47 Questions
What is the normal pathway of blood flow from the spleen, small intestines, pancreas, and stomach?
Portal vein to hepatic sinusoids to caudal vena cava
What is the function of the ductus venosus in the fetal liver?
To bypass hepatic circulation and direct blood to the caudal vena cava
What is the result if the ductus venosus remains patent after birth?
Portosystemic shunt
What is the clinical sign associated with the origin of blood bypassing the liver in PSS?
All of the above
How does the portal vein branch in the dog?
Into right and left branches
Where do the portal vein branches eventually empty into?
Caudal vena cava
What is the most common type of portosystemic shunt?
Extrahepatic shunt with a single portocaval shunt
Which breed of dog is more commonly associated with intrahepatic portosystemic shunts (IHPSS)?
Large breed dogs
What is the role of bile acids in the small intestine?
Aid in lipid absorption via intestinal fat emulsification and metabolism
What is the significance of elevated postprandial bile acids in dogs and cats?
Indicates PSS in 100% of cases
What is the cause of persistent bile acid concentration elevations in animals with PSS?
Shunting of reabsorbed SBA to the systemic circulation
What is the purpose of measuring 6-hour postprandial blood ammonia concentrations?
To increase detection sensitivity of PSS
What is the typical characteristic of ascites in animals with PSS?
Pure transudate with protein content < 2.5 g/dl and cells < 1000/ul
What is the common coagulation abnormality in dogs with PSS?
Prolonged PTT only
What is the typical ultrasound finding in animals with EHPSS?
Small liver
What is the gold standard for PSS diagnosis?
CT angiography
What is the significance of protein C levels in differentiating between PSS and MVD?
Protein C levels are high in MVD and low in PSS
What is the typical histopathological finding in the liver of animals with PSS?
Microscopic bile duct proliferation and hypoplasia of intrahepatic portal tributaries
What is the typical history of dogs with PSS?
Failure to thrive
Which breed is overrepresented for MVD/PVH?
Yorkie
What is the common cause of ascites in HAVM?
Portal hypertension
What is the common complication of PSS in large breed dogs?
GI hemorrhage
What is the result of defective iron transport mechanism in dogs with PSS?
Microcytic, normochromic anemia
What is the common finding in dogs with PSS?
Leukocytosis
What is the result of deficient hepatic urea cycle in dogs with PSS?
Hyperammonemia
What is the common site of stones formation in dogs with PSS?
Kidney
What is the common feature of animals with PVH/MVD?
Present late and are less affected
What is the reason portovenography during laparotomy is not commonly utilized?
It is invasive and requires fluoroscopy
What is the main goal of medical management in dogs with HE?
To quickly lower ammonia levels
What is the effect of lactulose administration in dogs with HE?
It acidifies colonic content, trapping ammonia as ammonium
Why is Supplement K administration important in dogs with HE?
To correct hypokalemia
What is the purpose of antibiotic therapy in dogs with HE?
To reduce bacterial proliferation
What is the benefit of using milk and vegetable proteins in dogs with HE?
They have fewer aromatic amino acids
What is the role of SAMe in medical management of dogs with HE?
It has hepatoprotective, antioxidant, and antiinflammatory properties
What is the goal of surgical management in dogs with PSS?
To promote portal perfusion and reestablish blood flow through hepatic parenchyma
What is a potential complication of complete shunt attenuation?
Portal hypertension
What is the reported survival time in dogs with IHPSS medically managed?
9.9 months
What is the reported complication rate following ameroid constrictor placement for EHPSS?
7-20%
What is a potential benefit of using ameroid constrictors compared to suture ligation?
Reduced surgery times and intraoperative complication rates
What is a characteristic of cellophane band material?
It is inflammatory and causes progressive fibrosis around vessels
What is a potential complication of IHPSS in dogs?
All of the above
What is a reported outcome in dogs with incomplete shunt attenuation after ameroid constrictor placement?
Good to excellent outcomes in 94% of dogs
What is a characteristic of HAVM?
Chronic portal hypertension
What is a goal of post-operative care?
To keep the patient calm and reduce portal hypertension
What is a reported outcome in cats following suture ligation for PSS?
Fair to excellent outcomes in 75% of cats
What is a potential treatment for HAVM?
All of the above
What is a reported median survival time in dogs following ameroid constrictor placement for EHPSS?
152 months
Study Notes
Hepatic Vascular Anomalies
Introduction
- Hepatic vascular anomalies, such as portosystemic shunts (PSS), connect the portal vein to the systemic circulation, bypassing the hepatic sinusoids.
- Normally, blood from the spleen, small intestines, pancreas, and stomach enters the portal vein, perfuses the liver through the sinusoids, and then drains into the hepatic veins and caudal vena cava.
Anatomy and Classification
- Blood from the GI tract, pancreas, and spleen is drained by respective veins, which empty into the portal vein.
- In dogs, the portal vein enters the liver and branches into left and right branches.
- In cats, there are central, right, and left branches of the portal vein.
- PSS can be classified as congenital intrahepatic or congenital extrahepatic shunts.
- Congenital extrahepatic PSS with a single portocaval shunt are most common (66-75% of shunts).
Clinical Signs
- Clinical signs associated with volume and origin of blood bypassing the liver, including:
- Impaired hepatic function
- Hepatic encephalopathy (HE)
- Chronic GI signs
- Lower urinary signs if stones form
- Coagulopathies
- Delayed growth
Hepatic Encephalopathy (HE)
- Most clinical signs seen with PSS are due to HE.
- HE is caused by the inability of the liver to detoxify ammonia and other toxins.
Evaluation
- Congenital EHPSS are more common in small breeds, such as Yorkies, Pugs, and Havanese.
- IHPSS are more common in large breeds, such as Labradors, Wolfhounds, and Golden Retrievers.
- Common symptoms:
- Failure to thrive
- Polyuria and polydipsia (PU/PD)
- Bizarre behavior due to HE
- GI signs
- Dysuria due to ammonium urate calculi formation
- Ascites in HAVM cases
Clinicopathologic Findings
- Mild to moderate microcytic, normochromic nonregenerative anemia
- Leukocytosis associated with poor clearance of bacterial endotoxin
- Low albumin and BUN levels
- Hypocholesterolemia
- Hypoglycemia
- Elevated ALP and ALT levels
- Hyposthenuric or isosthenuric urine and ammonium biurate crystalluria
Liver Function Tests
- 12-hour fasting and 2-hour postprandial bile acids
- Bile acid levels aid in diagnosing PSS.
Treatment
- Medical management:
- Manage HE with lactulose, oral antibiotics, and protein restriction
- Correct coagulopathies and hypoglycemia
- Supplement potassium and vitamin K
- Surgical management:
- Attenuate the abnormal vessel to reestablish blood flow through the hepatic parenchyma
- Goal is to improve clinical signs and control HE
- Surgery may not be possible in all cases, and medical management may be necessary
Prognosis
- Prognosis is dependent on the type of shunt, severity of clinical signs, and response to treatment.
- In some cases, medical management alone can lead to a good prognosis.
- Surgery can improve outcomes, but complications can occur.
This quiz covers hepatic vascular anomalies, specifically portosystemic shunts (PSS) and their connection to the portal vein and systemic circulation. It also touches on the fetal liver's limited capacity for metabolism and detoxification.
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