Wiener Tierärztliche Monatsschrift – Veterinary Medicine Austria 101 (2014)

From the Department of Medicine and Clinical Biology of Small Animals1, the Department of Medical Imaging of Domestic Animals and Small Animal Orthopaedics2, and the Department of Nutrition, Genetics and Ethology3, Faculty of Veterinary Medicine, Ghent University, Merelbeke, Belgium, as well as Medvet Veterinary Pathology Services4, Antwerp, Belgium Congenital extrahepatic portoazygos in combination with hepatic microvascular dysplasia in a

N. DEVRIENDT1, D. PAEPE1, E. VANDERMEULEN2, G. QUIST-RYBACHUK3, H.E.V. DE COCK4, J.H. SAUNDERS2, T. BOSMANS1, G. PAES1 and H. DE ROOSTER1*

received April 27, 2013 accepted November 12, 2013

Keywors: Dogs, portoazygos shunt, hepatic micro- Schlüsselwörter: Hunde, Portoazygos-Shunt, hepati- vascular dysplasia, imaging, histology. sche mikrovaskuläre Dysplasie, Bildgebung, Histologie. Summary Zusammenfassung

A ve-year-old, female castrated Yorkshire Terrier Kongenitaler portosystemischer Shunt in was presented with complaints of decreased activity Kombination mit hepatischer mikrovaskulärer and appetite, fever, a painful abdomen and lower Dysplasie bei einem Yorkshire Terrier urinary tract symptoms. Based on blood and urinalysis there was a strong suspicion of Eine kastrierte fünfjährige Yorkshire Terrier- disease and a urinary tract infection. Abdominal Hündin wurde mit Symptomen verminderter Akti- ultrasound revealed a portoazygos shunt, bilateral vität, verminderten Appetits, Fieber und Abdo- nephrolithiasis and pyelectasia raising the suspicion minalschmerz sowie Symptomen des unteren of pyelonephritis. However, pyelonephritis could not Harntraktes vorgestellt. Die Laboruntersuchung be con rmed because urine culture – while the dog von Blut und Harn deutete auf eine Leber- received – was negative. A shunt fraction erkrankung und eine Infektion der Harnwege of 99% was con rmed on scintigraphy. After medical hin. Die Ultraschalluntersuchung des Abdomens stabilization, the shunt was surgically attenuated zeigte einen Portoazygos-Shunt, eine bilaterale using a cellophane band. Postoperatively, conserva- Nephrolithiasis und Pyelektasie, was den Verdacht tive treatment was continued and the dog became auf eine Pyelonephritis ergab. Jedoch konnte clinically asymptomatic, although serum pre- and eine Pyelonephritis mittels Harnkultur nicht postprandial bile acid concentrations remained bestätigt werden, da diese während der Antibio- elevated. Six months after the surgical intervention, tikabehandlung durchgeführt wurde. Die Szinti- a persistent or acquired shunt was excluded by graphie bestätigte eine Shunt-Fraktion von 99 %. subsequent scintigraphy (shunt fraction 0.88%). Nach medikamentöser Stabilisierung wurde der Surgical liver biopsies were taken and routine histo- Shunt chirurgisch mit einem Zellophanband pathology revealed hepatic microvascular dysplasia. reduziert. Die medikamentöse Therapie wurde postoperativ fortgesetzt und die Hündin zeigte keine erkennbaren Symptome mehr. Jedoch blieben die präprandialen und postprandialen Gallensäure-Konzentrationen dauerhaft erhöht. Sechs Monate nach der Operation konnte durch eine weitere Szintigraphie ein persistierender oder erworbener Shunt ausgeschlossen werden (Shunt-Fraktion 0.88 %). Die pathohistologi- sche Untersuchung der durchgeführten Leber- Abbreviations: PPS = portosystemic shunt; EHPSS = ex- trahepatic portosystemic shunt; HMD = hepatic microvas- biopsie ergab das Vorliegen einer hepatischen cular dysplasia; IH = immunohistochemistry mikrovaskulären Dysplasie.

