Latent equine herpesvirus-1 in trigeminal ganglia and equine idiopathic headshaking.

BACKGROUND

Trigeminal neuralgia or neuropathic pain has been regarded as a putative cause of idiopathic headshaking in horses. Equine herpesvirus-1 (EHV-1) infection and resultant postherpetic pain have been suggested as a possible cause of such neuropathic pain.

HYPOTHESIS/

OBJECTIVES

To determine the presence of EHV-1 in the trigeminal ganglia of horses with idiopathic headshaking.

ANIMALS: Nineteen horses: control (n = 11, 9 geldings, 2 mares, median age 11 years) and headshaking (n = 8, all geldings, median age 11.5 years) horses were sourced from the equine research herd and caseload at the Veterinary Medical Teaching Hospital.

METHODS

Prospective study to determine the presence of EHV-1 latency in trigeminal ganglia of horses with idiopathic headshaking by real-time PCR detection of the glycoprotein B (gB) gene and the DNA polymerase (ORF 30) gene of EHV-1 in the absence of detectable late structural protein gene (gB gene) mRNA. Control horses were used for comparison. A house keeping gene (equine GAPDH) and positive and negative samples for EHV-1 were used for quality control.

RESULTS

All samples from control horses and 7 of 8 headshaking horses were negative for EHV-1. One headshaking horse tested positive for a single copy of EHV-1 gene.

CONCLUSIONS AND CLINICAL

IMPORTANCE

This study does not support a role for EHV-1 infection and presumed postherpetic pain in the etiopathogenesis of equine headshaking.