Clinical Virological and Pathological Investigations on Horses With Neurologic Disorders in Turkey

The aim of this study was to investigate the clinical, pathologic, and viral etiology of horses with neurologic disorders. Twelve English Thoroughbred horses with neurologic disorders were investigated for the presence of neuropathogenic equine herpesvirus-1 (EHV-1) and Borna disease virus (BDV) by real-time polymerase chain reaction (PCR) and histopathological methods. Neuropathogenic EHV-1 was detected in the brain of two horses by real-time PCR. Borna disease virus p24 and p40 gene sequences were detected by real-time RT-PCR in the brain of a 3-year-old horse and in the blood of a 1-year-old horse. High fever, ataxia, depression, lack of coordination, and gait abnormalities were present in these horses, which died within a few days of developing neurologic signs. The BDV p24 and p40 real-time PCR products were sequenced and shown to be identical to previously reported BDV sequences. In the brain of the BDV-positive horse, hyperemia was pronounced in the parenchyma and the meninges. In addition, nonpurulent poliencephalomyelitis characterized by perivascular mononuclear cell infiltration was seen. Mononuclear and polymorphonuclear cell infiltration was also seen in the liver with necrotic perihepatitis besides subacute splenitis and glomerulonephritis and severe hyperemia in the kidney and edema and emphysema in the lung. In conclusion, neuropathogenic EHV-1 and BDV were detected in horses from Turkey using molecular detection methods. Since BDV genetic signatures were detected in Turkey for the first time, future epidemiologic studies need to be performed to investigate the range of host animals, spread, frequency, and molecular diversity of BDV; this will allow to determine the risk of this pathogen for Turkish veterinary and public health.