A novel kirkovirus may be associated with equine gastrointestinal disease.
Authors: Haywood Lillian M B, Clark Ava, Hause Ben, Sheahan Breanna
Journal: Equine veterinary journal
Summary
# Editorial Summary: Novel Kirkovirus and Equine Gastrointestinal Disease Whilst infectious causes are suspected in many cases of equine enterocolitis, the responsible pathogen frequently remains unidentified, leaving clinicians without targeted treatment options or biosecurity guidance. Haywood and colleagues employed next-generation sequencing on pooled faecal samples from enterocolitis cases to screen for novel viruses, subsequently validating findings using qPCR across 218 samples collected between 2020 and 2025, stratified into colitis (n=87), colic (n=56) and clinically normal (n=75) groups. A previously unknown kirkovirus was identified in pooled samples from affected horses and showed strong epidemiological association with enterocolitis outbreaks on two farms, with a striking seasonal pattern (autumn through spring) and notable co-occurrence with small colon impactions in 25% of positive cases; reassuringly, the virus was rarely detected in clinically normal populations. Despite these findings, the authors acknowledge a critical limitation—tissue samples from positive cases remain scarce, and attempts to demonstrate the virus directly within gastrointestinal tissues via in situ hybridisation and electron microscopy have been unsuccessful, meaning causality cannot yet be established. For practitioners managing enterocolitis cases or farm outbreaks with seasonal clustering or concurrent small colon impactions, awareness of equine kirkovirus may inform biosecurity protocols and clinical monitoring, though further research is essential to determine whether this virus is a primary pathogen, a secondary opportunist, or an incidental finding associated with gastrointestinal dysfunction.
Read the full abstract on PubMed
Practical Takeaways
- •A novel kirkovirus is associated with farm outbreaks of enterocolitis and small colon impactions; consider this pathogen in differential diagnosis of winter/spring colitis cases
- •The virus shows seasonal prevalence (autumn-spring) which may help guide diagnostic testing and preventive management strategies on affected farms
- •Current evidence does not prove the virus causes disease; further research is needed before specific treatment or prevention protocols can be recommended
Key Findings
- •Next-generation sequencing identified a novel kirkovirus in 5/13 pooled faecal samples from enterocolitis cases with full genome sequencing achieved
- •The novel kirkovirus was associated with enterocolitis in two farm outbreaks but was rarely identified in 75 clinically normal horses
- •All kirkovirus-positive cases presented during autumn, winter, and spring, suggesting a seasonal pattern
- •25% of kirkovirus-positive cases had concurrent small colon impaction