# Radiographic Prevalence of Anatomical Variations of the Ventral Lamina of the Sixth Cervical Vertebra, C6/C7 Articular Process Joint Modelling and Competition Outcomes in Warmblood Sport Horses

## TL;DR

This study finds that anatomical variations in the sixth cervical vertebra of warmblood sport horses are common but do not affect performance or joint changes.

## Contribution

The study provides empirical evidence that ECCMV is a normal anatomical variation, not a disease, and does not impact athletic performance in warmblood horses.

## Key findings

- ECCMV was found in 30% of horses and APJ modeling in 32.5%.
- Horses with ECCMV were less likely to show APJ changes compared to those with normal C6 morphology.
- Competition results were not affected by the presence of ECCMV.

## Abstract

Recently, anatomical variations in the shape of the sixth cervical vertebra (C6) have received considerable attention both among equine practitioners and in the equine community. The clinical significance of this finding, referred to as equine caudal cervical morphologic variation (ECCMV), is still controversial. The same applies for alterations in the radiographic appearance of articular process joints (APJ), connecting adjacent vertebrae. Such changes are frequently detected, including in horses without clinical signs. In this study, radiographs of C6 and competition records of 200 clinically sound warmblood sport horses were evaluated. ECCMV and APJ alterations were present in approximately one third of the horses. Statistics yielded no significant association between these findings, but horses with ECCMV were less likely to exhibit radiographic changes in the adjacent APJ. Competition results did not differ between horses with and without ECCMV. These findings suggest that ECCMV is a common anatomical characteristic rather than a disease and does not appear to limit athletic performance in warmbloods.

Anatomical variations of the caudal ventral lamina of the sixth cervical vertebra (C6), referred to as equine caudal cervical morphologic variations (ECCMV), and radiographic modelling of the caudal cervical articular process joints (APJ) are commonly identified in sport horses, yet their interrelationship and relevance for athletic performance remain controversial. This retrospective observational study aimed to determine the prevalence of ECCMV and APJ modelling in a clinically sound warmblood sport horse population, to evaluate a potential association and to assess if ECCMV affects competition performances. Records of 200 warmbloods, presented for pre-purchase examination between 2020 and 2024 were reviewed: the predominant breed was Hanoverian (n = 131), followed by Oldenburg (n = 27) and Holsteiner (n = 22), including 127 geldings, 61 mares and 12 stallions with a median age of 5. ECCMV was diagnosed on latero-lateral radiographs if the caudal ventral lamina of C6 was uni- or bilaterally absent, and APJ modelling at C6/C7 was graded as either normal or mild or moderate to severe. Competition placings and lifetime earnings of each horse were collected from the German National Equestrian Federation database. ECCMV was found in 30% of horses and APJ modelling in 32.5% (mild 26.5%, moderate/severe 6%). There was no significant association between the presence of ECCMV, APJ alterations and competition results, but horses with ECCMV were less likely to exhibit radiographic changes in the adjacent APJ compared to those with a normal C6 morphology (23.3% vs. 36.4%). In conclusion, ECCMV is a common anatomical variation in clinically sound warmbloods, neither predisposing them to APJ modelling nor limiting athletic performance.