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44 Cards in this Set

  • Front
  • Back

How much of cardiac output does the liver receive?

1/3-1/2

What are the two general patterns of liver disease? What is each susceptible to?

Periportal pattern (zone 1) - susceptible to toxins


Centrilobar pattern (zone 3) - susceptible to ischemic injury

How much of the liver may be damaged before you see signs of hepatic insufficiency?

80%

What are the most common signs of hepatic disease in horses?

Depression


Anorexia


Colic


Icterus (may have pigmenturia)


Hepatic encephalopathy

What is icterus?

An accumulation of bilirubin in the tissues.


May be due to failure of uptake, conjugation, or excretion of bilirubin.




Other pigments may also cause yellow discolouration.

What can cause hepatic encephalopathy?

Hepatic insufficiency or shunting of blood past the liver (portosystemic shunts are rare in horses).


Will have hyperammonemia and aromatic amino acids in the blood (act as neurotransmitters and increase inhibitory NTs at GABA receptors)

What are the clinical signs of hepatic encephalopathy?

Depression


Drastic behaviour change


Ataxia, paresis


Aimless wandering


Head pressing


Yawning


Grimace


Stupor/coma

What tools are useful to evaluate a suspected hepatic encephalopathy horse?

Clinical pathology


Ultrasound


Biopsy


(others)

What liver enzymes are most useful to measure in horses?

SDH


GLDH (not commonly done)


AST


Arginase

What are the two cholestatic enzymes?

GGT


ALP

What is bilirubin? What would tell you that there may be hepatobiliary disease?

Bilirubin - a normal metabolite of heme formed in macrophages.


An increase in conjugated bilirubin to more than 25% of total bilirubin is consistent with hepatobiliary disease (so need to measure conjugated and unconjugated).

What test is useful for indicating hepatic function in the horse?

Bile acids!

Describe the expected changes with liver disease for albumin, globulins, clotting time, BUN/ammonia, and glucose.

Albumin - decreased with very chronic liver disease


Globulins - increased (inflammation)


Clotting times - prolonged (factors 2, 7, 9 10 made in liver)


BUN - decrease


Ammonia - increase


Glucose - decreased

What might you see on ultrasound of a diseased liver?

Prominent vascular pattern (portal veins with prominent fibrous tissue lining (white circles) vs hepatic veins)


Likely won't see bile ducts


Limitations: ribs, depth/size of liver, abdominal viscera

Describe principles of taking a liver biopsy.

First: do a pre-biopsy coagulation profile! PT, APTT.


Ultrasound-guided biopsy is best


Use a 14g TruCut biopsy needle


Send it for histopathology and culture.

In general, how do you treat liver disease?

Mostly supportive care.


Fluids (dehydration, acid/base abnormalities, electrolytes)


Nutritional supplementation


Decrease toxin production/absorption from gut


Anti-inflammatories


Manage hepatic encephalopathy

Describe a "traditional liver diet" for a horse.

Low protein


High carbohydrates


Rich in branched-chain amino acids


+ grass hay


Fed in multiple small meals (help maintain blood glucose)

What can you use to help decrease production and absorption of toxins?

Mineral oil


Magnesium sulfate


(these two decrease transit time, and reduce the time for bacteria to produce ammonia, or for the gut to absorb it)


Oral antibiotics to decrease NH4 absorption (metronidazole, lactulose? listed but not an abx)

Why should you avoid giving diazepam to sedate a horse with hepatic encephalopathy?

Hepatotoxic


Can cause excitation alone


ACTIVATES GABA - things will get so much worse!!

Name three other supportive medications that can be used to treat liver disease.

Sam-e


Pentoxyfylline


Milk thistle

What's the best way to determine prognosis for liver disease?

Severity of clinical signs

What causes acute hepatitis in horses?

Unknown but has been linked to...


- Equine serum products


- Viruses


- Hepatotoxic substances


- Type III hypersensitivity

What are the clinical signs of acute hepatitis?

