Theiler’s disease and equine biologics

We will use this report to emphasize the warning against heterologous equine biological products and their use in horses. Tetanus antitoxin jumps to mind and with the use of tetanus vaccine it’s use is not needed. Be sure to vaccinate your horse regularly for tetanus so there is no need for antitoxin.
DrO

Equine Parvovirus Hepatitis
Equine Vet J. 2021 Jun 8.
Authors
Anna Sophie Ramsauer 1 , Marcha Badenhorst 1 , Jessika-M V Cavalleri 1
Affiliation

1 University Equine Clinic – Internal Medicine, Department for Companion Animals and Horses, University of Veterinary Medicine Vienna, Veterinärplatz 1, 1210, Vienna, Austria.

Abstract

Equine parvovirus hepatitis (EqPV-H) was first described in 2018 in a fatal case of Theiler’s disease which followed the administration of an equine-origin biological product. The virus has since been frequently identified in serum and liver tissue of horses affected by Theiler’s disease – an acute, severe hepatitis characterised by fulminant hepatic necrosis with a fatal outcome in most cases. EqPV-H is hepatotropic, appears to be associated with subclinical to severe hepatitis in horses, and is a likely cause of Theiler’s disease. Although this disease is most frequently reported following the administration of equine-origin biological products, it can also occur among in-contact horses. Horizontal transmission may be iatrogenic, via contaminated equine-origin biological products such as equine serum, botulism or tetanus antitoxin, and mesenchymal stem cells, or by means of the oral route of infection. Other horizontal transmission routes, for example arthropod vectors, warrant further investigation. A worldwide prevalence of EqPV-H antibodies and DNA has been reported in asymptomatic horses. EqPV-H-positive horses suffering from acute, severe hepatitis have reportedly developed clinical signs including icterus, lethargy, inappetence, neurological abnormalities, and have had increased liver-associated biochemistry parameters recorded. The most common histopathological abnormalities of the liver have been hepatocellular necrosis, collapse of the lobular architecture, and lymphocytic infiltration. Most horses infected experimentally with EqPV-H have developed subclinical hepatitis and close temporal associations between peak viraemia, seroconversion, and the onset of hepatitis have been observed. Based on strong evidence indicating that EqPV-H causes hepatitis in horses, veterinarians should consider this virus an important differential diagnosis in such cases. Potential risks associated with the administration of equine-origin biological products must be emphasised.

Keywords: Ungulate copiparvovirus 6; EqPV-H; Theiler´s disease; horse; liver; serum hepatitis.