Exploring the genetic influences on equine analgesic efficacy through genome-wide association analysis of ranked pain responses.
Authors: Bacon Elouise K, Donnelly Callum G, Finno Carrie J, Haase Bianca, Velie Brandon D
Journal: Veterinary journal (London, England : 1997)
Summary
# Editorial Summary Genetic variation significantly influences how horses respond to multimodal analgesia, a finding that could reshape individualised pain management protocols and reduce adverse effects associated with standard dosing regimens. Researchers administered hydromorphone and detomidine to 48 horses at standardised intervals and scored analgesic effectiveness (1–3 scale) based on pain response during cerebrospinal fluid collection, then performed genome-wide association analysis to identify genetic variants linked to drug response. Two single nucleotide variants reached statistical significance: one on chromosome 27 within the ADAM5 gene and another intergenic variant on chromosome 29, together explaining approximately 26–32% of the variation in analgesic efficacy, with notably all eight horses demonstrating the poorest pain relief carrying the A/C genotype at the chromosome 29 locus. These findings underscore that analgesic responsiveness is polygenic and multifactorial, yet this preliminary pharmacogenomic evidence provides a foundation for developing genetic screening tools that could enable practitioners to tailor hydromorphone and detomidine dosages to individual horses, thereby optimising analgesia whilst minimising side effects—particularly relevant given the safety concerns both horses and veterinarians face with conventional fixed-dose protocols. Further validation in larger populations will be necessary before clinical implementation, but this work represents meaningful progress toward personalised equine pain management.
Read the full abstract on PubMed
Practical Takeaways
- •Genetic testing for SNVs rs1142378599 and rs3430772468 may help identify horses likely to have poor analgesic responses to hydromorphone and detomidine, allowing proactive dosage adjustment
- •Recognizing that analgesic effectiveness varies significantly between individual horses due to genetic factors supports the case for personalized pain management protocols rather than one-size-fits-all dosing
- •Current findings are preliminary but point toward a future where pharmacogenomic screening could reduce analgesic-related side effects and improve outcomes during procedures requiring pain control
Key Findings
- •Two SNVs (rs1142378599 on chromosome 27 and rs3430772468 on chromosome 29) passed genome-wide significance threshold (P < 1×10⁻⁵) in association with analgesic effectiveness
- •SNV rs3430772468 accounted for 31.72% of explained variation in analgesic effectiveness, with all 8 horses showing lowest analgesic response carrying the A/C genotype
- •All horses with lowest analgesic effectiveness expressed specific genotypes at two SNVs, suggesting genetic predisposition to poor analgesic response
- •Study identifies pharmacogenomic markers that could enable individualized analgesic dosing strategies in horses to minimize side effects