential value; however, intensive research should be carried out before ultrasound contrast agents can routinely be used in clinical practice.

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.