Liver: vascular disorders

Mickey Tivers

doi:10.22233/9781910443361-3e.37b

British Small Animal Veterinary Association , 268 (2020); https://doi.org/10.22233/9781910443361-3e.37b

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Liver: vascular disorders

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Author: Mickey Tivers
From: BSAVA Manual of Canine and Feline Gastroenterology
Item: Chapter 37b, pp 268 - 276
DOI: 10.22233/9781910443361-3e.37b
Copyright: © 2020 British Small Animal Veterinary Association
Publication Date: January 2020

Abstract

This chapter describes the structure and function of the vasculature of the liver, and the pathophysiology, diagnosis and management of vascular disease.

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Figures

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37.23

Photomicrograph of a liver biopsy sample from a dog with a congenital portosystemic shunt, showing an abnormal portal tract with marked arteriole hyperplasia and absent portal veins. The number of aberrant arterioles is dramatically increased. There is also microvesicular vacuolar change affecting the hepatocytes, indicative of hepatocyte degeneration. (Haematoxylin and eosin; original magnification X200.) © 2020 British Small Animal Veterinary Association

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37.23 Photomicrograph of a liver biopsy sample from a dog with a congenital portosystemic shunt, showing an abnormal portal tract with marked arteriole hyperplasia and absent portal veins. The number of aberrant arterioles is dramatically increased. There is also microvesicular vacuolar change affecting the hepatocytes, indicative of hepatocyte degeneration. (Haematoxylin and eosin; original magnification X200.)

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37.24

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37.24 A cat with a congenital extra-hepatic portosystemic shunt (CPSS). Note the copper-coloured irises that are commonly seen in cats with CPSS.

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37.26

An 18-month-old female neutered crossbreed dog with severe hepatic encephalopathy (HE) due to a congenital extra-hepatic portosystemic shunt. The dog is collapsed and obtunded. The dog significantly improved with medical management of HE. © 2020 British Small Animal Veterinary Association

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37.26 An 18-month-old female neutered crossbreed dog with severe hepatic encephalopathy (HE) due to a congenital extra-hepatic portosystemic shunt. The dog is collapsed and obtunded. The dog significantly improved with medical management of HE.

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37.28

Reconstructed dorsal plane computed tomography angiography image of a congenital left divisional intra-hepatic portosystemic shunt (arrowed) in a dog. CVC = caudal vena cava; PV = portal vein. © 2020 British Small Animal Veterinary Association

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37.28 Reconstructed dorsal plane computed tomography angiography image of a congenital left divisional intra-hepatic portosystemic shunt (arrowed) in a dog. CVC = caudal vena cava; PV = portal vein.

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37.29

A series of ventrodorsal intraoperative mesenteric portovenograms from a 19-week-old male entire West Highland White Terrier with an extra-hepatic congenital portosystemic shunt (CPSS). The images are orientated so that cranial is at the top. (a) Intraoperative portovenogram image. Contrast medium has been injected through a jejunal vein under fluoroscopic guidance with digital subtraction. The majority of the contrast medium, and hence blood, flows through the large shunt vessel (arrowed) on the right of the image. The portal vein and intra-hepatic vasculature appear faintly on the left. This is a right gastric vein CPSS entering the post-hepatic caudal vena cava. (b) Repeat portovenogram following temporary occlusion of the shunting vessel. Note the increased opacification of the liver and the lack of contrast medium flow through the abnormal vessel. However, the opacification of the intra-hepatic portal system is poor, and this dog was unable to tolerate a complete attenuation of the shunt. Therefore, a partial suture ligation was performed. (c) Intraoperative portovenogram from the same dog, approximately 3 months after the first surgery. Note the improvement in the intra-hepatic portal blood flow but persistent flow through the CPSS. (d) Repeat portovenogram following temporary occlusion of the shunting vessel. Note the increased opacification of the liver and the lack of contrast medium flow through the abnormal vessel. The dog was able to tolerate a complete ligation of the CPSS at the second surgery. CVC = caudal vena cava; PV = portal vein. © 2020 British Small Animal Veterinary Association

