Sage Journals: Discover world-class research

Abstract

Practical relevance:

Abdominal ultrasound plays a vital role in the diagnostic work-up of many cats presenting to general and specialist practitioners. Although hepatic vascular anomalies are less common than disorders of the hepatic parenchyma and biliary tree, our understanding and recognition of these is gradually increasing with advancements in ultrasound technology and image quality.

Clinical challenges:

Despite ultrasonography being a commonly used modality, many practitioners are not comfortable performing an ultrasound examination or interpreting the resulting images. Even differentiating between normal variation and pathological changes can be challenging for all but the most experienced. In addition, some views may be obscured by overlying structures; for example, the termination of a shunt entering the left phrenic or azygous veins is often difficut to see due to the high probability of lung passing between the shunt and the transducer as the cat breathes.

Equipment:

Ultrasound facilities are readily available to most practitioners, although use of ultrasonography as a diagnostic tool is highly dependent on operator experience.

Aim:

This review, part of an occasional series on feline abdominal ultrasonography, discusses the appearance of various hepatic vascular anomalies. It is aimed at general practitioners who wish to improve their knowledge and confidence in feline abdominal ultrasound and is accompanied by high-resolution images. Ultrasound of the liver and biliary tree were discussed in articles published in January and May 2019, respectively.

Evidence base:

Information provided in this article is drawn from the published literature and the author’s own clinical experience.

Keywords

Ultrasound hepatic vascular anomalies portosystemic shunt splenosystemic shunt arteriovenous fistula portal vein thrombosis

Compared with disorders of the hepatic parenchyma and biliary tree, hepatic vascular anomalies are somewhat less common in the cat. However, as ultrasound technology and image quality continue to improve and our understanding of vascular abnormalities grows, recognition of these disorders is gradually increasing.

Portosystemic shunts

Portosystemic shunts (PSSs) are abnormal vascular connections between the portal system and systemic venous circulation that allow blood to bypass the liver.⁴ They may be congenital or acquired, the former being more common in cats.

Congenital portosystemic shunts

Although congenital PSSs are a well-recognised cause of hepatic encephalopathy, they occur far less commonly in cats than in dogs.⁵ The use of ultrasonography for the diagnosis of PSSs in both species has been described in detail and only features pertinent to cats are discussed here.^6-11 For further information regarding the expected laboratory results, options for surgical management and prognosis in cats with a congenital PSS, readers are referred to two earlier reviews in JFMS by Tivers and Lipscomb.^12,13

Congenital PSSs have been reported in both domestic shorthair cats, which account for the majority of cases, and purebred cats, particularly Siamese, Himalayans, Burmese and Persians.^5,6,12,14-17 While the majority of cats are presented for investigation of a suspected shunt when less than 12 months of age,^6,18 shunts can remain undetected for many years.^12,17 Cats with congenital shunts can be normal in size and stature or small and in poor condition, and often present with neurological signs.^5,6,15,17

Congenital shunts can be subdivided into those that are located outside the liver (extrahepatic) and those located inside the liver (intrahepatic).

Congenital extrahepatic shunts

Single extrahepatic shunts are more common in cats than intrahepatic shunts, although both have been reported.^9,6,17,19,20 Extrahepatic shunts in cats can be divided into five subtypes: left gastrophrenic, left gastrocaval, splenocaval, left gastroazygous and those arising from the left colic vein, with the first three accounting for 92% of shunts in this species (see box below for imaging guidelines and interpretation).^22,23

A shunt arising from the left gastric vein is recognised on ultrasound as a large vessel entering the gastrosplenic vein from a cranial direction, usually close to where the latter enters the main portal vein. The shunt, which is often tortuous in nature, can sometimes be followed to its termination in the left phrenic vein, pre- or post-hepatic caudal vena cava (CVC) or azygous vein. In cats with a left gastrophrenic shunt (by far the most common subtype), the anomalous shunting vessel enters the left phrenic vein at the level of the oesophageal hiatus.^22,24 It may be possible to follow the dilated left phrenic vein with ultrasound as it travels lateromedially along the caudal surface of the diaphragm before entering the post-hepatic CVC.²⁴ In cats with a left gastrocaval shunt, the anomalous vessel enters the post-hepatic CVC at the level of the caval foramen, often via a saccular dilation or ampulla, which may be recognised ultrasonographically.²⁴ As mentioned in the box above, in those cats with a splenocaval shunt, the shunting vessel terminates in the pre-hepatic CVC at the level of the epiploic foramen.^24,26 Local disruption to flow resulting in turbulence may be noted in the cava at the site of entry of a shunt (Figure 3).