58 Wiener Tierärztliche Monatsschrift – Veterinary Medicine Austria 101 (2014)

Introduction isothenuria (Tab. 2). No crystals were detected during microscopic evaluation of the urine sample and A portosystemic shunt (PSS) is an abnormal vascu- bacteriological urine culture was negative. lar communication between the portal venous and On abdominal ultrasound, the liver was considered systemic circulation that causes the majority of blood normal in size and shape and had a homogeneous to  ow from the intestinal tract directly to the right parenchyma. An aberrant blood vessel was visible, heart, bypassing the liver. Portosystemic shunts are originating from the portal vein and running dorsally the most common congenital diseases of the hepato- towards a blood vessel near the aorta. Examination of billiary system of dogs and can occur intrahepatically the kidneys revealed bilateral nephrolithiasis and mild or extrahepatically (BROOME et al., 2004). After por- pyelectasia at the level of the nephroliths (Tab. 3). tocaval shunts, portoazygos shunts are the second The dog was diagnosed with a congenital EHPSS most common type of extrahepatic portosystemic and was suspected of having a pyelonephritis, based shunts (EHPSS) in dogs (KUMMELING et al., 2004). on the presence of pyelectasis, active sediment, Hepatic microvascular dysplasia (HMD) is a con- decreased kidney function and fever. genital disease in which microscopic intrahepatic The dog was hospitalized and infusion therapy portovenous shunts are present (SCHERMERHORN initiated at 100 ml/kg/24 hours (NaCl 0.9%). et al., 1996; ALLEN et al., 1999). Microscopic shunting therapy was instituted, combining / may occur in isolation or may coexist with a macro- spiramycine to decrease the number of urease- scopic PSS and has a similar clinicopathological pre- producing bacteria in the intestines (Stomorgyl®, me- sentation to a PSS (SCHERMERHORN et al., 1996; tronidazole 12.5 mg/kg and spiramycine 25 mg/kg ALLEN et al., 1999; LANDON et al., 2008). The pre- BID p.o.) and amoxicillin/clavulanic acid to treat the valence of HMD is suggested to be twice to 30 times suspected urinary tract infection (Augmentin P500® higher than the prevalence of PSS (SCHERMERHORN 20 mg/kg TID i.v.) Additionally, lactulose (Lactulose et al., 1996; CENTER, 2009). EG® 0.5 mL/kg TID p.o.), ranitidine (Zantac® 0.5 mg/kg A Yorkshire Terrier with a combination of an EHPSS BID i.v.), metoclopramide (Primperan® 0.3 mg/kg TID and HMD will be described. The simultaneous i.v.) and methadone (Mephenon® 0.2 mg/kg q4 hours occurrence of both congenital diseases has been pre- i.v.) were administered. A highly digestible liver diet viously reported in veterinary literature (ALLEN et al., (Hill’s Prescription Diet Canine l/d®) was fed, with the 1999; LANDON et al., 2008). However, special daily amount divided into ve meals. On day three, the attention will be given to the challenges of diagnosing dog developed stupor. An enema was performed with HMD in the presence of a patent macroscopic PSS. a solution of 20 ml/kg lactulose and 45 ml/kg luke- warm water, after which the overall clinical state of the Case report dog improved. A transsplenic scintigraphic scan was performed at day ve, under total intravenous anaes- A ve-year-old, female castrated Yorkshire Terrier thesia using propofol (Propovet® up to 6 mg/kg i.v. was presented with a history of chronic recurrent to effect). Sodium 99mTc pertechnetate (±0.2 ml; bacterial cystitis. During the ve days prior to presen- 118.4 MBq) was injected into the splenic parenchyma tation, the dog was lethargic, partially anorectic and under ultrasound guidance and a dynamic frame developed pollakisuria, stranguria and haematuria. mode acquisition was used (Toshiba GCA single-head The referring veterinarian detected an elevated rectal gamma-camera with low-energy, high-resolution temperature (40 °C), a heart murmur and a painful ab- (LEHR) collimator; acquisition protocol: four frames domen. Blood samples were taken and revealed mild per s total 240 frames or 1 min acquisition time). A leucocytosis, mild azotaemia, severe elevated post- shunt fraction of 99% was present (Fig. 1). prandial bile acids and moderate hypoalbuminaemia The dog was discharged at day seven with (Tab. 1). The dog was injected on two consecutive amoxicillin/clavulanic acid (Clavubactin® 12.5 mg/kg days with anticholinergics and antibiotics (preparation BID p.o.), to be continued for another two weeks, to and dosage unknown), without clinical improvement. treat the suspected urinary tract infection. The PSS On admission (day zero) the dog was still partially therapy included the liver diet, lactulose and anorectic and lower urinary tract signs persisted. On metronidazole/spiramycine. physical examination, the dog was calm but alert, had A week after nishing the antibiotics (day 28), a body condition score of 5/9 (Purina BCS), a mild previous abnormalities detected on renal ultra- systolic heart murmur and was normothermic sonography, blood and urinalysis had improved (38.4 °C). Abdominal palpation was very painful but (Tab. 1–3). The owners did not report any clinical symp- the origin of pain was dif cult to assess. Blood ana- toms and physical examination was unremarkable. lysis was repeated and revealed similar abnormalities, At day 47, the shunting vessel was surgically including severe elevated pre- and postprandial bile attenuated. Premedication consisted of methadone acids (Tab. 1). Urinalysis revealed moderate (0.2 mg/kg i.v.) and induction was performed using proteinuria, severe pyuria, severe haematuria and propofol (up to 6 mg/kg i.v. to effect). Anaesthesia was

