Equine herpesvirus-1 genotype did not significantly affect clinical signs and disease outcome in 65 horses diagnosed with equine herpesvirus-1 myeloencephalopathy.
Authors: Pusterla N, Hatch K, Crossley B, Wademan C, Barnum S, Flynn K
Journal: Veterinary journal (London, England : 1997)
Summary
# Editorial Summary: EHV-1 Genotype and Equine Herpesvirus Myeloencephalopathy Equine herpesvirus-1 (EHV-1) causes neurological disease in horses, and previous research suggested that specific viral genotypes—particularly the neuropathic D752 strain—might predict more severe clinical outcomes; however, this retrospective analysis of 65 horses diagnosed with EHM between 2011 and 2019 challenged that assumption. Pusterla and colleagues reviewed medical records for clinical signs (lethargy, fever, ataxia, urinary incontinence) and outcomes across both D752 and N752 genotype groups, with horses matched for age and sex but showing different breed distributions (notably more Quarter Horses and Saddlebreds in the D752 group). Lethargy, fever, ataxia, and overall disease outcome showed no statistically significant differences between genotypes, though urinary incontinence occurred more frequently in D752-infected horses (P=0.04). These findings suggest that EHV-1 genotype alone may be a poor predictor of myeloencephalopathy severity and prognosis in clinical practice, meaning that case management decisions should remain based on individual clinical presentation and neurological status rather than viral genotyping results—though the increased urinary dysfunction with D752 warrants further investigation into underlying pathophysiological mechanisms.
Read the full abstract on PubMed
Practical Takeaways
- •EHV-1 genotype alone should not be used to predict clinical severity or prognosis in horses with EHM; clinical management should focus on individual presentation rather than genotype
- •Expect urinary incontinence more commonly in horses infected with D752 genotype, which may influence monitoring and supportive care strategies
- •Both D752 and N752 genotypes cause clinically significant myeloencephalopathy requiring equivalent diagnostic and therapeutic approaches
Key Findings
- •EHV-1 genotype (D752 vs N752) did not significantly affect lethargy, fever, ataxia, or outcome in 65 horses with EHM (P > 0.05)
- •Urinary incontinence was significantly more frequent in horses infected with D752 genotype (P = 0.04)
- •No difference in frequency of D752 versus N752 genotypes was found among the 65 EHM cases, contrary to previous studies
- •Breed distribution differed between genotype groups, with Quarter Horses and Saddlebreds overrepresented in D752 group and Warmbloods underrepresented