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Prevalence of dorsal notch and variations in the foramen magnum shape in dogs of different breeds and morphotypes

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Abstract

The study evaluated shape of the foramen magnum (FM) in dog with regard to its constitutional type (small, medium and large breeds) and morphotype (brachycephalic, mesaticephalic and dolichocephalic dogs). We used multi-slice CT scanner to examine occipital area of 138 purebreds dogs. Two studied groups could be distinguished–living animals undergoing standard diagnostic CT procedure (n = 47) and macerated skulls of euthanized dogs (n = 91). Morphometric analysis was focused on presence of dorsal notch within foramen magnum. This anatomical feature was present in 33.3% of examined dogs. It was more often observed in small size dogs (70%) and those of brachycephalic morphotype (94.1%). For the first time dorsal notch was noted in breeds such as French Bulldog, Fox Terrier, Keeshond, Standard Schnauzer, English Bulldog, Cocker Spaniel, Boxer and Rottweiler. We distinguished four different shape of FM: oval, pentagonal, rhomboid and circular. Most common FM shape was oval (41 dogs; 45%) whereas circular type was least observed (5 dogs; 5.5%). The pentagonal shape was noticed in 27 specimens (29.7%) and the rhomboid shape in 18 dogs (19.8%). Authors conclude that dorsal notch is not pathology and should be considered a morphological variation within the normal anatomy. Results presented in this study should be taken into account during interpretation of the CT images of the craniocervical junction.

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Correspondence to Halina Purzyc.

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Kupczyńska, M., Czubaj, N., Barszcz, K. et al. Prevalence of dorsal notch and variations in the foramen magnum shape in dogs of different breeds and morphotypes. Biologia 72, 230–237 (2017). https://doi.org/10.1515/biolog-2017-0018

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