(Typically in adults)


Anorexia


Acute depression


Other CNS signs (including hepatoencephalopathy)


Icterus


"Colic"

How can you diagnose acute hepatitis?

History of an equine-origin biologic


Clinical signs


Bloodwork


Biopsy (widespread necrosis, centrilobular)


Necropsy

How do you treat acute hepatitis? What's the prognosis?

Treatment: nonspecific, hepatosupportive. May need sedation to control mania.


Prognosis: often stabilize within 2 days, with supportive care. Prognosis is poorer if severe HE, hemorrhage, hemolysis, or if mania persists through sedation.

What is the causative agent of Tyzzer's disease?

Clostridium piliformis

What are the clinical signs of Tyzzer's disease?

(Note: typically in foals 9-30 days)


Acute depression


Icterus


Fever


Anorexia


Diarrhea


Seizures/coma


Rapid progression to death

How can you diagnose Tyzzer's disease?

Antemortem:


- Age, clinical signs


- Icterus, increased liver enzymes, bile acids, bilirubin


- Biopsy (and maybe RT-PCR)


Postmortem:


- Hepatomegaly


- Multifocal miliary hepatic necrosis


- Organisms demonstrated with silver stain

How do you treat Tyzzer's disease?

Antibiotics: tetracycline, penicillin, or TMS


Supportive care


Parenteral nutrition




Note: peracute death common, so treatment is rarely effective

What is cholangiohepatitis?

Inflammation of the bile passages and adjacent liver parenchyma.

What are the suspected etiologies of cholangiohepatitis?

Ascending infection


Parasite migration


Chronic biliary stasis


Biliary reflux

What are the clinical signs of cholangiohepatitis?

Pyrexia


Colic


Icterus


Chronic, significant weight loss

How do you diagnose and treat cholangiohepatitis?

Dx: liver biopsy (histopath, culture)


Tx: systemic antibiotics


- long course


- primarily g- bacteria from the gut


- support liver function and treat underlying disease

What are some plants that contain pyrrolizidine alkaloids?

Amsinckia intermedia


Senecio spp


Crotalaria spp

What are the clinical signs of pyrrolizidine alkaloid toxicosis?

Depression


WEight loss


Icterus


Photodermatitis


Hepatoencephalopathy

How do you diagnose pyrrolizidine alkaloid toxicosis?

History (walk the field!)


Bloodwork suggestive of liver disease


Biopsy (megalocytosis is pathognomonic)

How can you treat pyrrolizidine alkaloid toxicosis? What's the prognosis?

Tx: Supportive treatment, and treat asymptomatic animals. Remove others from the field.


Prognosis: poor. Often die 5-10 days after signs appear.

What's the toxin in alsike clover?

Suspected... sooty blotch (Cymadothea trifolii), a fungal plant pathogen. May see black, irregular lesions on the back side of leaves.

What are the clinical signs of alsike clover toxicity?

Photosensitization


Liver failure (and associated signs)


Nervous/digestive disorders (colic, diarrhea, oral lesions)

In what animals is hepatic lipidosis more common?

Miniature horses


Donkeys (mini and normal)


Adult horses (esp if obesity, weight loss, stressful events, or anorexia)

Describe the pathogenesis of hepatic lipidosis.

Decreased carbohydrate availability > energy from fatty acid oxidation > overwhelmed liver gluconeogenesis > ^^triglyceride storage




Things that increase removal of fatty acids from adipose tissue: increased glucocorticoids, increased glucagon, decreased insulin

What are the clinical signs of hepatic lipidosis?

Icterus


Anorexia


Weakness/ataxia


Severe depression


Recumbency


Diarrhea


Mild abdominal pain


Fever


Dependent edema

How can you diagnose hepatic lipidosis?

Bloodwork (hepatic panel, lipids/triglycerides)


Ketonuria


Ultrasound


Biopsy

How do you treat hepatic lipidosis?

Improve energy intake and balance


Treat hepatic disease


Eliminate stress/treat concurrent disease


Inhibit fat mobilization from adipose (insulin)


Increase triglyceride uptake in tissues (heparin)