Ultrasonographic findings in dogs with hyperammonemia: 90 cases (2000–2002)

Abstract

Objective—To determine ultrasonographic abnormalities in dogs with hyperammonemia. Design—Retrospective study. Animals—90 client-owned dogs with hyperammonemia. Procedure—Ultrasonography of the abdominal vessels and organs was performed in a systematic way. Dogs in which the ultrasonographic diagnosis was a congenital portosystemic shunt were included only if they underwent laparotomy or necropsy. Dogs in which the abdominal vasculature appeared normal and dogs in which the ultrasonographic diagnosis was acquired portosystemic shunts and portal hypertension were included only if liver biopsy specimens were submitted for histologic examination. Results—Ultrasonography excluded portosystemic shunting in 11 dogs. Acquired portosystemic shunts were found in 17 dogs, of which 3 had arterioportal fistulae and 14 had other hepatic abnormalities. Congenital portosystemic shunts were found in 61 dogs, of which 19 had intrahepatic shunts and 42 had extrahepatic shunts. Intrahepatic shunts originated from the left portal branch in 14 dogs and the right portal branch in 5. Extrahepatic shunts originated from the splenic vein, the right gastric vein, or both and entered the caudal vena cava or the thorax. Ultrasonography revealed splenic-caval shunts in 24 dogs, right gastric-caval shunts in 9 dogs, splenic-azygos shunts in 8 dogs, and a right gastric-azygos shunt in 1 dog. Conclusions and Clinical Relevance—Results suggest that ultrasonography is a reliable diagnostic method to noninvasively characterize the underlying disease in dogs with hyperammonemia. A dilated left testicular or ovarian vein was a reliable indicator of acquired portosystemic shunts. (J Am Vet Med Assoc 2004;224:717–727)

Unusual haemodynamics in two dogs and two cats with portosystemic shunt - implications for distinguishing between congenital and acquired conditions

“…http://www.openveterinaryjournal.com M. Ricciardi Open Veterinary Journal, (2017 On the other hand patients with congenital PSS are traditionally described as having a single porto-caval connection without ascites or portal flow obstruction (Szatmari et al, 2004;Bertolini et al, 2006;Nelson and Nelson, 2011;Fukushima et al, 2014). Furthermore, current classification of canine PSS differentiate repeatable and distinct vascular patterns of CPSS and APSS without any overlapping of anatomical pathway between each category (Ricciardi, 2016).…”

“…These vascular anomalies are divided in two main categories according to their origin: congenital PSS (CPSS) deriving from embryogenetic errors in the development of vitelline and cardinal venous systems (Ferrell et al, 2003), and acquired PSS (APSS) deriving from recanalization of pre-existing, vestigial embryonic vascular connections between portal and caval systems as a consequence of portal hypertension (PH) (Fossum, 2002;Szatmari et al, 2004;Bertolini, 2010a). Ultrasound and computed tomography (CT) are reliable imaging techniques for the non-invasive diagnosis of PSSs and for distinction between acquired and congenital shunts (Szatmari and Rothuizen, 2002;Szatmari et al, 2004;Ricciardi, 2016). Such imaging distinction is essential for differentiating hypertensive patients, which need further investigations in order to diagnose the cause of the underlying PH, from those that need surgical closure of a congenital vascular malformation.…”

Standard planes for ultrasonographic examination of the portal system in dogs

“…Indeed, in our experience, congenital extrahepatic spleniccaval shunts seem to be surrounded by liver when they are scanned via a right intercostal approach. In a study 16 of 90 dogs with hyperammonemia, we found that the present protocol for systematic ultrasonographic evaluation of the portal system was effective in identifying CPSSs and APSSs and ruling out portosystemic shunting in dogs with urea cycle enzyme deficiencies. In our experience, however, high accuracy also required that in addition to use of the scanning protocol, a high-quality ultrasound machine with excellent gray scale resolution was needed.…”

“…However, we believe that in 2 of these studies, some extrahepatic CPSS were not recognized because only a right intercostal approach was used. For example, in a study 16 of 90 dogs with hyperammonemia secondary to CPSSs, APSSs, or urea cycle enzyme deficiency, we found that congenital extrahepatic right gastric-caval shunts cannot be readily identified from a right intercostal approach because visualization of the Figure 2-Ultrasonogram of the abdomen of a healthy male adult Beagle. The dog was in left lateral recumbency, and the transducer was oriented transversely and placed in a more cranial right intercostal space, compared with the orientation in Figure 1 (plane 2).…”

“…Thus, their origins and courses can only rarely be revealed. In our study 16 of dogs with hyperammonemia, however, dilatation of the left testicular or ovarian vein was found to be a highly specific and sensitive indicator of APSSs, and its ultrasonographic visualization was easy.…”