Prevalence of asinine herpesvirus type 5 (AsHV-5) infection in clinically normal Lipizzaner horses.
Authors: Rushton James Oliver, Kolodziejek Jolanta, Nell Barbara, Nowotny Norbert
Journal: Veterinary journal (London, England : 1997)
Summary
# Editorial Summary: AsHV-5 in Lipizzaner Populations AsHV-5 has largely been overlooked in equine practice, with infection assumed rare in horses, yet this 18-month surveillance study of 266 clinically normal Lipizzaners uncovered a notably higher prevalence than documented in the literature. Using serial sampling of blood mononuclear cells alongside nasal and conjunctival swabs analysed via nested PCR and sequence verification, researchers identified AsHV-5 in 39 animals (15% of the population), with 51 positive samples suggesting some horses carried the virus intermittently or persistently. Infection status showed no correlation with age, sex, or geographical location within these closed studs, indicating widespread subclinical exposure rather than outbreak patterns. The practical implication for equine professionals is significant: AsHV-5 may be substantially more prevalent in horse populations than currently appreciated, warranting consideration in diagnostic protocols when herpesvirus PCR testing proves positive but EHV-2 and EHV-5 are ruled out, particularly in cases of respiratory or reproductive disease where aetiology remains unclear. Understanding this virus's epidemiology and pathogenic potential in horses remains critical, especially given evidence of cross-species transmission from donkeys.
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Practical Takeaways
- •AsHV-5 is circulating in clinically normal Lipizzaner populations and may be more common than previously recognized—practitioners should consider this virus in differential diagnoses even without clinical signs
- •The lack of correlation with age, sex, or location suggests widespread endemic circulation in closed herds rather than risk-factor-dependent infection
- •Routine screening protocols may underestimate AsHV-5 prevalence if not specifically targeted, as standard EHV PCR assays will miss this virus
Key Findings
- •AsHV-5 infection detected in 39 of 266 clinically normal Lipizzaner horses (14.7%) via PCR of peripheral blood mononuclear cells and nasal/conjunctival swabs
- •51 positive samples collected over 18 months from seropositive animals, indicating persistent or recurrent subclinical infection
- •No statistically significant association between infection status and animal age, gender, or geographical location within the closed population
- •Subclinical AsHV-5 infection appears more prevalent than previously reported in the literature