Prolonged Visual Evoked Potential Latencies in Dogs Naturally Infected with Canine Distemper Virus

Canine distemper (CD) is a deadly, multi-system infection caused by a Morbillivirus. The canine distemper virus (CDV) frequently affects the nervous system with demyelinating leukoencephalitis, the most common neurological lesion. The disease has been linked to multiple sclerosis (MS) in humans due to similar clinical presentation and pathophysiological mechanisms. In MS, visual evoked potentials (VEPs) have been identified as a reliable marker for disease progression, enabling the early detection of clinically suspected lesions. The aim of this study was to determine if there are any abnormalities in VEP responses in dogs with neurological CD. Visual evoked potentials and electroretinogram (ERG) were recorded at both the cranial and spinal levels in dogs naturally infected with CDV and in healthy dogs. The results in the CDV-infected group revealed a bilateral increase in the latency of N1, P1, N2, P2, and N3 waves of the VEPs, without any alterations in their amplitudes. No significant differences were observed in the ERG between the groups. These results suggest that altered VEP responses could serve as an early diagnostic indicator of neurological damage caused by distemper. Therefore, conducting these studies could potentially aid in the detection of central nervous conduction disorders during the subclinical phases of the disease.