Affiliation:
1. Institute for Animal Breeding and Genetics, University of Veterinary Medicine Hannover (Foundation), 30559 Hannover, Germany
2. Veterinary Clinic PZZ Döhle, 21272 Egestorf, Germany
3. Institute for Anatomy, University of Veterinary Medicine Hannover (Foundation), 30559 Hannover, Germany
Abstract
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.
Funder
Deutsche Forschungsgemeinschaft
University of Veterinary Medicine Hannover, Foundation
Subject
General Veterinary,Animal Science and Zoology
Reference39 articles.
1. Nickel, R., Schummer, A., and Seiferle, E. (2004). Bewegungsapparat, Georg Thieme Verlag.
2. Anatomical variation of the spinous and transverse processes in the caudal cervical vertebrae and the first thoracic vertebra in horses;Santinelli;Equine Vet. J.,2016
3. Gross anatomy of the deep perivertebral musculature in horses;Rombach;Am. J. Vet. Res.,2014
4. The Occurrence of a Congenital Malformation in the Sixth and Seventh Cervical Vertebrae Predominantly Observed in Thoroughbred Horses;J. Equine Vet. Sci.,2014
5. Ex Vivo Computed Tomographic Evaluation of Morphology Variations in Equine Cervical Vertebrae;Veraa;Vet. Radiol. Ultrasound,2016