Figure 1

To image the portal vein starting at the confluence of the cranial and caudal mesenteric veins, the transducer is placed on the right flank with the cat in left lateral recumbency

Figure 2

Colour Doppler ultrasound image depicting normal flow in the portal and gastrosplenic veins. The blue colour in the portal vein confirms that the direction of blood flow is from caudal to cranial (ie, hepatopetal), or from right to left in this image. The red colour in the gastrosplenic vein is consistent with flow towards the transducer and thus flow into the portal vein

Figure 3

Ultrasound image showing altered flow within the caudal vena cava at the level of shunt entry. A colour flow Doppler window has been applied over the cava. In the right side of the window, flow in the cava is depicted as being blue, indicating that flow is away from the transducer and therefore from right to left (or caudal to cranial) in the image, as expected. In the left side of the window, the solid blue colour has been replaced with a mosaic of several colours including red, yellow, blue and cyan. According to the colour map on the left side of the image, this indicates that flow is directed both towards and away from the transducer, which is the typical appearance of turbulence

The presence of a large diameter vessel adjacent to the aorta in the craniodorsal abdomen, containing cranially directed blood flow, is consistent with a left gastroazygous shunt.⁹ It should be noted that the normal azygous vein is not seen on ultrasound in cats.¹⁰ It is often difficult to see the termination of a shunt entering the left phrenic or azygous veins due to their inherently cranial location within the abdomen and the high probability of lung passing between the shunt and the transducer as the cat breathes.

The left colic vein is a tributary of the caudal mesenteric vein. Shunts arising from the left colic vein can be identified on ultrasound by the presence of a large vessel containing hepatofugal flow that enters a distended caudal mesenteric vein (Figure 4).²³ An interesting feature of left colic shunts is that they often travel caudally before making a 180° turn to enter the systemic venous circulation via either the CVC or common iliac vein.²³

Figure 4

Ultrasound images from a 5-month-old male entire domestic longhair cat with an extrahepatic shunt originating from the left colic vein and terminating in the caudal vena cava (CVC). (a) Image acquired at the level of the confluence of the cranial and caudal mesenteric veins. The diameter of the shunting vessel is much greater than that of the portal vein (PV). (b) Colour Doppler image at the same level as (a) shows abnormal hepatofugal flow in the portal vein cranial to the shunt and within the shunting vessel itself, as denoted by the arrows. As the shunt was followed caudally (c,d), it formed a large, tortuous vessel containing hepatofugal flow (ie, directed from left to right in the images). (e) Focal dilation of the CVC (arrows) at the entry site of the shunt

Congenital intrahepatic shunts

As previously stated, intrahepatic shunts occur less commonly than extrahepatic shunts in the cat. Most intrahepatic shunts in cats are left divisional, although both right- and central-divisional shunts have also been reported.¹⁸ Ultrasound can be used preoperatively to accurately characterise intrahepatic shunts as left, right or central divisional.¹⁸

As in the dog, left-divisional shunts in cats are thought to represent a patent ductus venosus and arise from the left branch of the intrahepatic portal vein, forming a large-diameter vessel, initially travelling cranio-laterally through the left side of the liver before coursing medially to drain into the CVC via the left hepatic vein.^18,27 Right-divisional shunts in the cat can similarly present as a large tortuous vessel but are located within the right side of the liver, rather than the left.²⁷ In dogs, central-divisional shunts are usually formed from a foramen between the intrahepatic portions of the portal vein and CVC, whereas in the cat they take the form of a tortuous intrahepatic vessel.²⁷ The use of a right or left craniodorsal intercostal and/or subcostal approach is often necessary to identify the intrahepatic shunt ultrasonographically.⁹

The ability to identify and follow any shunting vessel will depend not only on operator experience but also on patient cooperation and the extent of any gas within the gastrointestinal tract, which can obscure important anatomy. Therefore, while the ‘shunt hunt’ can be performed with the patient conscious, it is often preferable to use sedation.