59 Wiener Tierärztliche Monatsschrift – Veterinary Medicine Austria 101 (2014)

Tab. 1: Haematology and serum biochemistry of a Yorkshire Terrier with a combination of extrahepatic portoazygos shunt and hepatic microvascular displasia from the rst presentation at the referring veterinarian until six months postoperatively

D-2 D0 D28 D83 D118 D167 D231 D285

Packed cell volume (%) 46 37.2 40.5 39.3 35 41.0 46.3 43.7 37-55a 37.0-55.0 b 43.0-59.0c 43.0-59.0c 43.0-59.0c 43.0-59.0c 43.0-59.0c 43.0-59.0c

Leukocytes (x109/l) 16.4 25.32 19.98 36.22 11.8 – – – 6.0–12.0a 5.50-16.90b 6.00-16.00c 6.00-16.00c 6.00-16.00c

Urea (mmol/l) 28.2 24.6 4.16 7.33 -5.16 5.49 7.16 – (35–106)a (2.5-9.6)b (1.16-8.49) c (1.16-8.49) c (1.16-8.49) c (1.16-8.49) c (1.16-8.49) c

Creatinine (µmol/l) 124 150 65.4 64.5 64.5 68.1c 70.7 – (35–106)a (44-159)b (60+LG(3.5 kg))c (60+LG(3.5 kg))c (60+LG(3.5 kg))c (60+LG(3.5 kg))c (60+LG(3.5 kg))c

Alanine transaminase (U/l) 82 22 48 – – – – – (<88)a (10-100)b (<53)c

Alkaline phosphatase (U/l) 463 52 17 – – – – – (>20)a (23-212)b (<86)c

Bile acids (µmol/l) pre- prandial - 114 – 125 65 53 231 –

post- 242 232 88 107 69 88 66 – prandial (<20)a (<12)b (<12)c (<12)c (<12)c (<12)c (<12)c

Total protein (g/l) 56 58 60 – – – – – (54–5)a (55-78)c (52-82)b

Albumin (g/l) 21 29.4 30 41.9 – – – – (25–44)a (31.0-44.0)c (23-40)b (31.0-44.0)c

D-2: 2 days prior to presentation – D231: 231 days after presentation; a: Analysis performed by the referring veterinarian; b: Analysis performed in the in-house laboratory of Ghent University; c: Analysis performed at an external laboratory

Tab. 2: Urinalysis of a Yorkshire Terrier with a combination of extrahepatic portoazygos shunt and hepatic microvascular displasia (urine collected via ultrasound-guided transabdominal cystocenthesis)

