Topic 24 - Vascular liver diseases, portosystemic shunt in dogs and cats. Hepatic encephalopathy Flashcards
Name some vascular liver diseases:
- Portosystemic shunt: can be congenital or aquired
- Portal vein hypoplasia: Can be primary or secondary
- Hepatic arterio-venousus fistula
2+3 causes portal hypertension !!
Portosystemic shunt
Definition:
Consequences:
Definition: Abnormal vascular connection between portal vein to the systemic circulation, not going by the liver for filtration and detoxification.
Consequences:
1. Toxins are not filtered, and accumulates in the body via systemic circluation = hepatic encephalopathy, delayed growth, impaired hepatic function
2. Lacking blood flow and hepatotropic factors(insulin, gluacgon) and the liver becomes underdeveloped and proteins are not produced
How to diagnose portosystemic shunt
- CBC: high WBC, hypoproteinaemia
- Urine: decreased SG, ammonium-biurate stones
- Ultrasound: To localise and decide which type of shunt: extrahepatic or intrahepatic
SG= Specific Gravity
Congential Portosystemic shunt
Can be both intrahepatic (large breed) or extrahepatic (small breed)
There is an abnormal embryonic vessel present from birth, 75% are congenital and problems occur in young animals
Congential is wide and short
Causes portal HYPOtension
Intrahepatic portosystemic shunt
Persistent ductus venosus
= There is a direct connection between the portan vein and vena cava, meaning the portal circulation skips the detoxification on the hepatocytes. It doest not reach the central vein, but goes stright to vena cava
Large breeds
A = normal
B = Intrahepatic portosystemic shunt
Normal closure of ductus venosus
Functionally after 3 days, anatmoically after 15-18 days
Irish wolfhound anatomically after 3 months !!
Extrahepatic portosystemic shunt
= Abnormal anatomical connection between the portal system and the vena cava, blood supply from abdominal organs
There are different types, depending on where the abnormality is
Small breeds
A = Normal
B = Intrahepatic portosystemic shunt
C = Extrahepatic portosystemic shunt
Name the abnormalities for extrahepatic portosystemic shunt
- Portocaval: portal vein ⭢ caudal vena cava
- Portazygo: Portal vein ⭢ azygos and back to vena cava
- Gastrocaval: Left gastric vein ⭢ vena cava
- Gastroduodenocaval: Duodenal blood supply skips portal vein, ⭢ vena cava
- Splenocaval: Splenic vein skips portal vein, ⭢vena cava
Acquired portosystemic shunt
Aquired is narrow, twisting and trorurous, a result of portal HYPERtension
Mostly seen in older animals.
Mostly extrahepatic !!
What happens in case of acquired porotsystemic shunt?
We have a portal hypertension, causing a protective compensatory process which will reopen the shunts - but they will not be functional but a recanalisation occur.
Portal vein hypoplasia
= microscopic malformation of the hepatic vasculature.
Can be primary or secondary
Primary Portal vein hypoplasia
Types
Idiopathic non-cirrhotic portal hypoplasia: with portal hypertension
Hepatic microvascular dysplasia: no portal hypertension
Hepatic microvascular dysplasia
Definition:
Occurence, age/breed:
Clinical signs:
Definition: Special form of congenital hypoplasia of the portal vein, there is no hypertension
Occurence, age/breed: Cairn terriers, yorkshire terriers
Clinical signs: Subclinical or signs: ascites, mild CPSS
Secondary hepatic microvascular dysplasia
Portal vein occlusion
Arterioportal fistula
Definition
Communication between the hepatic artery and the portal vein.
Hepatic artery connects the arota to liver (oxygen), portal vein connect the GIT and spleen to liver (nutrients). This leas to a retrograde blood flow into the portal system causing a portal hypertension which will cause ascites, GI oedema
Large, distended, pulsating vessel
Arterioportal fistula
Diagnosing
Treament
Diagnosing: Ultrasound: distended, pulsating portal braing
Treament: Lobectomy, portal hypertension treatment
Hepatic encephalopathy
Definition:
Causes:
Definition: Reversible, metabolic dysfunction of the brain and CNS. A syndrome caused by liver dysfunction
Causes:
- Portosystemic shunt
- Liver dysfunction
Hepatic encephalopathy
Grades:
Grades:
1. Lethargy, apathy, depression, personality chnges, anorexia, PU
2. Ataxia, disorientation, pacing or circling, head pressing, blindness, salivation
3. Stupor, severe salivation in cats, seizures
4. Coma, non-responsive
What happens in the body in case of hepatic encephalopathy?
⭡ of ammonia in blood, it crosses the BBB, casing ⭡ammonia and ⭡glutamine in the brain which again causes brain oedema
Type of hepatic encephalopathy
Acute
Chronic
What makes it acute or chronic hepatic encephalopathy?
Acute = Acute ⭣ of liver function
Chronic = PSS + ⭣liver function
In cats: hepatic lipidosis causes chronic hepatic encephalopathy
Acute hepatic encephalopathy
Occurence:
Causes:
Clinical signs:
Occurence: rare, 5%
Causes:
1. Acute, fulminant liver failure
2. By toxin, infection, drug, sichaemia
3. Response to SIRS (Systemic Inflammatory Response Syndrome)
Clinical signs: Stages 3-4: seizures, coma, non-responsice
Chronic hepatic encephalopathy
Occurence:
Occurence: More common, 95%
Better prognosis if the liver issues are reversible: fibrosis, no cirrhosis.
Can be seen in Cats with hepatic lipidosis
How to diagnose hepatic encephalopathy
- CBC: mild regenerative anamie, elevated liver enzymes, increased bile acids, decreased albumin and cholesterol, increased ammonia!!!
- Urine: PU/PD, alkaline pH, crystals in urine