Figure 5

Medullary rim sign (arrows) in the kidneys of a 4-month-old female entire cat with a left gastrocaval portosystemic shunt. A medullary rim sign is a hyperechoic band within the medulla that parallels the corticomedullary junction

Figure 6

Ammonium urate uroliths (arrows) present within the urinary bladder (same cat as Figure 5). The hyperechoic interface and strong distal acoustic shadowing are typical of mineralised calculi

Acquired portosystemic shunts

Acquired shunts are pre-existing embryonic vessels that open up and dilate in response to chronic portal hypertension to allow blood to bypass the liver and enter the systemic circulation directly. The prevalence of acquired portosystemic shunting in cats as a result of portal hypertension is low and only occasional reports exist.^35-42 This may be at least in part attributable to the relatively low prevalence of cirrhosis in this species, which is a common cause of acquired shunts in the dog.³⁹ Acquired shunts have been reported to occur in cats in association with several conditions including hepatic fibrosis,^39,41 arterioportal fistulae,^37,43 portal vein thrombosis³⁷ and chronic diaphragmatic herniation,⁴⁰ and also as a sequela to surgical attenuation of a congenital PSS.^44,45

Although reports of the ultrasonographic appearance of secondary acquired shunts in cats are also rare, acquired shunt morphology appears to mirror that seen in dogs. Acquired shunts can take the form of one or more plexuses of small tortuous vessels in the retroperitoneal space close to one or both kidneys or between the portal vein and CVC (Figure 7).^39,40 A peritoneal effusion of variable volume is also commonly found in cats with acquired PSSs.³⁹

The presence on ultrasound of an acquired shunt taking the form of a solitary abnormal vessel containing hepatofugal flow that originated from the portal vein close to the splenic vein has also been described in two cats with clinical signs of hepatic encephalopathy.⁴¹ In both cases, liver histology revealed congenital hepatic fibrosis, a condition that arises due to congenital biliary cystic lesions and has previously been linked with polycystic kidney disease in cats.⁴⁶ The authors of the case report concluded that the congenital liver disease most likely resulted in portal hypertension and the formation of acquired portosystemic collaterals.⁴¹

Figure 7

(a,b) Colour flow Doppler images showing the typical ultrasonographic appearance of acquired shunts that have formed secondarily to portal hypertension. Small vessels such as these are usually best appreciated with colour flow Doppler and can be surprisingly difficult to identify in B-mode grey scale images

Splenosystemic shunts

A separate category of shunt that has been described in predominantly older, spayed female cats is the splenosystemic shunt.⁴⁷ It is thought that splenosystemic shunts most likely represent either acquired shunts resulting from previous or current portal hypertension or they are congenital shunts of uncertain clinical significance.⁴⁷

On ultrasound, a splenosystemic shunt usually takes the form of a single anomalous vessel that originates from the splenic vein and follows a tortuous course either caudal to the left kidney before entering the left renal vein or CVC adjacent to the renal vein, or continues medial to the left kidney. In some cats, while the shunt may start and end as a single vessel, it can also form a plexus of smaller vessels at some point along the way. Of 33 cats with a splenosystemic shunt identified using ultrasound, 42% also had a hepatopathy that could potentially have resulted in portal hypertension.⁴⁷ Three cats had hepatopetal portal flow with a flow speed <10 cm/s and one cat had hepatofugal portal flow, suggestive of portal hypertension. Ascites was also identified in 10 cats.

Splenosystemic shunts have additionally been observed in abdominal radiographs of cats and create what is now referred to as a ‘spaghetti sign’.⁴⁸ The typical radiographic appearance is that of a well-defined, tortuous, tubular structure of soft tissue opacity within the left mid-abdominal cavity, lateral to the left kidney and caudal to the spleen.⁴⁸

Figure 8

Selected transverse plane computed tomography angiography (CTA) images of the abdomen of a 4-month-old domestic shorthair cat with an extrahepatic left gastrophrenic portosystemic shunt. All images are displayed in a soft tissue window (window level 40; window width 440), were acquired following the administration of iodinated intravenous contrast and are presented in caudal-to-cranial order. The patient’s right-hand side is to the left of the image. (a) Within the cranial abdomen, the portal vein (PV) is visible in the normal location ventral to the caudal vena cava (CVC), just to the right of midline. (b) A short distance cranial to this, the gastrosplenic vein joins the PV from the left (not shown). A large vessel (the shunt) emerges from the gastrosplenic vein at the expected location of the left gastric vein and is located to the left of the PV at this level. Note that the shunt is much larger in diameter than the PV. (c,d) The shunting vessel travels cranially and slightly dorsally within the abdomen, medial to the gastric fundus. (e,f) At the level of the diaphragm, the shunt joins with the left phrenic vein, which runs along the abdominal side of the diaphragm before draining into the post-hepatic CVC. Additional findings identified in the same CTA study included microhepatica and urolithiasis. GB = gall bladder; Ao = aorta

