Hepatobiliary

Question 1

Describe the main risk factors for development of suppurative cholangitis in cats, and list examples that could cause each

Answer 1

1. Biliary stasis - cholelithiasis, DPM, EHBDO
2. Irregular surfaces conducive to development of biofilms and bacterial inoculation - cholelithiasis, DPM, gallbladder neoplasia
3. Cholelithiasis
4. Sphincter of Odi compromise - pancreatitis, lymphoma, regional duodenitis

Question 2

What are the three pathophysiological mechanisms by which EHBDO can contribute to suppurative cholangitis in cats?

EHBDO = extra-hepatic bile duct obstruction

Answer 2

1. Increased pressure within biliary tract resulting in damage to tight junctions between hepatocytes
2. Decreased Kupffer cell surveillance, resulting in reduced bacterial phagocytosis
3. Interruption of enterohepatic bile flux, resulting in bacterial translocation, reduced IgA in bile, increased endotoxins (since bile acids de-active endotoxins), causing damage to hepatocytes

Question 3

What are the differentials for juvenile hepatopathy?

Answer 3

1. Portosystemic shunts (intra-hepatic and extra-hepatic)
2. Portal vein hypoplasia (includes microvascular dysplasia, and non-cirrhotic portal hypertension)
3. Primary hepatopathy, such as copper hepatopathy, or steroid hepatopathy etc.

Question 4

What different kinds of hepatic vascular anomalies are there?

Answer 4

1. Congenital portosystemic shunts (both intra-vascular and extra-vascular)
2. Portal vein hypoplasia WITH portal hypertension (non-cirrhotic portal hypertension)
3. Portal vein hypoplasia WITHOUT portal hypertension (hepatic microvascular dysplasia)
4. Outflow tract disturbances
5. Acquired portosystemic shunts - secondary to hepatic cirrhosis, or secondary to hepatic arteriovenous malformations

Question 5

Differences between extra-hepatic shunts vs. intra-hepatic shunts

Answer 5

Intra-hepatic shunts - more likely to occur in larger breed dogs (. Generally have a higher proportion of portal blood being shunted, resulting in more severe signs, or earlier onset clinical signs.

Extra-hepatic shunts - more likley to occur in smaller breed dogs

80% of congenital shunts are single vessel (either azgyoys or caudal vena cava). About 25-33% of congenital shunts are intra-hepatic, and 66-75% are extra-hepatic, of which a singular portocaval shunt is most common.

Question 6

Describe how congenital portosystemic shunting results in liver failure

Answer 6

Portal vein is responsible for delivering blood from the abdominal organs to the liver. Important trophic factors, such as insulin and glucagon, are not delivered. This leads to poor hepatic growth, which leads to poor protein production, reticulo-endothelial dysfunction, poor protein and fat meatbolism, hepatic atrophy, and eventually liver failure.

Question 7

What is the association between microvascular dysplasia and macrovascular portosystemic shunts?

Answer 7

58% of dogs and 87% of cats with portal vein hypoplasia without portal hypertension (microvascular dysplasia) have concurrent congenital macroscopic portosystemic shunt.

Question 8

What are the medical management options for animals with portosystemic shunts?

Answer 8

1. Protein restricted diet (may be difficult to balance with needs of a growing puppy) - idea is to reduce accumulation of ammonia
2. Lactulose - laxative which reduces faecal transit time, binds ammonia, produces acidic environment - reduces overall bacterial translocation and reduced ammonia
3. Vitamin B supplementation (vitamin B complex storage relies on liver, which is altered in liver disease)
4. Vitamin K supplementation (if coagulopathy is present)
5. Gastro-protectants (misoprostol, omeprazole) - common for ulceration in intra-hepatic portosystemic shunts, as well as secondary to portal hypertension.
6. SAMe, Ursodeoxycholic acid, Vitamin E, Milk Thistle, L-cartinine

Question 9

Which breeds of dogs are predisposed to copper hepatopathies?

Answer 9

Skye terriers, West Highland White terriers, Doberman pinschers, Labrador Retrievers and Bedlington terriers

Question 10

What are causes for acute hepatitis in dogs?

Answer 10

1. Idiopathic
2. Infectious - CAV 1 (canine adenovirus 1), leptospirosis, Ehrlichiosis, Clostridium spp.
3. Toxins - mycotoxins, aflatoxins, xylitol, cyanobacterium, manganese overdose
4. Drug induced - carprofen, paracetamol, azathiaprine, mitotane, amiodarone

The most common by in large are idiopathic causes

Question 11

What are causes for hepatitis in cats?

Answer 11

1. Neutrophilic cholangitis/ cholangiohepatitis
2. Lymphocytic cholangitis

Infectious causes - typically associated with neutrophilic cholangitis/ cholangiohepatitis. Bacteria, viral (FIV, FeLV, FIP, FCV), fungal