Incidence of variations of the transverse processes of the sixth and seventh cervical equine vertebrae

Gerlach, Kerstin; Schad, P; Offhaus, J.; Brehm, Walter; Pelli, Anna

doi:10.21836/pem20210606

Cited by 3 publications

(13 citation statements)

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“…The mounting concern in the horse community of congenital malformations in the cervicothoracic region known as ECVM has a plethora of equine researchers examining the complexities associated with this condition [ 11 , 12 , 13 , 14 , 15 , 16 , 17 , 18 , 20 , 21 , 22 , 23 , 25 , 29 , 34 , 35 ]. This manuscript examined one such complexity not yet studied, notably, the association in grades of C6 aCVTs and aCrVTs to the anomalous transposition, whether complete or incomplete, on the ventral surface of C7 and the replication of transverse foramen.…”

Section: Discussionmentioning

confidence: 99%

“…As reported in the incidental findings, these transpositions coincide with longus colli variations, confirming May-Davis and Walker’s (2015) previous findings [ 22 ]. Yet, the bifurcation of the scalene muscles, relocation of brachial plexus nerves, and subsequent pathways might explain some of the clinical concerns raised by previous authors when the patient appears symptomatic of neck pain, thoracic limb ataxia, and/or forelimb paresis and paresthesia [ 16 , 17 , 22 , 23 , 29 ]. These concerns might also include the absent fovea costalis caudalis , relative to the first sternal rib, where associative malformations have previously been reported [ 13 , 23 , 36 ], and the asymmetric transverse processes through uneven biomechanical load.…”

Section: Discussionmentioning

confidence: 99%

“…Primary nomenclature was derived from Getty [ 26 ] and the previous literature describing the grading of the aCVT of C6 and transposition of the aCVT onto the ventral surface of C7 [ 14 , 15 , 16 , 17 , 18 , 19 , 25 , 29 ].…”

Section: Methodsmentioning

confidence: 99%

“…Furthermore, horses with an aCVT, whether partial or complete, could transpose one or both tubercles onto the ventral surface of C7 and replicate the transverse foramen from C6 [ 14 , 15 , 16 , 17 , 18 , 19 , 28 ]. Some authors have described this transposition on C7 as a “protuberance” [ 29 ], while others referred to it as a “transposed CVT from C6” [ 12 ], “transposed ventral lamina from C6” [ 16 ], or a “malformation with anomalous shape of C7” [ 17 ]. To date, studies describing the corresponding replication of the transverse foramen onto C7 [ 12 , 13 ] have not identified an associative frequency with the aCVT of C6, the presence of a transposition on C7, nor similarity in size.…”

Section: Introductionmentioning

confidence: 99%

“…To date, studies describing the corresponding replication of the transverse foramen onto C7 [ 12 , 13 ] have not identified an associative frequency with the aCVT of C6, the presence of a transposition on C7, nor similarity in size. In general, authors agree on the terminology of the foramen with a few modern variants—arterial foramen or transverse foramen—while the Latin foramen transversarium is more commonly used in veterinary and older texts [ 26 , 29 , 30 ]. The significance here is that in the normal state, paired transverse foramen are present from C1 to C6 but are not present in the normal morphology of C7 [ 26 ], thus raising concerns as to whether the associative blood vessel is also deviated as per the longus colli and scalene ventralis muscles previously described in ECVM [ 22 , 23 ].…”

Section: Introductionmentioning

confidence: 99%

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Characterization and Association of the Missing Ventral Tubercle(s) from the Sixth Cervical Vertebra and Transpositions on the Ventral Surface of the Seventh Cervical Vertebra in Modern Equus ferus caballus

May-Davis,

Eckelbarger,

Dzingle

et al. 2024

Animals

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In recent years, equine complex vertebral malformation (ECVM) has been of concern in the equine community, with studies identifying numerous associative morphological variations. Here, we examine the morphological association between C6 and C7 for dependency in ECVM cases, where the partially absent ventral process of C6 transposes on the ventral surface of C7. A C6 ventral process presents two tubercles, one cranial (CrVT) and one caudal (CVT). In this study, the C6 osseous specimens (n = 85) demonstrated a partial or completely absent CVT (aCVT) graded 1–4 that often extended cranially creating a partially absent cranial ventral tubercle (aCrVT) graded 1–3. In the 85 C6 osseous specimens examined, the corresponding C7s demonstrated either a complete or incomplete transposition of the ventral process from C6 in 44/85, with 30/44 replicating a transverse foramen. A strong statistical dependency existed between C6 grade 4 aCVTs and grades 1–3 aCrVTs and C7 transpositions with replicated transverse foramen. Sidedness was also demonstrated, where a left sided absent C6 associated with transposition on the left ventral surface of C7. This likewise applied to right sidedness and most bilateral cases. These findings might benefit practitioners when radiographing the extent of the ECVM configuration in patients presenting caudal cervical pain.

