Equine herpesvirus type 1-associated myeloencephalopathy in The Netherlands: a four-year retrospective study (1999-2003).
Authors: Goehring Lutz S, van Winden Steven C, van Maanen C, Sloet van Oldruitenborgh-Oosterbaan Marianne M
Journal: Journal of veterinary internal medicine
Summary
# Editorial Summary Between 1999 and 2003, Dutch veterinarians documented nine separate outbreaks of equine herpesvirus type 1-associated myeloencephalopathy (EHM) across The Netherlands, providing rare multi-outbreak epidemiological data on this typically sporadic neurological disease affecting the spinal cord. The research team conducted a detailed risk factor analysis across six of these outbreaks, examining how breed, sex, age, fever, and seasonal patterns influenced disease presentation and severity. Key findings revealed a consistent annual occurrence of 2–3 EHM outbreaks nationally, with a marked seasonal association; notably, older horses and female horses demonstrated significantly higher risk of developing severe neurological signs, whilst younger horses (under 3 years) and certain breeds appeared resistant during these outbreaks. The data suggest that susceptibility to EHM involves a complex interaction between genetic factors (breed predisposition), the specific strain of EHV-1 present, and environmental triggers—meaning outbreaks on any given premises cannot be predicted by viral exposure alone. For equine practitioners, this underscores the importance of understanding that outbreak risk varies by population demographics and that vaccination, biosecurity, and monitoring strategies may need tailoring based on the age and breed composition of individual yards.
Read the full abstract on PubMed
Practical Takeaways
- •Veterinarians should maintain heightened clinical suspicion for EHV-1 myeloencephalopathy during peak seasons and in at-risk populations (older, female horses of predisposed breeds)
- •Breed-specific susceptibility and age-related risk factors should inform management strategies and biosecurity protocols during potential outbreak situations
- •Environmental factors combined with viral strain virulence and host factors determine whether EHV-1 infection progresses to neurologic disease on a premises
Key Findings
- •EHM outbreaks occur regularly in The Netherlands at a rate of 2-3 per year
- •Strong seasonal association with EHM outbreaks identified
- •Female horses, aged horses, and specific breeds showed significantly greater risk for severe neurologic disease
- •Horses younger than 3 years and certain breeds were never observed to develop EHM during the study period