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Alimentary > Icterus in the Horse > Flashcards

Icterus in the Horse Flashcards

1
Q

Causes of haemolysis in horses…

A 
Neonatal isoerythrolysis
Infections EIA
Drugs: penicillin
Toxins: onion
IMHA
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2
Q

What is the most common cause of haemolysis in foals?

A

Neonatal isoerythrolysis

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3
Q

What are the most common causes of hepatic icterus in horses?

A

Anorexia

Acute hepatocelluar diease

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4
Q

Describe how anorexia causes hepatic icterus in the horse…

A

Shortage of ligandin

Protein responsible for uptake of unconjugated bilirubin into the liver –> release stimulated by eatin

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5
Q

Causes of post hepatic icterus in the horse…

A

Cholelithiasis
Cholangitis
Cholangiohepatitis
Indicated cholestasis if conjugated bilirubin >30% total

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6
Q

What should you think if the icteric horse isn’t anorexic, a foal or pale?

A

Liver disease

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7
Q

What are the main functions of the liver?

A 
Protein metabolism
Carbohydrate metabolism
Lipid metabolism
Detoxification
Immune system
Bile excretion
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8
Q

Common clinical signs of liver disease in the horse…

A 
Depression
Anorexia
Colic 
\+ Hepatocellular swelling
\+ Biliary obstruction 
Abnormal behaviour
Weight loss
Icterus

Less common:
Ascites
D+
Oedema

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9
Q

What is phylloerythrin?

A

Photodynamic agent formed by bacteria in the gut and absorbed, conjugated and excreted by the liver

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10
Q

What is photosensitisation?

A

Increased levels of phylloerthrin become lodged in peripheral tissues due to liver dysfunction

Exposure to UV light causes cell membrane damage and necrosis

Lesions occur in areas of non-pigmented skin

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11
Q

Is photosensitisation reversible?

A

Yes as long as the underlying cause is fixed

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12
Q

What can be used to diagnosed liver diease in the horse?

A

Clinical signs
Blood work
US
Biopsy

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13
Q

What 3 things are particular helpful to look at on blood results that indicate liver disease in the horse? Why?

A

Bile acid
SDH
GGT
These are specific to the liver so don’t have any other body system associations

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14
Q

What can you look at on US of the liver?

A

General size
Changes in echogenicity
Diluted bile ducts, choleliths, abscesses, neoplasia

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15
Q

What can a hepatic biopsy provide information about?

A

Diagnosis
Prognosis
Treatment options

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16
Q

What are the treatment options for hepatic disease in the horse?

A 
Primarily supportive
Correct fluid deficits and acid-base balance
Provide IV glucose if horse is anorexia
ABs if suspect bacterial involvement
Anti-inflammatories
17
Q

What are the treatment options for hepatic encephalopathy in the horse?

A

Sedation
Mannitol/hypertonic saline (for cerebral oedema)
Oral lactulose - limit ammonia absorption
Oral branch AAs

18
Q

What needs to be remembered about sedation given to horses with hepatic encephalopathy?

A

Most sedation is metabolised by the liver so can have longer or shorter action than expected

19
Q

What dietary modifications are available for horses with hepatic encephalopathy?

A

High CBO, sufficient quality protein

  • Sugar beet
  • Cracked corn
  • Molasses
  • Meadow hay
20
Q

What anti-inflammatories can you give to a horse with HE?

A

NSAIDs - Flunixin
DMSO
Steroids
Pentoxifylline

21
Q

What are liver diseases seen in horses?

A

Pyrrolizidine alkaloid toxicity

Cholangiohepatitis

22
Q

Explain the aetiology of PA toxicity…

A

Ingestion of plants containing PA e.g. ragwort
Ingestion from hay/pasture
Usually unpalatable
Long term ingestion (4-12 weeks)

23
Q

Explain the pathogenesis of PA toxicity in horses…

A

PA metabolised by liver to toxic derivatives
Pyrroles are antimitotic: cross link DNA and bind to nucleic acid and proteins within hepatocytes
Cells cannot divide -> megalocyte production –> megalocyte death –> fibrosis

24
Q

How would you diagnose PA toxicity?

