Hepatic Encephalopathy in Small Animals and Horses Flashcards
What is hepatic encephalopathy?
Neurological dysfunction that occurs as a result of liver failure secondary to toxic overload
What are the causes of hepatic encephalopathy? Give the animals which these causes are more common for?
Congenital portosystemic shunts
- Common in dogs/cats, rare in horses
Acquired portosystemic shunts
- Can occur in dogs/cats, Does not occur in horses
Fulminant hepatic failure
- Occurs in dogs (cirrhosis, toxicity), Very common in horses
Explain how a portosystemic shunt occurs
Cirrhosis of liver –> Increased pressure in caudal vena cava, which causes build-up of fluid –> fluid channelled through another pathway, back into systemic circulation (non-detoxified blood entering systemic circulation)
What is the pathogenesis (assumed) of HE?
Still debated, complex and multifactorial process
Ammonia definitely involved (likely indirectly)
Acute and chronic HE have different pathogenesis
- CEREBRAL EDEMA occurs in ACUTE HE
- Shunts, cirrhosis associated with chronic HE
Do horses experience chronic or acute HE?
Chronic HE not recognized in horses
What are the clinical signs of HE in small animals?
Intermittent neurological dysfunction - aimless walking, head-pressing, coma
Intermittent GI signs - V/D
Poor growth (DOGS)
PU/PD
Hypersalivation
Behavior changes
Seizures (CATS)
Copper colored irides (CATS)
What are clinical signs of HE in horses?
Primary manifestation is neurological dysfunction
Depression, head-pressing, aimless wandering, yawning, ataxia, seizures, blindness, laryngeal paralysis
What types of shunts are most common in larger breed dogs?
Intrahepatic shunts
What types of shunts are more common in small dogs/cats?
Extrahepatic shunts
What do multiple shunts indicate about the source of the shunts?
Occasionally congenital, but most often secondary to hepatic cirrhosis
Which breeds tend to have a higher occurrence of HE?
Cairn terriers, Irish wolfhounds, Yorkies, Maltese, Australian Cattle Dogs
What is the treatment for HE in dogs and cats?
Surgical - specialist surgery (might be corrected if congenital)
Medical - Diet and gut management, Medium protein diet (white meat and dairy protein), Avoid red meat, Lactulose (complex carb), Abx to reduce gut flora
What is the treatment for HE in horses?
Treat liver failure - shunts do not happen in horses
Sedation, Hypertonic saline/mannitol, Fluid therapy +/- glucose supplementation (liver failure = hypoglycemia), Decrease further GIT toxin production (low protein diet, lactulose)
What would you see on clinical pathology that would indicate HE? What is different between dog and cat values?
Decreased serum albumin/globulin
Cats less likely to have decreased albumin
Dogs more likely to have increased ALT than cats
Cats more likely to have increased ammonia levels
Ammonia concentration increased when fasted
25% of cases have ammonium biurate crystalluria
Hypoglycemia common in smaller dog breeds