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Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

Characterization and Association of the Missing Ventral Tubercle(s) from the Sixth Cervical Vertebra and Transpositions on the Ventral Surface of the Seventh Cervical Vertebra in Modern Equus ferus caballus

May-Davis,

Eckelbarger,

Dzingle

et al. 2024

Animals

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Congenital variants of the ventral laminae of the sixth and seventh cervical vertebrae are not associated with clinical signs or other radiological abnormalities of the cervicothoracic region in Warmblood horses

Dyson,

Phillips,

Zheng

et al. 2024

Equine Veterinary Journal

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BackgroundThere is controversy about the clinical relevance of congenital variants of the ventral laminae of the sixth (C6) and seventh (C7) cervical vertebrae and their relationship with other radiological abnormalities.ObjectivesTo document the prevalence of congenital variants of C6 and C7 and that of other radiological abnormalities from C6 to the second thoracic vertebra (T2).Study designCross‐sectional.MethodsThe study included Warmblood horses ≥3 years of age undergoing clinical assessment at two referral institutions: 127 control horses and 96 cases (neurologic, neck pain or stiffness, or neck‐related forelimb lameness). All horses underwent a standardised orthopaedic and neurologic examination. Lateral–lateral and lateral 45°–55° ventral–lateral dorsal (left to right and right to left) radiographic views of C5 to T2 were acquired and assessed blinded to the horse's clinical category using a predetermined grading system.ResultsThe ventral profile of C7 was abnormal in 54 horses (24.2%). Cases were less likely to have congenital variants than control horses, p = 0.0002, relative risk (RR): 0.63 (95% confidence intervals [CIs]: 0.4, 1.0). There was no association between the presence of a congenital variant of C7 and the presence of modelling of the articular processes (APs) of C6–C7, C7–T1 or T1–T2. Cases were more likely to have severe modelling of the APs at C6–C7, p = 0.01, RR: 1.94, CI: 1.1, 3.5 and C7–T1, p = 0.04, RR: 1.97, CI: 1.2, 3.2 compared with control horses.Main limitationsRadiographs were read by one assessor independently at each institution.ConclusionsThere was no association between the presence of congenital variants of C7 and any other radiological findings. Congenital variants occurred less frequently in cases compared with control horses. There was no association between the presence or absence of a congenital variant and the type of case.

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Historic Horse Family Displaying Malformations of the Cervicothoracic Junction and Their Connection to Modern German Warmblood Horses

Zimmermann,

Ros,

Pfarrer

et al. 2023

Animals

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Malformations of the equine cervicothoracic junction affect the C6 and C7 cervical vertebrae, the T1 thoracic vertebra and in variable extent the first and second sternal ribs. To date, the clinical impact of this malformation, its prevalence and mode of inheritance in equine populations are not yet determined. We examined five skeletons for signs of malformation of the cervicothoracic junction, including three skeletons from widely used Thoroughbred stallions affected with the malformation and two skeletons serving as a comparison. The three affected historical horses were the Thoroughbred stallions Der Loewe XX, Birkhahn XX and their common great grandsire Dark Ronald XX. Malformations of C6 and C7 showed a large variation between the three stallions, as Dark Ronald XX, Der Loewe XX and Birkhahn XX were affected uni-laterally at C6 and C7, uni-laterally at C6 and bi-laterally at C6 and C7, respectively, with varying grades. In order to evaluate whether or not these malformations are incidental, we took a random sample of 20 living German Warmblood horses, which are distant descendants of these stallions. This sample consisted of ten controls and ten horses with malformations of C6/C7. Blood proportions of the historical sires in the modern Warmblood horses ranged from 0.10 to 6.25%. The contribution to inbreeding in each individual horse of our selected horse group by those sires was expressed as a percentage of the total inbreeding coefficient and ranged from 0.01 to 17.96%, demonstrating their influence on the modern Warmblood. In the present study, we were able to describe the variability of the malformation of C6/C7 within a horse family including historic and modern horses. Additionally, we detected variations appearing in connection with malformations of the cervicothoracic junction that have not been described in the literature yet. This is the first time that the malformations of C6 and C7 have been described within a familial context, providing hints on inheritance in Thoroughbreds and Warmbloods. It is worthwhile to carry out further studies in a larger setting to gain more comprehensive insights into the inheritance of the malformation and the role of important ancestors.

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Incidence of variations of the transverse processes of the sixth and seventh cervical equine vertebrae

Cited by 3 publications

References 10 publications

Characterization and Association of the Missing Ventral Tubercle(s) from the Sixth Cervical Vertebra and Transpositions on the Ventral Surface of the Seventh Cervical Vertebra in Modern Equus ferus caballus

Characterization and Association of the Missing Ventral Tubercle(s) from the Sixth Cervical Vertebra and Transpositions on the Ventral Surface of the Seventh Cervical Vertebra in Modern Equus ferus caballus

Congenital variants of the ventral laminae of the sixth and seventh cervical vertebrae are not associated with clinical signs or other radiological abnormalities of the cervicothoracic region in Warmblood horses

Historic Horse Family Displaying Malformations of the Cervicothoracic Junction and Their Connection to Modern German Warmblood Horses

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