A

Clinical signs
History of ingestion
Blood work
Biopsy

25
Q

What is the treatment and prognosis for PA toxicity?

A

No specific treatment
Poor prognosis
Death within 10 days of clinical signs of liver failure
Regeneration not possible with fibrosis

26
Q

What increases the risk of hyperlipaemia in horses?

A

Seen in Shetlands, miniature and other pony breeds

Increased risk if obese

27
Q

Why does hyperlipaemia occur?

A 
NEB
\+ Disease
\+ Stress
\+ Pregnancy
\+ Lactation

Excessive triglycerides in the liver due to excess fatty acid delivery (Causes hepatic lipidosis)

28
Q

What are the clinical signs of hyperlipaemia?

A 
Lethargy
Anorexia
Weakness
Icterus
Mild colic, D
Recumbency
Liver dx
29
Q

How would you diagnose hyperlipaemia in the horse?

A 
Breed
History
Clinical signs
Measure tri levels in serum
Liver biopsy
30
Q

What is the treatment for hyperlipaemia in the horse?

A

Reverse negative energy balance

  1. Encourage to eat
  2. Enteral nutrition
  3. Parenteral nutrition

Treat hepatic disease
1. Supportive therapy

Eliminate stress/treat concurrent disease

  1. Wean foal
  2. Specific treatment for primary disease

Inhibit further fat mobilization

  1. Restore positive energy balance
  2. Insulin (inhibits hormone sensitive lipase

Increase triglyceride uptake by peripheral tissues
Heparin increases activity of lipoprotein lipase

31
Q

What is the prognosis for hyperlipaemia?

A

Poor once severe clinical signs become apparent

32
Q

How can you prevent hyperlipaemia in the horse?

A

Monitor at risk animals
Measure tris levels in sick pony, ensure adequate nutrition
Prevent obesity

33
Q

What are the possible causes of acute hepatitis in the horse?

A 
Theiller's disease
Bacterial (Tyzzer's disease)
Toxic
Viral
Parasitic
34
Q

Explain the pathogenesis of cholithiasis/cholangiohepatitis in the horse..

A

Cause of stone formation:
Parasites
Ascending biliary infection or inflam
Biliary stasis

35
Q

What are the clinical signs of cholelithiasis/cholangiohepatitis?

A

Fever
Icterus
Colic
Strongly suggestivr

36
Q

What is Theillier’s disease?
Diagnosis?
Treatment?
Prognosis?

A

Widespread hepatic necrosis (small liver at post mortem).

Diagnosis:

  1. History
  2. Abrupt onset of clinical signs
  3. Evidence of hepatic insufficiency
Treatment = no specific
Prognosis = poor
37
Q

What is Tyzzer’s disease?
Clinical signs?
Treatment?
Prognosis?

A

Infectious hepatitis in horses (Chlostridium piliformis)

Only seen in foals 7-42 days old

Clinical signs:

  1. None - found dead
  2. Non-specific
  3. Loss of suckle, depression, recumbency

Treatment:
Antibiotics
Supportive therapy
(Only one report of successful treatment)

Prognosis = grave

38
Q

Cholelithiasis (gallstones) in horses
Diagnosis?
Treatment?
Prognosis?

A

Diagnosis:
Liver enzyme activity (GGT, SDH, AST)
Ultrasound = dilated bile ducts, cholelith
Biopsy

Treatment:
Antimicrobials
Supportive care
DMSO
Anti-inflammatories

Prognosis = depends on fibrosis and number of choleliths

39
Q

What is prognosis of liver disease primarily based on?

A

Degree of fibrosis

Alimentary (14 decks)

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