Day 0 Day 28 Day 118 Day 167 Day 231 Reference values

pH 6.5 6.0 5.5 5.5 6.0 4.5 -7.0

Leukocytes (/µl) 1,739a 15 858 43 11 <25

Erythrocytes (/µl) 3,129 50 4,513 800 20 <25

Protein/creatinine ratio 2.5 0.91 0.87 0.41 0.24 <0.50

Speci c gravity 1.013 1.018 1.021 1.021 1.023

Crystals negative negative negative negative negative

Culture negative negative negative negative negative a mainly neutrophils, few monocytes and macrophages

60 Wiener Tierärztliche Monatsschrift – Veterinary Medicine Austria 101 (2014)

Tab. 3: Urinary tract ultrasonography of a Yorkshire Terrier with a combination of extrahepatic portoazygos shunt and hepatic microvas- cular displasia

Day 0 Day 28 Day 118 Day 167 Day 231 Day 385

Kidneys Normal Normal Normal Normal Normal Normal

Renal pelvices

Left Mildly dilated Normal Normal Normal Mildly dilated Normal

Right Mildly dilated Normal Mildly dilated Mildly dilated Mildly dilated Mildly dilated

Nephroliths

0.8 cm, 0.5 cm, 0.54 cm, Left 1.4 cm Idem 1.1 cm under 0.8 cm under 0.5 cm 0.34 cm

0.33 cm, Right 1.3 cm Idem 0.65 cm None 0.2cm 0.12 cm

Ureter

Left Normal Normal Normal Normal Normal Normal

Right Mildly dilated Normal Normal Mildly dilated Mildly dilated Normal

Ureterolith

Left None None None None None None

Right None None None 0.2 cm 0.3 cm None

Bladder content Sediment Anechoic Sediment Sediment Sediment Sediment maintained with iso urane (Iso o®) vaporized in oxy- lation of the shunt, the heart rate doubled and the in- gen using a rebreathing system. Cefazoline (Cefazoli- testines coloured blue, but these conditions norma- ne Mylan® 20 mg/kg i.v.) was administered and through- lized when manipulation ceased, indicating no out the surgery the dog received 10 ml/kg/h i.v. NaCl persistent signs of . Postoperative 0.9% solution and a constant rate infusion of remifen- medical treatment included intravenous  uid therapy tanil (Ultiva® 15–20 µg/kg/hour i.v.), to achieve analge- (NaCl 0.9%, 100 ml/kg/24 hours), cefazoline (20 mg/ sia. A ventral midline celiotomy was performed. The kg TID i.v.), ranitidine (2 mg/kg BID i.v.) and methadone abdominal fat was yellow-tinged and the liver lobes (0.3 mg/kg q4 hours i.v.). Administration of lactulose, were subjectively small and extremely fragile. Liver metronidazole/spiramycine therapy and the liver diet lobes had a mottled aspect, which was yellow to orange were reinstated. Three days after surgery, the dog was centrally and more red in the periphery. Both kidneys discharged and medical management of the PSS was were macroscopically normal and both ureters were continued at home. subjectively mildly dilated over their entire lengths, wi- Control visits were performed regularly, including thout any evidence of uroliths. The shunting vessel urinary tract ultrasonography and blood and urina- was identi ed: it arose from the splenic vein and dis- lysis (Tab. 1–3). The dog remained asymptomatic but appeared dorsally towards the stomach and into the because of persistently high serum bile acid concen- diaphragm, indicating a portoazygos shunt. It had a trations, three months after surgery (day 170) the scin- diameter of 7 mm and was bluntly dissected at the tigraphic scan was repeated. Sodium 99mTc pertech- level of the diaphragm. A three-layer 4 mm cellophane netate (±0.2 ml; 103.6 MBq) was injected into the band was placed around the shunting vessel and se- splenic parenchyma under ultrasound guidance and cured to itself with a vascular clip and an additional a dynamic frame mode acquisition was performed, suture around a 4 mm measuring rod. During manipu- using the same parameters and gamma camera as for

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As a persistent or acquired PSS was excluded by means of ultra- sound and scintigraphy, the diag- nosis of HMD was made. Adminis- tration of metronidazole/spira- mycine was ceased, whereas liver diet and lactulose were continued and a food supplement containing S-adenosylmethionine (Zentonil advanced®) was added to stimu- late hepatic regeneration. Eleven months after surgical attenuation of the EHPSS and four months after diagnosis of HMD (day 385), the dog was still asymptomatic, although bile acid concentrations were still elevated and nephroliths were still present (Tab. 1 and 3).

