Radiographic findings and anatomical variations of the caudal cervical area in horses with neck pain and ataxia: case–control study on 116 horses

Abstract

BackgroundAbnormalities of the ventral lamina of the sixth cervical vertebra (AVL-C6) are thought to exert abnormal stress on the articular process joints (APJs) of the cervicothoracic junction. The aim of the study was to investigate the association between AVL-C6 and radiographic findings in the caudal cervical area and between clinical signs of neck pain and ataxia and radiographic findings.MethodsMedical records of horses subjected to cervical radiography were reviewed. Horses were classified into those with neck pain (group C), those with ataxia (group A) and healthy horses (group H). Presence of AVL-C6 and increased size, dysplasia, remodelling, fragmentation and osteochondral fragment at the APJs (C5–T1) were recorded. Univariable logistic regression analysis was performed to identify the associations between explanatory and dependent variables. Variables with P<0.2 were included in the multivariable analysis.ResultsOne hundred and sixteen horses were included (44 in group C, 29 in group A, 66 in group H); 24 of 116 horses had radiographic AVL-C6. Age, AVL-C6 and overall/C6–C7 increase in size remained in the final models.ConclusionsThe presence of AVL-C6 and moderate/severe increase in size of the caudal cervical APJs increase the odds of showing neck pain and, if severe, ataxia.

Morphology of the Ventral Process of the Sixth Cervical Vertebra in Extinct and Extant Equus: Functional Implications

“…In modern E. ferus caballus, reports of the ventral process of C6 being unilaterally or bilaterally absent have been reported in multiple breeds from numerous countries [33][34][35][36][37][38][39][40].…”

“…In domestic mammals, the literature primarily describes the ventral process of C6 relative to educational instruction or veterinary management [6][7][8]12,[20][21][22][23][24][25][26][27][28][29]. Although, extensive literature on pathologies and peer reviewed journals describing anomalous presentations are well documented in some domestic mammals [15,19,24,27,28,[30][31][32][33][34][35][36][37][38][39][40];…”

“…historically, congenital malformations in the fossil record are rare [41]. Therefore, when two domestic species presenting similar congenital malformations in the cervicothoracic junction involving the ventral process of C6 are reported, namely Bos taurus domesticus [30][31][32] and E. ferus caballus [34][35][36][37][38][39][40], further investigations into the fossil record are warranted.…”

“…Hence, preservation in the fossil record is unlikely due to fragmentaion of the associative growth plates relative to the ventral process of C6 [7], plus poor preservation of the specimen, and or predation [41]. However, in modern E. ferus caballus, the condition is not known to be fatal, and the absent CVT on the ventral process of C6 is evident in mature adults, and therefore preservation is more likely [34][35][36][37][38][39][40][41].…”

“…Although clinically the absent CVT on C6 is yet to be defined, several authors have postulated, or documented via case studies symptoms conducive to the congenital malformation [34,38,40]. Therefore, the question is -is this congenital malformation of the absent CVT in C6 a recent event in modern E. ferus caballus or a normal variation in the population?…”