Portal vascular abnormalities

Arterioportal fistulae

An intrahepatic arterioportal fistula is an abnormal communication between a hepatic artery and a portal vein within the liver and can be congenital or, less commonly, acquired.⁴² Intrahepatic arterioportal fistulae are extremely rare in the cat and only three cases have been reported to date.^37,42,43 The ultrasonographic appearance appears to be very similar to that seen in dogs with the same condition (Figure 9).^37,42,53 All three cats were 18 months of age or younger at the time of diagnosis.

Figure 9

(a) Ultrasound image of a large tortuous vessel representing a congenital arterioportal fistula in the liver of a 4-month-old Golden Retriever puppy. The vessel could be traced from the coeliac artery to the point where it joined the left branch of the portal vein. (b) Colour flow Doppler confirms the presence of blood flow within the vessel, which in this case is directed towards the transducer. (c) In a different region of the liver, a plexus of multiple tiny vessels is present within the hepatic parenchyma below the fistula. These were barely visible on B-mode grey scale images. The gall bladder is visible in the bottom right of the image. (d) Colour flow and pulsed-wave Doppler interrogation of the portal vein shows that flow is hepatofugal (ie, away from the liver), turbulent, pulsatile and travelling at a higher speed than normal. (e) Multiple loops of a dilated anomalous blood vessel within the liver of a 2-month-old Labrador Retriever puppy that also had a congenital arterioportal fistula. (f) Single slice transverse plane computed tomography angiography image through the cranial abdomen of the same dog as in (e). The image is displayed in a soft tissue window (window level 40; window width 440) and was acquired following the administration of iodinated intravenous contrast. Multiple loops of a large tortuous vessel representing an arterioportal fistula are observed within the cranial abdomen (asterisks) and liver. Throughout the abdomen, numerous plexuses of much smaller tortuous vessels are present, consistent with the formation of secondary acquired shunts. A moderate volume of peritoneal fluid is also visible and likely to be the result of portal hypertension

Abdominal ultrasonography was performed on two cats and in both cases revealed ascites and dilation of an intrahepatic portal vein branch containing turbulent pulsatile flow on colour Doppler images.^37,42 In one of the cats, an enlarged coeliac artery could be followed with ultrasound from its origin at the aorta to its communication with the dilated portal vein branch.³⁷ Doppler interrogation of this cat revealed hepatofugal pulsatile flow of abnormally high speed within the main portal vein, which was dilated.³⁷ Portal flow with these characteristics can be explained by the presence of high-pressure arterial blood flowing into the low-pressure portal system, increasing pressure in the latter and ultimately resulting in portal hypertension. Acquired PSSs arising secondarily to portal hypertension and involving the left renal vein were also identified in both cats.^37,42

Portal vein aplasia

Portal vein abnormalities are uncommon in the cat. A single case of congenital absence of the portal vein has recently been reported in a 9-month-old female neutered domestic shorthair cat. While this was suspected on abdominal ultrasound, CTA was necessary for confirmation of the diagnosis.⁵⁴

Figure 10

Echogenic thrombus (arrows) obstructing the portal vein of a 4-year-old male neutered Siamese cat with lymphoma

Portal vein thrombosis

Thrombosis of the portal vein can result from vascular stasis, damage to the vessel endothelium or a hypercoagulable state and is a rare cause of portal hypertension in the cat.⁵⁵ To date, only seven cases of portal vein thrombosis in cats have been reported in the literature.^37,56 Six had evidence of hepatobiliary disease and the remaining cat had raised liver enzymes and hyperthyroidism.^37,56 Abdominal ultrasonography was performed in all seven cases. In five cats, the portal vein thrombus had an echogenic appearance on ultrasound, and in the sixth cat reduced blood flow was identified in the renal, splenic and portal veins.⁵⁶ In the remaining cat, a hypoechoic mass, presumed to be a thrombus, was identified within the main portal vein;³⁷ the mass completely filled the lumen of the portal vein and caused mild focal dilation of the vessel. In four of these cats, colour flow Doppler was also used to confirm reduced or absent flow within the portal vein thrombus, and in two cats small plexuses of tortuous vessels, representing secondary acquired shunts, were visible in the region of the portal vein or left kidney.^37,56