Source of supply: NaCl 0.9%, B. Braun Melsungen Fig. 1: Pre-operative transsplenic scintigraphic scan of a Yorkshire Terrier with a combination AG, Germany; Stomorgyl®, metroni- of extrahepatic portoazygos shunt and hepatic microvascular displasia: the activity is by- dazole spiramycine Merial, France; passing the liver and arrives rst in the heart, indicating the presence of a portosystemic ® shunt. The track of the tracer is indicative of a portoazygos shunt. The top-left image is a Augmentin P500 GlaxoSmithKLine composite image of all 240 frames, which is used for region of interest (ROI) placement (ROI plc (GSK), United Kingdom; Lactu- 1 = cardiac area, ROI 2 = hepatic area, ROI 3 = ROI in the dorsal cervical soft tissue, used lose EG® Eurogenerics NV, Belgium; for background correction). The graph at the bottom-left is a time - activity curve (time on the ® X axis, portoazygos or ‚counts‘ on the Y axis) and demonstrates the arrival of the injected Zantac GlaxoSmithKLine plc activity in the cardiac region, thereby bypassing the hepatic region. The gure on the right is (GSK), United Kingdom; Primperan® composed of selected frames (2 frames per image, added to improve the ‚readability‘ of the Sano -Aventis, France; Mephenon® scan). The pathway of the injected activity can be followed on these separate 2-frame images. Denolin NV, Belgium; Hill’s Pre- scription Diet Canine l/d®, Hill’s Pet the rst scintigraphic examination. The postoperative Nutrition, Inc., United States; Propovet®, Abbott Labora- shunt fraction was 0.88% (Fig. 2). tories Limited, United States; Clavubactin® Le Vet Pharma, Six-and-a-half months after the initial surgery (day the Netherlands; Iso o®, Abbott Laboratories Limited, 245), an exploratory cranial celiotomy was performed United States; Cefazoline Mylan® Mylan Inc., United to take liver biopsies because of persistently high bile States; Ultiva® GlaxoSmithKLine plc (GSK), United King- acids. Various possibilities to take liver biopsies (ultra- dom; Zentonil advanced®, Vétoquinol SA, France sound-guided, exploratory celiotomy) were discussed with the owners. They elected a surgical procedure to Discussion have the opportunity to check the complete liver and vasculature and to be able to take larger biopsies. The present case report describes a Yorkshire Several abdominal adhesions were present but the Terrier in which EHPSS and HMD coexisted. It has cellophane band could be identi ed in the left cranial been suggested that approximately 10% of dogs with abdomen near the diaphragm. Subjectively, the liver a congenital PSS have additional HMD, irrespective of had increased in size since the previous surgery and the breed (VAN STRATEN et al., 2005). Small pure the parenchyma was obviously less fragile. It had a breeds, such as Yorkshire Terriers, are prone to have pale-coloured surface, with a yellowish periphery. The both EHPSS and HMD (CHRISTIANSEN et al., 2000). borders of the right liver lobes were sharp but the left The presence of HMD is often suspected after lobes were rather rounded. Multiple liver biopsies excluding a macroscopic PSS (PHILLIPS et al., 1996; of several liver lobes were taken using the guillotine CHRISTIANSEN et al., 2000). Nevertheless, the method. suspicion of HMD in a patient with a concomitant Histopathology of all liver biopsies showed poorly patent PSS poses a diagnostic challenge as both differentiated periportal veins and mild to moderate diseases have similar clinicopathologic characteris- arteriolar proliferation. Some of the centrolobular tics (PHILLIPS et al., 1996; ALLEN et al., 1999). One veins could easily be identi ed, whereas others were study (ALLEN et al., 1999) claimed to compare small and collapsed. A diffuse vacuolar degeneration clinicopathologic features between dogs with HMD of the hepatocytes was visible, with a pronounced and dogs with the combination of HMD and a PSS. presence of lipogranulomas (Fig. 3). However, the actual presence of HMD in all dogs with