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37.29 A series of ventrodorsal intraoperative mesenteric portovenograms from a 19-week-old male entire West Highland White Terrier with an extra-hepatic congenital portosystemic shunt (CPSS). The images are orientated so that cranial is at the top. (a) Intraoperative portovenogram image. Contrast medium has been injected through a jejunal vein under fluoroscopic guidance with digital subtraction. The majority of the contrast medium, and hence blood, flows through the large shunt vessel (arrowed) on the right of the image. The portal vein and intra-hepatic vasculature appear faintly on the left. This is a right gastric vein CPSS entering the post-hepatic caudal vena cava. (b) Repeat portovenogram following temporary occlusion of the shunting vessel. Note the increased opacification of the liver and the lack of contrast medium flow through the abnormal vessel. However, the opacification of the intra-hepatic portal system is poor, and this dog was unable to tolerate a complete attenuation of the shunt. Therefore, a partial suture ligation was performed. (c) Intraoperative portovenogram from the same dog, approximately 3 months after the first surgery. Note the improvement in the intra-hepatic portal blood flow but persistent flow through the CPSS. (d) Repeat portovenogram following temporary occlusion of the shunting vessel. Note the increased opacification of the liver and the lack of contrast medium flow through the abnormal vessel. The dog was able to tolerate a complete ligation of the CPSS at the second surgery. CVC = caudal vena cava; PV = portal vein.

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37.31

Intraoperative photographs of an exploratory laparotomy in a cat with a congenital portosystemic shunt. (a) The stomach has been retracted caudoventrally to reveal the shunting vessel in the region of the gastric cardia. This is a left gastric vein CPSS entering the post-hepatic caudal vena cava (arrowed). (b) Forceps have been used to carefully dissect around the shunt vessel. The cat tolerated complete attenuation of the CPSS and, therefore, the vessel has been ligated with polypropylene suture material (Prolene; Ethicon) (the second length of suture will be removed prior to routine abdominal closure). © 2020 British Small Animal Veterinary Association

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37.31 Intraoperative photographs of an exploratory laparotomy in a cat with a congenital portosystemic shunt. (a) The stomach has been retracted caudoventrally to reveal the shunting vessel in the region of the gastric cardia. This is a left gastric vein CPSS entering the post-hepatic caudal vena cava (arrowed). (b) Forceps have been used to carefully dissect around the shunt vessel. The cat tolerated complete attenuation of the CPSS and, therefore, the vessel has been ligated with polypropylene suture material (Prolene; Ethicon) (the second length of suture will be removed prior to routine abdominal closure).

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37.32

(a) Ameroid constrictor which consists of a ring of casein with a lumen, surrounded by a stainless steel collar. There is a gap in the ring to allow it to be placed around a vessel and this is closed with a small ‘key’ of casein. In theory the casein absorbs fluid and expands, and the lumen is gradually occluded over a period of weeks. However, it has been shown experimentally that ameroid constrictors cause vessel occlusion primarily by thrombus formation, that this occlusion may be more rapid than desired, and that recanalization of the vessel is possible. (b) Intraoperative photograph of an exploratory laparotomy in a dog with an extra-hepatic congenital portosystemic shunt. An ameroid constrictor has been placed around a portocaval shunt. © 2020 British Small Animal Veterinary Association

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37.32 (a) Ameroid constrictor which consists of a ring of casein with a lumen, surrounded by a stainless steel collar. There is a gap in the ring to allow it to be placed around a vessel and this is closed with a small ‘key’ of casein. In theory the casein absorbs fluid and expands, and the lumen is gradually occluded over a period of weeks. However, it has been shown experimentally that ameroid constrictors cause vessel occlusion primarily by thrombus formation, that this occlusion may be more rapid than desired, and that recanalization of the vessel is possible. (b) Intraoperative photograph of an exploratory laparotomy in a dog with an extra-hepatic congenital portosystemic shunt. An ameroid constrictor has been placed around a portocaval shunt.

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37.35

Exploratory laparotomy in a 6-month-old entire male Labrador Retriever with a hepatic arteriovenous malformation. Note the enlarged hepatic artery supplying the left lateral liver lobe and the dilated portal vein (arrowed). © 2020 British Small Animal Veterinary Association

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37.35 Exploratory laparotomy in a 6-month-old entire male Labrador Retriever with a hepatic arteriovenous malformation. Note the enlarged hepatic artery supplying the left lateral liver lobe and the dilated portal vein (arrowed).

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37.36

Intraoperative image of a cat with peliosis hepatis. The left lateral liver lobe is being resected with the aid of a stapling device. Note the blood-filled cystic lesions affecting the lobe. © 2020 British Small Animal Veterinary Association

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37.36 Intraoperative image of a cat with peliosis hepatis. The left lateral liver lobe is being resected with the aid of a stapling device. Note the blood-filled cystic lesions affecting the lobe.