Hepatic Encephalopathy - Horse

Description

Hepatic encephalopathy is neurological disfunction caused by any acute or severe hepatic insult; 60-80% of hepatic function must be lost before clinical signs develop. A combination of mechanisms is probably responsible for the syndrome.

Signalment

No age, sex or breed predisposions.

There are many hepatic disorders which can lead to hepatic encephalopathy including, Hepatitis, Ragwort Toxicity, Tyzzer's Disease and Hyperlipaemia

Diagnosis

Clinical Signs

Clinical signs vary depending on the severity of hepatic dysfunction, early signs are often subtle and may be missed. Clinical signs may be associated with feeding.

• Depression
• Lethargy
• Head pressing
• Dysphagia
• Ataxia
• Behavioural changes
• Seizures
• Coma
• Death

Clinical signs associated with hepatic disease

• Weight loos
• Diarrhoea
• Icterus

Laboratory Tests

Haemotology and Biochemistry blood results will be consistent with hepatic disease, Increased GGT, SDH Hypoalbuminaemia Elevated bile acids

Biopsy

A liver biopsy can provide a definitive diagnosis of liver disease, a clotting profile should be carried out before taking an ultrasound-guided biopsy.

Ultrasound

Transabodimal ultrasound can be used to assess the structure of the liver and degree of damage.

Pathology

See Hepatic Encephalopathy Pathology

Treatment

With supportive therapy horses may recover from hepatic encephalopathy after 4-21 days. Treatment is only warranted

Sedation is often necessary in cases of hepatic encephalopathy; An alpha 2 agonist at a low dose is usually effective. If the neurological signs are so severe that the horse is a danger to itself and others then immediste euthansia is indicated.

Prognosis

Prognosis is poor to severe but depend on the underlying disease; signs are potentially reversible if the initiating course can be corrected. Horses with hepatic disease showing neurological signs have a poorer prognosis than those showing only signs af hepatic dysfunction. However with appropriate supportive therapy 40% of horses survive for at least 6 months. Recovery may be incomplete and temporary.

References

• Bertone, J. (2006) Equine Geriactric Medicine and Surgery, Elsevier
• Knottenbelt, D.C. A Handbook of Equine Medicine for Final Year Students University of Liverpool
• Merck & Co (2008) The Merck Veterinary Manual (Eighth Edition) Merial
• Rose, R. J. and Hodgson, D. R. (2000) Manual of Equine Practice (Second Edition) Sauders.