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a patent PSS in that particular study can be questioned as no extra group with isolated PSSs was included. Dogs with PSS, dogs with HMD and dogs with a combination of both disorders can suffer from neurological, gastroin- testinal and urinary symptoms (ALLEN et al., 1999; CHRISTIAN- SEN et al., 2000; WATSON, 1997). Up to 50% of the dogs with PSS have uroliths (WATSON, 1997), which are typically ammonium acid urate stones (GRAUER, 2009). Urinary crystals are equally detected in dogs with PSS and in patients with HMD (ALLEN et al., 1999) but urolithiasis seems to be less common in the latter (CHRISTIANSEN et al., 2000; D‘ANJOU, 2007). Although ammo- nium acid urate crystals are a Fig. 2: Transsplenic scintigraphic scan six months after surgical attenuation of the shunt: common nding in dogs with a The activity arrives rst in the liver before it travels towards the heart, indicating the ab- sence of a portosystemic shunt. The top-left image is a composite image of all 240 frames, PSS and concurrent urolithiasis, which is used for ROI placement (ROI 1 = cardiac area, ROI 2 = hepatic area, ROI 3 = no crystals were found in the urine ROI in the dorsal cervical soft tissue, used for background correction). The graph at the sediment of this dog despite bottom-left is a time - activity curve (time on the X axis, activity or ‚counts‘ on the Y axis) and demonstrates the arrival of the injected activity in the hepatic area (ROI 2) before en- repeated urinalysis. In the presen- tering the cardiac region (ROI 1). The gure on the right is composed of selected frames ted case, it is very likely that the (2 frames per image, added to improve the ‚readability‘ of the scan). The pathway of the uroliths were a consequence of injected activity can be followed on these separate 2-frame images. the congenital hepatoportal abnormalities. However, their composition was never nephroliths are a predisposing factor for an ascending examined: because of the localization, stone removal infection from the bladder and the dog had a history was thought to be too invasive. The presence of HMD of recurrent bacterial cystitis. The nephroliths could can explain why the nephroliths did not resolve after have contributed to the presence of pyelectasis, attenuation of the PSS. The presence of pyelectasis, although this would not have explained the fever. active sediment, decreased kidney function and fever Recurrence of a bacterial cystitis was also considered raised the suspicion of pyelonephritis. In addition, less likely, as it would not explain the fever or the general clinical symptoms. Bacterial culture of urine taken by cystocenthesis was negative, so pyelone- phritis could not be con rmed. However, the dog had already received antibiotics for two days prior to culture and was afebrile at the time of urine sampling, making false negative urine culture likely. Although a urinary tract infection may facilitate the formation of crystals, in this case the suspected urinary tract infection was more likely to be secondary to the uroliths that caused mucosal irritation and urine stasis (GRAUER, 2009). Abnormal values for pre- and postprandial serum bile acid concentrations are encountered in dogs with PSS as well as in dogs with HMD but the increase is generally less prominent in patients with HMD alone (PHILLIPS et al., 1996; ALLEN et al., 1999). Similar ndings were obtained in this case, as serum bile acid Fig. 3: Histopathology of the liver six-and-a-half months after surgical attenuation of a single extrahepatic portosystemic shunt: concentrations were severely elevated at the rst diffuse vacuolar degeneration of the hepatocytes, mild arteriolar presentation but only moderately elevated after the proliferation (A), poorly differentiated periportal veins (V), some successful surgical attenuation of the EHPSS. Differ- bile ducts (B) and the pronounced presence of lipogranulomas (L) (bar = 20 µm). ential diagnosis for the persistent elevated bile acid