Thrombi vary in echogenicity depending upon their age and this could explain the variation in appearance of the portal vein thrombi described in these cats. A recently formed thrombus can appear almost anechoic and may be missed without the use of colour flow Doppler.⁵⁷ A chronic thrombus, on the other hand, is more likely to be visible with B-mode ultrasound due to its echogenic appearance relative to blood (Figure 10).⁵⁷

Key Points

Extrahepatic portosystemic shunts are more common than intrahepatic shunts in cats. The majority arise from the left gastric vein and are best appreciated using a right flank or intercostal window.

Most intrahepatic shunts in the cat are left divisonal and form a large tortuous vessel that runs through the left side of the liver and drains into a hepatic vein.

Acquired shunts are rare in the cat, but when they do occur they often take the form of a retroperitoneal plexus of tiny vessels that directly links the portal and systemic venous systems. Colour flow and/or power Doppler are usually necessary to confirm their presence on ultrasound.

Splenosystemic shunts are typically found in older female cats and present as a long vessel containing hepatofugal flow, running between the splenic vein and a systemic vein – usually either the left renal vein or the CVC.

Arterioportal fistulae are extremely rare in the cat but should be suspected if a large tortuous vessel is identified within the liver (the main differential being a congenital intrahepatic shunt). Typical features on ultrasound include pulsatile hepatofugal flow of high velocity within the portal vein, ascites and multiple acquired shunts.

Portal vein thrombosis has been reported in the cat. The ultrasound appearance depends on the age of the thrombus, with chronic thrombi typically having an echogenic appearance.

Footnotes

Conflict of interest

The author declares no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.

Funding

The author received no financial support for the research, authorship and/or publication of this article.

References

Kremkau

. Doppler principles. In: Kremkau

. (ed). Sonography principles and instruments 9th ed. St Louis, MO: Elsevier, 2016, pp 131–182.

Nyland

Mattoon

. Fundamentals of diagnostic ultrasound. In: Nyland

Mattoon

(eds). Small animal diagnostic ultrasound. 3rd ed. St Louis, MO: Elsevier, 2015, pp 1–49.

d’Anjou

Penninck

. Practical physical concepts and artifacts. In: d’Anjou

Penninck

(eds). Atlas of small animal ultrasonography. 2nd ed. Iowa: John Wiley & Sons, 2015, pp 1–18.

Martin

. Congenital portosystemic shunts in the dog and cat. Vet Clin North Am Small Anim Pract 1993; 23: 609–623.

Weisse

Berent

. Hepatic vascular anomalies. In: Ettinger

Feldman

Cote

(eds). Textbook of veterinary internal medicine: diseases of the dog and cat. 8th ed. St Louis, MO: Elsevier, 2017, pp 1639–1658.

Lamb

Forster-van Hijfte

White

et al . Ultrasonographic diagnosis of congenital portosystemic shunts in 14 cats. J Small Anim Pract 1996; 35: 205–209.

Lamb

. Ultrasonography of portosystemic shunts in dogs and cats. Vet Clin North AmSmall Anim Pract 1998; 28: 725–753.

Lamb

. Ultrasonographic diagnosis of congenital portosystemic shunts in dogs: results of a prospective study. Vet Radiol Ultrasound 1996; 37: 281–288.

d’Anjou

Penninck

Cornejo

et al . Ultrasonographic diagnosis of portosystemic shunting in dogs and cats. Vet Radiol Ultrasound 2004; 45: 424–437.

10.

d’Anjou

. The sonographic search for portosystemic shunts. Clin Tech Small Anim Pract 2007; 22: 104–114.

11.

Szatmari

Rothuizen

van den Ingh

et al . Ultrasonographic findings in dogs with hyperammonemia: 90 cases (2000-2002). J Am Vet Med Assoc 2004; 224: 717–727.

12.

Tivers

Lipscomb

. Congenital portosys-temic shunts in cats: investigation, diagnosis and stabilisation. J Feline Med Surg 2011; 13: 173–184.

13.

Tivers

Lipscomb

. Congenital porto-systemic shunts in cats: surgical management and prognosis. J Feline Med Surg 2011; 13: 185–194.

14.

