Viral Hepatitis.

Viral hepatitis in horses has been linked to two viruses identified since 2012, equine parvovirus-hepatitis and equine hepacivirus, which cause acute and chronic liver diseases respectively. Diagnosis is challenging and treatment is mainly supportive as no direct antivirals are available.

Overview of Viral Hepatitis in Horses

• Since 2012, two viruses have been identified as causes of hepatitis in horses.
• These viruses are equine parvovirus-hepatitis and equine hepacivirus.
• Much about their transmission, risk factors, diagnosis, and treatment remains unknown.

Types of Viral Hepatitis and Associated Diseases

• Equine parvovirus-hepatitis:
  • Causes acute hepatic necrosis, a condition characterized by sudden liver cell death.
  • Previously known as Theiler’s disease, a mysterious acute liver failure in horses.
• Equine hepacivirus:
  • Known to cause chronic fibrosing hepatitis, leading to long-term scarring and liver dysfunction.
  • Represents a chronic form of liver disease in horses.

Diagnosis of Equine Viral Hepatitis

• Diagnosis primarily involves exclusion:
  • Ruling out other causes of hepatitis, both infectious and non-infectious.
• Direct detection of the virus:
  • Use of polymerase chain reaction (PCR) testing on serum or liver samples to confirm viral infection.
  • PCR is sensitive for detecting viral genetic material, confirming active infection.

Treatment Strategies and Challenges

• No specific antiviral medications exist for either equine parvovirus-hepatitis or equine hepacivirus infections.
• Treatment is mainly supportive and symptomatic:
  • Addressing liver failure symptoms such as detoxification support.
  • Managing hepatic encephalopathy (neurological complications arising from liver failure) if present.
• The emphasis is on ameliorating clinical signs rather than curing the disease directly.