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concentration after surgical attenuation of a PSS are a PSS cannot be differentiated solely on the basis of an incomplete closure of the PSS, recanalization, the histopathology (PHILLIPS et al., 1996; BAADE et al., presence of HMD, a second anomalous vessel or the 2006; LANDON et al., 2008). As the liver biopsies in development of multiple acquired shunts. the present case were taken after scintigraphically Ultrasonography is still regarded as the best con rmed closure of the EHPSS, the histological non-invasive method for assessing the internal liver abnormalities con rmed the presence of HMD. structure, including portal and hepatic vascular Unlike dogs with PSS, in which surgical intervention supply, as it is highly available and relatively cheap to close the shunting vessel gradually is preferable, in (D’ANJOU, 2007). Ultrasonographic sensitivity for dogs with HMD medical treatment is the only option. detecting macroscopic PSS using Doppler is 95% The response to treatment and the prognosis of dogs and its speci city can reach 98% (LAMB, 1996). with HMD are variable and depend on the number of Unless a macroscopic shunting vessel can be liver lobes affected. The majority of dogs have a visualized, ultrasonographic differentiation between relatively good prognosis and can have a normal life dogs with PSS and dogs with HMD alone is very expectancy, even without treatment (CENTER, 2009). subtle (D‘ANJOU, 2007). A higher ratio between the If young dogs with HMD develop symptoms and diameter in the portal vein and aorta, a higher mean medical treatment is delayed until a later age, the portal  ow velocity and the absence of caudal vena prognosis for improvement is guarded to cava enlargement may suggest the presence of HMD poor and recurrence of symptoms is very likely (D’ANJOU, 2007). Scintigraphy is a functional imaging (CHRISTIANSEN et al., 2000). Patients with HMD have technique based on injection of radionuclides to morphological hypoplasia of the portal vessels, demonstrate the presence of a macroscopic PSS whereas functional hypoplasia occurs in patients with (DANIEL and BERRY, 2006). The shunt fraction a PSS. In the latter, the portal vessels normalize after provides an estimated percentage of portal blood that being challenged with portal blood  ow following bypasses the liver. In dogs with HMD, the radionuclide successful attenuation of the PSS (SZATMARI et al., will be distributed throughout the liver parenchyma 2004a, 2004b). The true coexistence of HMD and a but bypass the hepatic sinusoids, giving the PSS will negatively in uence the outcome after impression of a normal perfusion of the liver surgical correction of the PSS and thus this pre- (MORANDI et al., 2005; DANIEL and BERRY, 2006). operative knowledge is prognostically relevant. In the Magnetic resonance angiography and computed case described, all clinical symptoms disappeared tomography angiography are imaging techniques to after starting medical treatment and the patient scan vasculature anatomy. However, microvascular remained asymptomatic even after cessation of the anomalies in dogs with HMD are considered too small metronidazole/spiramycine. to be adequately visualized by these techniques In conclusion, HMD is a common congenital (SEGUIN et al., 1999; ZWINGENBERGER et al., 2005). disease in dogs that can coexist with PSS and has a Histopathological ndings in dogs with a macro- similar clinical presentation. In this dog, clinical signs scopic PSS include portal venous hypoplasia, of HMD were not apparent, probably because of arteriolar and ductular proliferation, mild to moderate supportive therapy (liver diet, lactulose, S-Adenosyl- brosis, hepatocellular atrophy and the presence of methionine). The clinical suspicion was based on lipogranulomas (BAADE et al., 2006; LANDON et al., persistently elevated bile acids after successful shunt 2008). Dogs with HMD have similar abnormalities and attenuation. Based on signalment, clinical symptoms, can have additional central venous muscular hyper- blood and urinalysis and medical imaging, it is impos- trophy and an abnormal orientation of central veins sible to diagnose HMD as long as a patent with respect to the portal triads (SCHERMERHORN macroscopic shunting vessel is present. Although the et al., 1996; LANDON et al., 2008). According to one clinical importance of HMD is not always clear, study, dogs with HMD have portal and periportal veins additional investigations are needed to nd a useful that are signi cantly more dilated than in dogs with a test to diagnose both disorders before planning PSS (PHILLIPS et al., 1996). Nevertheless, HMD and surgical intervention.

References

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