Authors: May-Davis Sharon, Dzingle Diane, Saber Elle, Blades Eckelbarger Pamela
Journal: Animals : an open access journal from MDPI
Summary
# Editorial Summary: Cervical Vertebral Anomalies in Modern Horses Researchers examined skeletal specimens to characterise anatomical variations of the sixth cervical vertebra (C6) in contemporary horses, specifically focusing on absent or partially absent tubercles—bony projections that serve as attachment points for critical stabilising muscles. Using a systematic grading protocol across 76 C6 specimens, they documented the prevalence and severity of these defects, finding that left-sided absence of the caudal ventral tubercle was most common (35 cases), with complete bilateral absence occurring in 29 horses. Significantly, complete absence of the caudal tubercle (present in 56 specimens) was strongly associated with concurrent absence or reduction of the cranial tubercle, suggesting a coordinated developmental anomaly rather than independent variations. The functional implications are substantial: these morphological changes—which occasionally caused the C6 to resemble the C5 vertebra above it—would compromise attachment sites for the longus colli muscles, muscles essential for neck stability and proprioceptive control. Equine professionals managing horses with diagnosed equine complex vertebral malformation (ECVM) or those exhibiting cervical instability should be aware that these anatomical variants may represent heritable defects warranting further investigation into their genetic basis and their relationship to clinical signs including ataxia, proprioceptive deficits, and performance limitations.
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Practical Takeaways
- •ECVM with absent ventral tubercles in C6 may compromise cervical stability and caudal cervical muscle function, potentially affecting athletic performance and predisposing horses to neck-related dysfunction
- •Recognition of this vertebral malformation pattern is important for veterinary assessment of horses with cervical issues, as it represents a structural limitation affecting muscle attachment and biomechanics
- •Further research into the genetic basis and clinical significance of ECVM is needed to inform breeding decisions and early identification of affected horses
Key Findings
- •Left unilateral absent CVT was most prevalent (n=35), followed by bilateral (n=29) and right unilateral (n=12) presentations
- •Complete absence (4/4 grade) of CVT occurred in 56/76 specimens with p=0.0013 significance
- •Of specimens with 4/4 grade aCVT, 41/56 showed partial absence of the cranial ventral tubercle with left p=0.00001 and right p=0.00018 significance
- •Bilateral C6 specimens displayed morphological resemblance to C5, suggesting homeotic transformation that compromises attachment sites for cranial and thoracal longus colli muscles