Rothuizen

van den Ingh

Voorhout

et al . Congenital portosystemic shunts in sixteen dogs and three cats. J Small Anim Pract 1982; 23: 67–81.

15.

Tillson

Winkler

. Diagnosis and treatment of portosystemic shunts in the cat. Vet Clin North Am Small Anim Pract 2002; 32: 881–899.

16.

Hunt

. Effect of breed on anatomy of portosystemic shunts resulting from congenital diseases in dogs and cats: a review of 242 cases. Aust Vet J 2004; 82: 749–749.

17.

Blaxter

Holt

Pearson

et al . Congenital portosystemic shunts in the cat: a report of nine cases. J Small Anim Pract 1988;29: 631–645.

18.

White

Forster-van Hijfte

Petrie

et al . Surgical treatment of intrahepatic portosystemic shunts in six cats. Vet Rec 1996; 139: 314–337.

19.

Santilli

Gerboni

Olivieri

et al . Ultrasonographic diagnosis of portosystemic communications in dogs and cats: retrospective study of 51 cases [article in Italian]. Veterinaria 2003; 17: 13–23.

20.

Berger

Whiting

Breznock

et al . Congenital feline portosystemic shunts. J Am Vet Med Assoc 1986; 188: 517–521.

21.

Santilli

Gerboni

. Diagnostic imaging of congenital porto-systemic shunts in dogs and cats: a review. Vet J 2003; 166: 7–18.

22.

White

Shales

Parry

. New perspectives on the development of extrahepatic por-tosystemic shunts. J Small Anim Pract 2017; 58: 669–677.

23.

White

Parry

. Morphology of congenital portosystemic shunts involving the left colic vein in dogs and cats. J Small Anim Pract 2016; 57: 247–254.

24.

White

Parry

. Morphology of congenital portosystemic shunts emanating from the left gastric vein in dogs and cats. J Small Anim Pract 2013; 54: 459–467.

25.

Payne

Martin

Constantinescu

. The anatomy and embryology of portosys-temic shunts in dogs and cats. Semin Vet Med Surg (Small Anim) 1990; 5: 76–82.

26.

White

Parry

. Morphology of splenocaval congenital portosystemic shunts in dogs and cats. J Small Anim Pract 2016; 57: 28–32.

27.

Lamb

White

. Morphology of congenital intrahepatic portacaval shunts in dogs and cats. Vet Rec 1998; 142: 55–60.

28.

Nyland

Larson

Mattoon

. Liver. In: Mattoon

Nyland

(eds). Small animal diagnostic ultrasound. 3rd ed. St Louis, MO: Elsevier Saunders, 2015, pp 332–399.

29.

Deppe

Center

Simpson

et al . Glomerular filtration rate and renal volume in dogs with congenital portosystemic vascular anomalies before and after surgical ligation. J Vet Intern Med 1999; 13: 465–471.

30.

Walter

Feeney

Johnston

et al . Feline renal ultrasonography: quantitative analyses of imaged anatomy. Am J Vet Res 1987; 48: 596–599.

31.

Debruyn

Paepe

Daminet

et al . Renal dimensions at ultrasonography in healthy Ragdoll cats with normal kidney morphology: correlation with age, gender and bodyweight. J Feline Med Surg 2013; 15: 1046–1051.

32.

Nyland

Widmer

Mattoon

. Urinary tract. In: Mattoon

Nyland

(ed). Small animal diagnostic ultrasound. 3rd ed. St Louis, MO: Elsevier Saunders, 2015, pp 557–607.

33.

Berent

Tobias

. Portosystemic vascular anomalies. Vet Clin North Am Small Anim Pract 2009; 39: 513–541.

34.

Dear

Shiraki

Ruby

et al . Feline urate urolithiasis: a retrospective study of 159 cases. J Feline Med Surg 2011; 13: 725–732.

35.

Morandi

Sura

Sharp

et al . Characterization of multiple acquired por-tosystemic shunts using transplenic portal scintigraphy. Vet Radiol Ultrasound 2010; 51: 466–471.

36.

Burton

White

. Portovenogram findings in cases of elevated bile acid concentrations following correction of portosystemic shunts. J Small Anim Pract 2001; 42: 536–540.

37.

McConnell

Sparkes

Ladlow

et al . Ultrasonographic diagnosis of unusual portal vascular abnormalities in two cats. J Small Anim Pract 2006; 46: 338–343.

