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==Description==

==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 encephalitis vaccines and equine serum have also been implicated. Other possible hypotheses include alkaloid toxicity and mycotoxins.   

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 encephalitis vaccines and equine serum have also been implicated. Other possible hypotheses include alkaloid toxicity and mycotoxins. Several cases have been reported in which no biologic product had been administered, leading to the possibility that an infectious agent may be involved.   

==Clinical Signs==

==Clinical Signs==

The history may include administration of an equine-derived biologic product, often four to six weeks prior to the onset of clinical signs. These may range from mild lethargy or inappetance to signs of acute or chronic hepatic failure. They 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.  

The history may include administration of an equine-derived biologic product, often four to six weeks prior to the onset of clinical signs. These may range from mild lethargy or inappetance to signs of acute or chronic hepatic failure. They are generally sudden in onset and rapidly progressive. The course of the disease is usually around five days, with death ususally occuring within ten days.  

Signs may include the following:

Signs may be non-specific such as depression or anorexia. Affected horses are often severely icteric and may pass dark urine due to the presence of bilirubin. Signs relating to hepatic encephalopathy may be present, such as head pressing, excitement, yawning or aimless wandering.

 

* Neurological signs such as head pressing (hepatic encephalopathy)

Mild forms of the disease have also been reported, characterised by a mild malaise and increased serum hepatic enzyme concentrations.  

Mild forms of the disease have also been reported, characterised by a mild malaise and increased serum hepatic enzyme concentrations.  

==Pathology==

==Pathology==

Post mortem examination often shows the liver to be enlarged and pale with rounded edges. Generalised icterus is often present. Histologically there may be centrilobular necrosis with mononuclear cell accumulation within the portal triads.

Post mortem examination often shows the liver to be enlarged and pale with rounded edges. Generalised icterus is often present. Histologically there may be centrilobular necrosis with mononuclear cell accumulation within the portal triads. Contusions, lacerations or fractures may be present if the disease has had a violent clinical course.  

==Prognosis==

==Prognosis==

 

 

==Prevention==

==Prevention==

==References==

==References==

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

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

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

* 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''  

* Lavoie, J. P., Hinchcliff, K. W. (2009) '''Blackwell's Five-Minute Veterinary Consult: Equine''' ''Wiley-Blackwell''

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

* 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''

* Smith, H. L., Chalmers, G. A., Wedel, R. (1991) '''Acute hepatic failure (Theiler's disease) in a horse''' ''Canadian Veterinary Journal 32, 362-364.