Equine Serum Hepatitis

Also known as:

Theiller's disease

• reported in horses given serum of equine origin
  • tetanus
  • pregnant mare serum
• uknown aetiology
  • suggested it may be of infectious cause, perhaps a virus
• disease manifests itself between one to two months post injection

Clinical

• jaundice
• neurological signs
• death follows quickly

Gross

• jaundice
• ascites
• haemorrhages on and in many organs
• liver is greeenish with reddish and pale blotches
• fibrin strands on the liver surface

Microscopically

• liver cells very fatty (large single vacuoles), some degenerated and a few leukocytes
• moderate portal fibrosis
• heavily bile stained

Description

Equins Serum Hepatitis (ESH) leading to acute liver failure is most commonly associated with administration of an equine biologic product. This is usually tetanus antitoxin, but others such as encephalitis vaccines and equine serum have been implicated.

Signalment

ESH occurs predominantly in older horses. Cases (both individual cases and outbreaks) occur relatively frequently during the autumn months in north western USA.

Clinical Signs

The history may include administration of an equine-derived biologic product. Clinical signs may range from mild lethargy or inappetance to signs of hepatic failure. These may include the following:

• Depression
• Anorexia
• Icterus
• Neurological signs such as head pressing (hepatic encephalopathy)

Clinical signs are generally sudden in onset and rapidly progressive. The course of the disease is usually around five days, with either death or recovery occuring within ten days.

References

• Fox, M and Jacobs, D. (2007) Parasitology Study Guide Part 2: Helminths Royal Veterinary College

• White, N.A., Edwards, G.B. (1999) Handbook of Equine Colic Reed Educational and Professional Publishing Ltd

• Knottenbelt, D.C. A Handbook of Equine Medicine for Final Year Students University of Liverpool

• Edward Robinson, N and Sprayberry, K. A. (2009) Current Therapy In Equine Medicine Sixth edition Saunders Elsevier

• Merck & Co (2008) The Merck Veterinary Manual (Eighth Edition) Merial

• Giles, C.J., Urquhart, K.A. and Longstaffe, J.A. (1985) Larval cyathostomiasis (immature trichonema-induced enteropathy): A report of 15 clinical cases Equine Veterinary Journal 17, 196-201

• Murphy, D., Keane, M.P. and Goulding, R. (1997) Cyathostome associated disease in the horse: investigation and management of four cases Equine Veterinary Journal 9 247-252