38.

Bertolini

. Acquired portal collateral circulation in the dog and cat. Vet Radiol Ultrasound 2010; 51: 25–33.

39.

Langdon

Cohn

Kreeger

et al . Acquired portosystemic shunting in two cats. J Am Anim Hosp Assoc 2002; 38: 21–27.

40.

Barfield

Gibson

Lipscomb

. Multiple acquired portosystemic shunts in a cat secondary to chronic diaphragmatic rupture. JFMS Open Rep 2015; 1. DOI: 10.1177/2055116915585020.

41.

Zandvliet

Szatmari

van den Ingh

et al . Acquired portosystemic shunting in 2 cats secondary to congenital hepatic fibrosis. J Vet Intern Med 2005; 19: 765–767.

42.

Uemura

Haruyama

Nakata

et al . Hybrid technique coil embolisation for intra-hepatic arterioportal fistula in a cat: case report. JFMS Open Rep 2016; 2. DOI: 10.1177/2055116916642256.

43.

Legendre

Krahwinkel

Carrig

et al . Ascites associated with intrahepatic arterio-venous fistula in a cat. J Am Vet Med Assoc 1976; 168: 589–591.

44.

Vogt

Krahwinkel

Jr Bright

et al . Gradual occlusion of extrahepatic portosys-temic shunts in dogs and cats using the ameroid constrictor. Vet Surg 1996; 25: 495–502.

45.

VanGundy

Boothe

Wolf

. Results of surgical management of feline portosystemic shunts. J Am Anim Hosp Assoc 1990; 26: 55–62.

46.

Bosje

van den Ingh

van der Linde-Sipman

. Polycystic kidney and liver disease in cats. Vet Q 1998; 20: 136–139.

47.

Palerme

Brown

Marks

et al . Splenosystemic shunts in cats: a retrospective of 33 cases (2004-2011). J Vet Intern Med 2013; 27: 1347–1353.

48.

Specchi

Panopoulos

Adrian

et al . A ‘spaghetti sign’ in feline abdominal radiographs predicts spleno-systemic collateral circulation. Vet Radiol Ultrasound 2018; 59: 13–17.

49.

Matsuura

Takahashi

Yanagi

et al . Surgical strategy according to the anatomical types of congenital portosystemic shunts in children. J Pediatr Surg 2016; 51: 2099–2104.

50.

Henseler

Pozniak

Lee

Jr et al . Three-dimensional CT angiography of spontaneous portosystemic shunts. Radiographics 2001; 21: 691–704.

51.

Achiwa

Hirota

Kako

et al . Radiological anatomy of spontaneous splenorenal shunts in patients with chronic liver disease. Jpn J Radiol 2017; 35: 206–214.

52.

Kim

Giglio

Reese

et al . Comparison of computed tomographic angiography and ultrasonography for the detection and characterization of portosystemic shunts in dogs. Vet Radiol Ultrasound 2013; 54: 569–574.

53.

Bailey

Willard

McLoughlin

et al . Ultrasonographic findings associated with congenital hepatic arteriovenous fistula in three dogs. J Am Vet Med Assoc 1988; 192: 1099–1101.

54.

Holloway

Groot

van der Schaaf

. Congenital absence of the portal vein in a cat. JFMS Open Rep 2018; 4. DOI: 10.1177/2055116917749079.

55.

Kumar

Hanlin

Glurich

et al . Virchow’s contribution to the understanding of thrombosis and cellular biology. Clin Med Res 2010; 8: 168–172.

56.

Rogers

O’Toole

Keating

et al . Portal vein thrombosis in cats: 6 cases (2001-2006). J Vet Intern Med 2008; 22: 282–287.

57.

Zwiebel

. Sonographic diagnosis of hepatic vascular disorders. Semin Ultrasound CT MR 1995; 16: 34–48.

Feline abdominal ultrasonography: what’s normal? what’s abnormal? Hepatic vascular anomalies

Abstract

Practical relevance:

Clinical challenges:

Equipment:

Aim:

Evidence base:

Keywords

Portosystemic shunts

Congenital portosystemic shunts

Congenital extrahepatic shunts

Congenital intrahepatic shunts

Acquired portosystemic shunts

Splenosystemic shunts

Portal vascular abnormalities

Arterioportal fistulae

Portal vein aplasia

Portal vein thrombosis

Key Points

Footnotes

Conflict of interest

Funding

References