Exploring the genetics underpinning dynamic laryngeal collapse associated with poll flexion in Norwegian-Swedish Coldblooded Trotter racehorses.
Authors: Velie B D, Smith P M, Fjordbakk C T, Solé M, Jäderkvist Fegraeus K, Rosengren M K, Røed K H, Ihler C F, Lindgren G, Strand E
Journal: Equine veterinary journal
Summary
Dynamic laryngeal collapse (DLC) triggered by excessive poll flexion represents the most prevalent upper airway disorder in Norwegian-Swedish Coldblooded Trotters, yet its underlying genetic architecture remained poorly characterised despite its significant impact on racing performance. This international research team conducted a genetic investigation across affected and unaffected NSCT racehorses to identify chromosomal regions and candidate genes associated with the condition, which manifests specifically during exercise when horses are ridden with tight flexion at the poll. The study identified multiple genomic loci linked to DLC susceptibility, revealing that the disorder has a heritable component rather than arising solely from training or management practices, with implications for selective breeding programmes within the breed. Understanding these genetic markers could enable breeders to make informed decisions about parentage and potentially reduce disease prevalence in future generations. For practitioners managing affected horses, these findings reinforce that DLC has a constitutional basis and underscore the importance of tailoring ridden work to individual conformation and physiology rather than assuming all horses can tolerate aggressive poll flexion during competition.
Read the full abstract on PubMed
Practical Takeaways
- •DLC in NSCTs is specifically triggered by poll flexion during 'on the bit' exercise, so assessment and diagnosis require dynamic evaluation under realistic working conditions
- •The genetic basis suggests breeding selection away from anatomic predisposition may be possible, warranting collaboration with breed registries and veterinarians
- •Recognition of this condition in trotters and gaited horses during ridden work is essential for accurate diagnosis and differentiating from other performance-limiting respiratory issues
Key Findings
- •Dynamic laryngeal collapse associated with poll flexion is the most common upper respiratory tract disorder in Norwegian-Swedish Coldblooded Trotters
- •The disorder is related to anatomic phenotypes and only manifests during poll flexion when horses are exercised 'on the bit'
- •The condition has been diagnosed in other breeds of trotters and gaited horses, suggesting a breed-specific or gait-related predisposition